Lower risk of cancer in patients on metformin in comparison with those on sulfonylurea derivatives: results from a large population-based follow-up study

OBJECTIVE

Numerous studies have suggested a decreased risk of cancer in patients with diabetes on metformin. Because different comparison groups were used, the effect magnitude is difficult to estimate. Therefore, the objective of this study was to further analyze whether, and to what extent, use of metformin is associated with a decreased risk of cancer in a cohort of incident users of metformin compared with users of sulfonylurea derivatives.

RESEARCH DESIGN AND METHODS

Data for this study were obtained from dispensing records from community pharmacies individually linked to hospital discharge records from 2.5 million individuals in the Netherlands. The association between the risk of cancer in those using metformin compared with those using sulfonylurea derivatives was analyzed using Cox proportional hazard models with cumulative duration of drug use as a time-varying determinant.

RESULTS

Use of metformin was associated with a lower risk of cancer in general (hazard ratio 0.90 [95% CI 0.88–0.91]) compared with use of sulfonylurea derivatives. When specific cancers were used as end points, similar estimates were found. Dosage-response relations were identified for users of metformin but not for users of sulfonylurea derivatives.

CONCLUSIONS

In our study, cumulative exposure to metformin was associated with a lower risk of specific cancers and cancer in general, compared with cumulative exposure to sulfonylurea derivatives. However, whether this should indeed be seen as a decreased risk of cancer for the use of metformin or as an increased risk of cancer for the use sulfonylurea derivatives remains to be elucidated.As the drug of first choice in type 2 diabetes, metformin is the most widely prescribed oral glucose-lowering drug (OGLD) (1,2). However, the decision to prescribe metformin also depends on patient characteristics: metformin use is contraindicated in those with renal failure, cardiac, or hepatic failure (2).A statistically nonsignificant relationship between use of metformin and the risk of colon cancer was described in 2004 (3). However, 1 year later, metformin was found to be associated with a decreased risk of cancer in general in a case-control study in a diabetic population (4). Numerous studies followed; among which studies confirming the association between use of metformin and a decreased risk of cancer in general (5–8) or in specific cancers (5,6,9–14). However, for breast cancer (5,6) and prostate cancer (5,14), the decreased risk was not consistently demonstrated; for other cancers, no association with use of metformin was found (6,12). Hence, there is heterogeneity among published studies on cancer in patients with diabetes on metformin (15), partly because different comparison groups were used, such as nonmetformin users, users of other OGLDs, or users of insulin. Higher endogenous insulin levels have been linked to an increased risk of certain cancers (16). Moreover, specifically for insulin glargine, the debate whether this specific insulin increases the risk of cancer is ongoing (17–21).Owing to factors such as different drugs used to attain metabolic control, the duration of diabetes, and the presence of other diseases, the assessment of cancer risk in diabetic patients remains difficult. Therefore, the objective of this study was to analyze whether, and to what extent, use of metformin is associated with a decreased risk of cancer in a cohort of incident users of metformin compared with use of sulfonylurea derivatives.     

Association Between Metformin Therapy and Mortality After Breast Cancer: A population-based study

OBJECTIVE

Metformin has been associated with a reduction in breast cancer risk and may improve survival after cancer through direct and indirect tumor-suppressing mechanisms. The purpose of this study was to evaluate the effect of metformin therapy on survival in women with breast cancer using methods that accounted for the duration of treatment with glucose-lowering therapies.

RESEARCH DESIGN AND METHODS

This population-based study, using Ontario health care databases, recruited women aged 66 years or older diagnosed with diabetes and breast cancer between 1 April 1997 and 31 March 2008. Using Cox regression analyses, we explored the association between cumulative duration of past metformin use and all-cause and breast cancer–specific mortality. We modeled cumulative duration of past metformin use as a time-varying exposure.

RESULTS

Of 2,361 breast cancer patients identified, mean (± SD) age at cancer diagnosis was 77.4 ± 6.3 years, and mean follow-up was 4.5 ± 3.0 years. There were 1,101 deaths(46.6%), among which 386 (16.3%) were breast cancer–specific deaths. No significant association was found between cumulative duration of past metformin use and all-cause mortality (adjusted hazard ratio 0.97 [95% CI 0.92–1.02]) or breast cancer–specific mortality (0.91 [0.81–1.03]) per additional year of cumulative use.

CONCLUSIONS

Our findings failed to show an association between improved survival and increased cumulative metformin duration in older breast cancer patients who had recent-onset diabetes. Further research is needed to clarify this association, accounting for effects of cancer stage and BMI in younger populations or those with differing stages of diabetes as well as in nondiabetic populations.Pre-existing diabetes may increase the risk of death by as much as 40% in cancer patients (1). Up to 16% of patients with breast cancer have pre-existing diabetes and are thus at risk for worse outcomes (2,3). Metformin, an insulin sensitizer, is the most commonly prescribed diabetes treatment and is currently recommended as first-line therapy for patients with type 2 diabetes (4,5). If glycemic targets are not met with metformin alone, other glucose-lowering medications are added to or substituted for metformin. Recent evidence suggests that metformin may have antitumor effects (6). Several studies have evaluated the effect of metformin on cancer incidence, and meta-analyses suggest that metformin is associated with a 20–30% reduction in new cancers (6–8). However, of greater interest is the potential therapeutic role of metformin in patients with pre-existing cancer.There is mounting evidence that metformin may affect the prognosis of breast cancer. Metformin use has been associated with higher rates of pathologic complete response after chemotherapy in breast cancer patients with diabetes (9), and clinical trials have shown a reduction in tumor proliferation markers in nondiabetic breast cancer patients treated with metformin (10–12). However, observational studies evaluating the effect of metformin on survival after breast cancer have been inconsistent. One study of women with HER2+ breast cancer found metformin exposure was associated with a 48% reduction in overall mortality compared with other glucose-lowering medications (13). However, another study of women with triple-negative receptor breast cancer did not show a significant association between metformin and cancer mortality (hazard ratio [HR] 1.63 [95% CI 0.87–3.06]) (13,14). Interpretation of these previous studies is hampered by small sample sizes, heterogeneity of disease subtypes, inclusion of diabetic populations with varying disease severity and duration, and inconsistent definitions of metformin exposure. The objective of this study was to evaluate the relationship between cumulative metformin use and mortality in patients with breast cancer and recently diagnosed diabetes.     

Pleiotropic Action of Short-Term Metformin and Fenofibrate Treatment, Combined With Lifestyle Intervention, in Type 2 Diabetic Patients With Mixed Dyslipidemia

OBJECTIVE

To compare the effect of short-term metformin and fenofibrate treatment, administered alone or in sequence, on glucose and lipid metabolism, cardiovascular risk factors, and monocyte cytokine release in type 2 diabetic patients with mixed dyslipidemia.

RESEARCH DESIGN AND METHODS

We studied 128 type 2 diabetic patients with mixed dyslipidemia complying throughout the study with lifestyle intervention who were randomized twice, initially to either metformin or placebo, and then to micronized fenofibrate or placebo.

RESULTS

Fenofibrate alleviated diabetic dyslipidemia–induced changes in plasma high-sensitivity C-reactive protein, fibrinogen, and plasminogen activator inhibitor (PAI)-1 and in monocyte cytokine release, whereas metformin or lifestyle intervention improved mainly glucose and lipid metabolism. The strongest pleiotropic effect was observed when fenofibrate was added to metformin.

CONCLUSIONS

Fenofibrate, particularly administered together with metformin, is superior to metformin and lifestyle intervention in exhibiting beneficial effects on systemic inflammation, hemostasis, and monocyte secretory function in type 2 diabetic patients with mixed dyslipidemia.Peroxisome proliferator–activated receptor (PPAR)-α activators (fibrates) administered to patients with dyslipidemia (1–4) or early glucose metabolism abnormalities (5) produce many non–lipid-related effects, including anti-inflammatory, antioxidant, and antithrombotic actions and improvement in endothelial function. Apart from normalizing glucose metabolism, metformin, the only oral antidiabetic medication shown to decrease cardiovascular events independent of glycemic control (6), improved dyslipidemia, hemostasis, and systemic inflammation (7). To the best of our knowledge, no previous clinical study has ever compared clinical benefits of metformin and fibrates when it comes to their pleiotropic effects and assessed whether metformin-fibrate combination is superior to treatment with only one of these drugs.     

Reduced risk of colorectal cancer with metformin therapy in patients with type 2 diabetes: a meta-analysis

OBJECTIVE

Both in vitro and in vivo studies indicate that metformin inhibits cancer cell growth and reduces cancer risk. Recent epidemiological studies suggest that metformin therapy may reduce the risks of cancer and overall cancer mortality among patients with type 2 diabetes. However, data on its effect on colorectal cancer are limited and inconsistent. We therefore pooled data currently available to examine the association between metformin therapy and colorectal cancer among patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

The PubMed and SciVerse Scopus databases were searched to identify studies that examined the effect of metformin therapy on colorectal cancer among patients with type 2 diabetes. Summary effect estimates were derived using a random-effects meta-analysis model.

RESULTS

The analysis included five studies comprising 108,161 patients with type 2 diabetes. Metformin treatment was associated with a significantly lower risk of colorectal neoplasm (relative risk [RR] 0.63 [95% CI 0.50–0.79]; P < 0.001). After exclusion of one study that investigated colorectal adenoma, the remaining four studies comprised 107,961 diabetic patients and 589 incident colorectal cancer cases during follow-up. Metformin treatment was associated with a significantly lower risk of colorectal cancer (0.63 [0.47–0.84]; P = 0.002). There was no evidence for the presence of significant heterogeneity between the five studies (Q = 4.86, P = 0.30; I² = 18%).

CONCLUSIONS

From observational studies, metformin therapy appears to be associated with a significantly lower risk of colorectal cancer in patients with type 2 diabetes. Further investigation is warranted.Colorectal cancer is one of the most frequent malignant tumors and a leading cause of cancer-related death worldwide (1). The incidence of colorectal cancer continues to increase in economically transitioning countries such as Asia, Eastern Europe, and selected countries in South America (2,3), whereas a declining trend has been noted in several developed countries in recent years (1).Type 2 diabetes is also a common disease, and it is well established that type 2 diabetes is associated with a higher risk of colorectal cancer (4–8). Metformin is a relative of isoamylene guanidine and has been recommended as the initial glucose-lowering therapy for diabetes. Emerging evidence from both in vitro and in vivo studies indicates that metformin may inhibit cancer cell growth and reduce cancer risks. Previous research suggests that metformin may be involved in the tumor suppressor pathway by indirectly activating AMP-activated protein kinase (9)—a key sensor of cellular ATP and AMP balance—and plays a role on activating tumor suppressor genes, e.g., LKB1. Subsequent in vitro studies have shown that metformin inhibits cancer cell proliferation (10,11) and selectively kills cancer stem cells (12). Animal experiments concur with these findings. Rodent models have shown that metformin suppresses colonic epithelial proliferation and colorectal aberrant crypt foci formation (13,14). Similarly, animal models of colon cancer have shown that metformin inhibits colon carcinoma growth (11,15). Given these encouraging findings, interest has arisen that metformin could potentially serve as a new antineoplasm drug to prevent colorectal cancer.Results from preliminary studies conducted in humans are encouraging. In a short-term randomized clinical trial among nondiabetic patients with rectal aberrant crypt foci, a significant decrease in the mean number of aberrant crypt foci was observed after metformin treatment for 1 month as compared with no significant changes in the control group (16). Findings from several epidemiological studies also support an antineoplastic role of metformin on cancer risks (17,18). If metformin therapy ultimately proves effective on reducing the risk of colorectal cancer, it would likely be recommended for the overwhelming majority of diabetes patients for both blood glucose control and cancer prevention. Nonetheless, despite accumulating evidence from population studies that indicate a lower risk of cancer at large with metformin therapy (17,19,20), data on its effect on colorectal cancer are limited and inconsistent. Accordingly, we performed a meta-analysis to pool studies currently available to examine the effect of metformin treatment on colorectal cancer risk among patients with type 2 diabetes.     

Long-Term Safety and Efficacy of Empagliflozin,Sitagliptin, and Metformin: An active-controlled,parallel-group,randomized, 78-week open-label extension study in patients with type 2 diabetes

OBJECTIVE

To investigate the long-term safety and efficacy of empagliflozin, a sodium glucose cotransporter 2 inhibitor; sitagliptin; and metformin in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

In this randomized, open-label, 78-week extension study of two 12-week, blinded, dose-finding studies of empagliflozin (monotherapy and add-on to metformin) with open-label comparators, 272 patients received 10 mg empagliflozin (166 as add-on to metformin), 275 received 25 mg empagliflozin (166 as add-on to metformin), 56 patients received metformin, and 56 patients received sitagliptin as add-on to metformin.

RESULTS

Changes from baseline in HbA_1c at week 90 were −0.34 to −0.63% (−3.7 to −6.9 mmol/mol) with empagliflozin, −0.56% (−6.1 mmol/mol) with metformin, and −0.40% (−4.4 mmol/mol) with sitagliptin. Changes from baseline in weight at week 90 were −2.2 to −4.0 kg with empagliflozin, −1.3 kg with metformin, and −0.4 kg with sitagliptin. Adverse events (AEs) were reported in 63.2–74.1% of patients on empagliflozin and 69.6% on metformin or sitagliptin; most AEs were mild or moderate in intensity. Hypoglycemic events were rare in all treatment groups, and none required assistance. AEs consistent with genital infections were reported in 3.0–5.5% of patients on empagliflozin, 1.8% on metformin, and none on sitagliptin. AEs consistent with urinary tract infections were reported in 3.8–12.7% of patients on empagliflozin, 3.6% on metformin, and 12.5% on sitagliptin.

CONCLUSIONS

Long-term empagliflozin treatment provided sustained glycemic and weight control and was well tolerated with a low risk of hypoglycemia in patients with type 2 diabetes.Type 2 diabetes is characterized by insulin resistance and progressive deterioration of β-cell function (1). Metformin is the recommended first-line antidiabetes agent for patients with type 2 diabetes (2). However, in order to achieve and maintain glycemic control as the disease progresses, patients often require therapies in addition to metformin (2,3).Despite the availability of a number of antihyperglycemic agents, the side effects associated with existing treatments and their gradual loss of efficacy over time (2,3) mean that many patients with type 2 diabetes do not reach therapeutic goals (3,4). In addition, treatment is often complicated by common comorbidities of type 2 diabetes such as obesity and hypertension, which are not addressed by existing oral antidiabetes agents (5–7).Inhibition of sodium glucose cotransporter 2 (SGLT2), located in the proximal tubule of the kidney, represents an approach for the treatment of type 2 diabetes that is independent of β-cell function and insulin resistance (8,9). SGLT2 mediates most of renal glucose reabsorption, and inhibition of this transporter leads to reduced reabsorption of filtered glucose and increased urinary glucose excretion (8,10), resulting in reduced plasma glucose levels in patients with type 2 diabetes (8–10). In addition, this mechanism leads to weight loss owing to the loss of calories via urinary glucose excretion (8,11).Empagliflozin is a potent and selective inhibitor of SGLT2 (12), which in patients with type 2 diabetes causes urinary glucose excretion of up to 90 g/day (13). In two placebo- and active-controlled, dose-finding trials, treatment with empagliflozin for 12 weeks in patients with type 2 diabetes was generally well tolerated and resulted in placebo-corrected reductions in HbA_1c of up to 0.72% (7.9 mmol/mol) and placebo-corrected reductions in weight of up to 1.7 kg (14,15). In these studies, reductions in HbA_1c were comparable to those of the active comparators metformin and sitagliptin (14,15). The objective of this study was to assess the long-term safety and efficacy of empagliflozin, sitagliptin, and metformin in a 78-week, open-label extension study of two dose-finding trials.     

Rosiglitazone Decreases C-Reactive Protein to a Greater Extent Relative to Glyburide and Metformin Over 4 Years Despite Greater Weight Gain: Observations from A Diabetes Outcome Progression Trial (ADOPT)

OBJECTIVE

C-reactive protein (CRP) is closely associated with obesity and cardiovascular disease in both diabetic and nondiabetic populations. In the short term, commonly prescribed antidiabetic agents have different effects on CRP; however, the long-term effects of those agents are unknown.

RESEARCH DESIGN AND METHODS

In A Diabetes Outcome Progression Trial (ADOPT), we examined the long-term effects of rosiglitazone, glyburide, and metformin on CRP and the relationship among CRP, weight, and glycemic variables in 904 subjects over 4 years.

RESULTS

Baseline CRP was significantly correlated with homeostasis model assessment of insulin resistance (HOMA-IR), A1C, BMI, waist circumference, and waist-to-hip ratio. CRP reduction was greater in the rosiglitazone group by −47.6% relative to glyburide and by −30.5% relative to metformin at 48 months. Mean weight gain from baseline (at 48 months) was 5.6 kg with rosiglitazone, 1.8 kg with glyburide, and −2.8 kg with metformin. The change in CRP from baseline to 12 months was correlated positively with change in BMI in glyburide (r = 0.18) and metformin (r = 0.20) groups but not in the rosiglitazone (r = −0.05, NS) group. However, there was no longer a significant correlation between change in CRP and change in HOMA-IR, A1C, or waist-to-hip ratio in any of the three treatment groups.

CONCLUSIONS

Rosiglitazone treatment was associated with durable reductions in CRP independent of changes in insulin sensitivity, A1C, and weight gain. CRP in the glyburide and metformin groups was positively associated with changes in weight, but this was not the case with rosiglitazone.C-reactive protein (CRP) has been traditionally viewed as one of the acute-phase reactants and is a sensitive systemic marker of inflammation and tissue damage. This acute-phase inflammatory protein is predominantly secreted in hepatocytes, its release being regulated by interleukin-6 and other inflammatory cytokines (1). Other studies have shown that extrahepatic sources of CRP production from adipocytes could point to a more systemic generation of CRP in the body after stimulation by inflammatory cytokines and more specifically, by the adipokine, resistin (1).Both population-based and prospective studies have demonstrated a clear association between CRP and an increased risk of cardiovascular disease (CVD) and stroke (2). The magnitude of the CRP prediction for future CVD events is similar to that of other traditional CVD risk factors (cholesterol, hypertension, and smoking status) (2). CRP also may be a mediator of atherosclerosis (1,3–6). However, there is no available evidence from clinical trials that a reduction in CRP directly reduces or prevents further CVD events.The production of CRP by adipocytes may partially explain why CRP levels are elevated in patients with the metabolic syndrome (1), in whom CVD risk is increased. The strong association between CRP and body adiposity has been observed in both diabetic (7) and nondiabetic subjects (8–11) and was only moderately attenuated by adjustment of insulin sensitivity. These results suggest that obesity, insulin resistance, and the metabolic syndrome are interconnected in a proinflammatory state that may be mediated by cytokines and subsequently cause elevated levels of CRP. Elevated CRP concentrations have been shown to predict an increased risk of diabetes (9,12,13). Therefore, CRP may play an active role in the causal relationship among obesity, diabetes, and the high risk of future CVD events. Statins (14) and weight loss (15–17), which can reduce CRP levels and improve other CVD risk factors, also show benefits in reducing CVD events.Glucose-lowering agents have different effects on CRP, weight, insulin sensitivity, and glycemic control in the treatment of type 2 diabetes. The thiazolidinediones (TZDs) rosiglitazone and pioglitazone, insulin-sensitizing oral antidiabetic agents, have been shown to be effective in reducing CRP in several short-term (≤6 months) studies (18–21). However, it is not clear whether the weight gain associated with TZDs could attenuate the effect on CRP reduction over larger periods of time. In short-term studies, metformin moderately decreases CRP (16,18), increases insulin sensitivity, and produces weight loss (16). The longer-term relationships among the three commonly used oral antidiabetic agents (TZDs, sulfonylureas, and metformin) with CRP, insulin sensitivity, weight, and glycemic control have not been investigated previously.A Diabetes Outcome Progression Trial (ADOPT) provided the opportunity to evaluate the effects of members of these three classes of oral agents in a randomized, double-blind, controlled trial involving >4,000 patients, treated for a median time of 4 years (22,23). This study compared the efficacy and safety of rosiglitazone, glyburide, and metformin in drug-naive patients with newly diagnosed (≤3 years) type 2 diabetes. We have previously reported the association of CRP, obesity, and insulin resistance in the baseline examination of the ADOPT study (7). We discuss here a subgroup analysis of ADOPT, in which we examined prospectively the long-term effects of rosiglitazone, glyburide, and metformin on CRP reduction and the relationship among CRP, insulin sensitivity, weight, and glycemic variables.     

Maternal and Neonatal Circulating Markers of Metabolic and Cardiovascular Risk in the Metformin in Gestational Diabetes (MiG) Trial: Responses to maternal metformin versus insulin treatment

OBJECTIVE

This study was designed to compare glucose, lipids, and C-reactive protein (CRP) in women with gestational diabetes mellitus treated with metformin or insulin and in cord plasma of their offspring and to examine how these markers relate to infant size at birth.

RESEARCH DESIGN AND METHODS

Women with gestational diabetes mellitus were randomly assigned to metformin or insulin in the Metformin in Gestational Diabetes trial. Fasting maternal plasma glucose, lipids, and CRP were measured at randomization, 36 weeks’ gestation, and 6–8 weeks postpartum as well as in cord plasma. Women with available cord blood samples (metformin n = 236, insulin n = 242) were included.

RESULTS

Maternal plasma triglycerides increased more from randomization to 36 weeks’ gestation in women treated with metformin (21.93%) versus insulin (9.69%, P < 0.001). Maternal and cord plasma lipids, CRP, and neonatal anthropometry did not differ between treatments. In logistic regression analyses adjusted for confounders, the strongest associations with birth weight >90th centile were maternal triglycerides and measures of glucose control at 36 weeks.

CONCLUSIONS

There were few differences in circulating maternal and neonatal markers of metabolic status and no differences in measures of anthropometry between the offspring of women treated with metformin and the offspring of women treated with insulin. There may be subtle effects of metformin on maternal lipid function, but the findings suggest that treating gestational diabetes mellitus with metformin does not adversely affect lipids or CRP in cord plasma or neonatal anthropometric measures.Gestational diabetes mellitus is carbohydrate intolerance first diagnosed during pregnancy (1) and affects up to 18% of pregnancies. The prevalence varies depending on maternal demographics and diagnostic criteria (2). The prevalence of gestational diabetes mellitus is increasing, which is likely driven by the rising population prevalence of overweight and obesity and increasing maternal age at pregnancy (3). Gestational diabetes mellitus increases maternal and infant morbidity and mortality during pregnancy (4). Women with a history of gestational diabetes mellitus are at risk for metabolic syndrome, type 2 diabetes (5), and cardiovascular disease in later life (6). Children born to women with gestational diabetes mellitus have higher rates of type 2 diabetes and obesity (7).Treating gestational diabetes mellitus improves pregnancy outcomes for both mother and infant (8). Current therapies include modification of diet, increased physical activity, and drug therapy with insulin and oral hypoglycemic agents, including metformin. In addition to improving insulin sensitivity and hyperglycemia, metformin therapy in the setting of type 2 diabetes reduces triglycerides (9), total cholesterol, LDL cholesterol (10), and VLDL cholesterol; increases HDL cholesterol (9); and reduces markers of inflammation and thrombosis (11). Metformin therapy in gestational diabetes mellitus achieves maternal glucose control and pregnancy outcomes similar to insulin therapy (12,13).In contrast to insulin, metformin crosses the placenta (14) and, therefore, could directly influence fetal metabolism. Our recent follow-up studies in 2-year-old offspring of women enrolled in the Metformin in Gestational Diabetes (MiG) trial showed increased subcutaneous fat measurements with no increase in abdominal adiposity or total fat (15). Further assessments are required to determine whether metformin actually reduces visceral/ectopic fat. Therefore, we hypothesized that metformin would be more effective than insulin in improving markers of insulin sensitivity and cardiovascular risk during pregnancy and postpartum in women with gestational diabetes mellitus and in their newborns.     

Determinants of Maternal Triglycerides in Women With Gestational Diabetes Mellitus in the Metformin in Gestational Diabetes (MiG) Study

OBJECTIVE

Factors associated with increasing maternal triglyceride concentrations in late pregnancy include gestational age, obesity, preeclampsia, and altered glucose metabolism. In a subgroup of women in the Metformin in Gestational Diabetes (MiG) trial, maternal plasma triglycerides increased more between enrollment (30 weeks) and 36 weeks in those treated with metformin compared with insulin. The aim of this study was to explain this finding by examining factors potentially related to triglycerides in these women.

RESEARCH DESIGN AND METHODS

Of the 733 women randomized to metformin or insulin in the MiG trial, 432 (219 metformin and 213 insulin) had fasting plasma triglycerides measured at enrollment and at 36 weeks. Factors associated with maternal triglycerides were assessed using general linear modeling.

RESULTS

Mean plasma triglyceride concentrations were 2.43 (95% CI 2.35–2.51) mmol/L at enrollment. Triglycerides were higher at 36 weeks in women randomized to metformin (2.94 [2.80–3.08] mmol/L; +23.13% [18.72–27.53%]) than insulin (2.65 [2.54–2.77] mmol/L, P = 0.002; +14.36% [10.91–17.82%], P = 0.002). At 36 weeks, triglycerides were associated with HbA_1c (P = 0.03), ethnicity (P = 0.001), and treatment allocation (P = 0.005). In insulin-treated women, 36-week triglycerides were associated with 36-week HbA_1c (P = 0.02), and in metformin-treated women, they were related to ethnicity.

CONCLUSIONS

At 36 weeks, maternal triglycerides were related to glucose control in women treated with insulin and ethnicity in women treated with metformin. Whether there are ethnicity-related dietary changes or differences in metformin response that alter the relationship between glucose control and triglycerides requires further study.Maternal metabolism in late pregnancy is catabolic, with increasing insulin resistance, decreased adipose tissue lipoprotein lipase (LPL) activity, and increased lipolysis (1). These processes combine to ensure the availability of maternal fuels such as glucose, fatty acids, and ketone bodies for fetal use (1). It is recognized that gestational age, maternal obesity (2), and preeclampsia (3) are associated with increases in lipids during pregnancy. Gestational diabetes mellitus (GDM) is also associated with abnormalities in maternal lipid metabolism (4–6), which may contribute to the elevated fat mass seen at birth in infants of women with GDM (7–10).Maternal glucose control and the pharmacological therapies used for treatment of GDM have the potential to influence these changes in maternal lipids (11). Insulin suppresses adipose tissue lipolysis and might be expected to reduce circulating triglycerides (12). Metformin reduces insulin resistance, but it has also been suggested to influence lipid metabolism (13), independent of glycemic control. In type 2 diabetes, metformin treatment is associated with a reduction in plasma triglyceride, total cholesterol, LDL cholesterol (13), and VLDL cholesterol concentrations (14). Metformin treatment in type 2 diabetes is also associated with increases in LPL mass level and LDL cholesterol particle size (15) and with a reduction in the release of free fatty acids from adipose tissue (16).We have recently examined maternal lipids in the Metformin in Gestational Diabetes (MiG) trial and found that maternal fasting plasma triglycerides and measures of glucose control at 36 weeks were the strongest predictors of customized birth weight >90th percentile (17). Interestingly, triglycerides increased more from randomization to 36 weeks'' gestation in women allocated to metformin than in those allocated to treatment with insulin, but there was no difference in customized birth weights or other neonatal anthropometry measures between the groups; there were also no differences in cord blood triglycerides (17). The aim of this study was to examine the known and putative determinants of maternal triglyceride concentrations and determine whether the difference seen in maternal plasma triglycerides at 36 weeks was due to treatment or other factors that may have differed between treatment groups.     

New Users of Metformin Are at Low Risk of Incident Cancer: A cohort study among people with type 2 diabetes

OBJECTIVE

The antidiabetic properties of metformin are mediated through its ability to activate the AMP-activated protein kinase (AMPK). Activation of AMPK can suppress tumor formation and inhibit cell growth in addition to lowering blood glucose levels. We tested the hypothesis that metformin reduces the risk of cancer in people with type 2 diabetes.

RESEARCH DESIGN AND METHODS

In an observational cohort study using record-linkage databases and based in Tayside, Scotland, U.K., we identified people with type 2 diabetes who were new users of metformin in 1994–2003. We also identified a set of diabetic comparators, individually matched to the metformin users by year of diabetes diagnosis, who had never used metformin. In a survival analysis we calculated hazard ratios for diagnosis of cancer, adjusted for baseline characteristics of the two groups using Cox regression.

RESULTS

Cancer was diagnosed among 7.3% of 4,085 metformin users compared with 11.6% of 4,085 comparators, with median times to cancer of 3.5 and 2.6 years, respectively (P < 0.001). The unadjusted hazard ratio (95% CI) for cancer was 0.46 (0.40–0.53). After adjusting for sex, age, BMI, A1C, deprivation, smoking, and other drug use, there was still a significantly reduced risk of cancer associated with metformin: 0.63 (0.53–0.75).

CONCLUSIONS

These results suggest that metformin use may be associated with a reduced risk of cancer. A randomized trial is needed to assess whether metformin is protective in a population at high risk for cancer.Recent research suggests that the antidiabetic drug metformin, which exerts its effects by activating the AMP-activated protein kinase (AMPK), may have potential for the treatment of cancer in humans (1). The hypothesis that metformin may have anticancer effects is supported by laboratory studies showing that metformin is associated with reduced incidence of pancreatic cancer in hamsters (2) and delays onset of mammary (3) and other tumors (4) in tumor-prone mice. Metformin also inhibits growth of human breast cancer cells (5). Although the potential for prevention of cancer in humans using metformin has not been explored, we previously reported the results of a pilot case-control study that identified a reduced risk of cancer among patients with type 2 diabetes who had used metformin (6). However, the outcome was limited to hospital admissions for cancer, and the date of diagnosis was assumed to be date of first hospital admission.Other diabetic drugs may also have cancer-related effects. An independent epidemiological study found that users of sulfonylureas were at higher risk of cancer-related mortality than metformin users (7). Sulfonylureas (and insulin) increase circulating insulin levels, and hyperinsulinemia may promote carcinogenesis (8). Treatments such as metformin and glitazones reduce insulin resistance, with insulin resistance possibly associated with increased risk of cancer (9). The objective of this study was to test the hypothesis that metformin use is associated with a reduced risk of cancer in people with type 2 diabetes using a national cancer registry to ensure valid diagnoses of cancer with precise dates of diagnosis. We also adjusted results for the effects of exposure to other diabetic drugs.     

Statin use as a moderator of metformin effect on risk for prostate cancer among type 2 diabetic patients

OBJECTIVE

Metformin and statins have shown promise for cancer prevention. This study assessed whether the effect of metformin on prostate cancer (PCa) incidence varied by statin use among type 2 diabetic patients.

RESEARCH DESIGN AND METHODS

The study cohort consisted of 5,042 type 2 diabetic male patients seen in the Veteran Administration Health Care System who were without prior cancer and were prescribed with metformin or sulfonylurea as the exclusive hypoglycemic medication between fiscal years 1999 and 2005. Cox proportional hazards analyses were conducted to assess the differential hazard ratio (HR) of PCa due to metformin by statin use versus sulfonylurea use, where propensity scores of metformin and statin use were adjusted to account for imbalances in baseline covariates across medication groups.

RESULTS

Mean follow-up was ∼5 years, and 7.5% had a PCa diagnosis. Statin use modified the effect of metformin on PCa incidence (P < 0.0001). Metformin was associated with a significantly reduced PCa incidence among patients on statins (HR 0.69 [95% CI 0.50–0.92]; 17 cases/533 metformin users vs. 135 cases/2,404 sulfonylureas users) and an increased PCa incidence among patients not on statins (HR 2.15 [1.83–2.52]; 22 cases/175 metformin users vs. 186 cases/1,930 sulfonylureas users). The HR of PCa incidence for those taking metformin and statins versus those taking neither medication was 0.32 (0.25–0.42).

CONCLUSIONS

Among men with type 2 diabetes, PCa incidence among metformin users varied by their statin use. The potential beneficial influence on PCa by combination use of metformin and statin may be due to synergistic effects.Prostate cancer (PCa) is the most common cancer detected in men in the U.S., accounting for ∼28% of the new cancer burden. Risk for PCa increases significantly with age, and the lifetime risk for a U.S. man is 1 in 6 (1). Although a large proportion of cases will not progress to a life-threatening state, a diagnosis of PCa can have significant daunting effects on the patient and his family, with concomitant lifestyle changes, particularly due to the high risk of voiding and sexual dysfunction resulting from currently available curative treatment options. Therefore, preventive strategies would have substantial benefit. Although risk for PCa has been shown to be lower for men with diabetes (2), preventing PCa is particularly important in men with type 2 diabetes because this population appears to be at higher risk for high-grade PCa compared with men without diabetes (3,4). Metformin and statins, two drug classes with sound safety profiles that are well tolerated, have shown promise for cancer prevention trials, although their efficacy in the prevention or treatment of PCa still remains to be seen (5–11).Metformin is a biguanide drug widely prescribed as a first-line oral antihyperglycemic agent for individuals with type 2 diabetes (12). Its glucose-lowering effects may require activation of AMP-activated protein kinase (AMPK) to inhibit hepatic gluconeogenesis (13), increase peripheral uptake of glucose, and delay gastrointestinal glucose absorption (14). In addition, preclinical and clinical data have suggested antineoplastic effects of metformin, and several potential mechanisms include a reduction of hyperinsulinemia, growth inhibition through activation of the AMPK pathway and downstream inhibition of the mammalian target of rapamycin (mTOR) pathway, blockade of cell cycle progression, and alteration of anti-inflammatory properties (5,15–17).Although the beneficial metabolic effects of metformin make it a good treatment candidate for preventing ensuing metabolic syndrome after androgen-deprivation therapy for PCa (18), there is currently mixed enthusiasm for use of metformin therapy in the prevention of PCa. Observational human studies have examined the effect of metformin on risk or recurrence of PCa. Studies conducted in the general population reported decreased risk for PCa among metformin users (19,20). Given that diabetes has been inversely correlated with PCa risk (2), these early reports may have been subject to this bias. In fact, two studies conducted exclusively among diabetic subjects did not observe a significant reduction in PCa risk by metformin use (21,22); rather, a possible dose-dependent increase in risk was reported (21).Because these results are unexpected and contrast not only with the preclinical data but also with clinical data for other cancers, such as breast cancer, it is important to examine this question in other cohorts using more rigorous approaches to adjust for heterogeneity and potential confounding. For example, because of the high prevalence of dyslipidemia among individuals with type 2 diabetes, a large number will also be treated with a lipid-lowering medication such as a statin drug (23). The combination treatment with metformin and statin has not been explored. Prior studies, such as in Azoulay et al. (21), have adjusted for statin use by including an indicator variable to capture any previous use or no use in their model because statin use has itself been associated with PCa risk. No study has formally examined the interactive and potentially synergistic effects of the combination treatment with both drugs.Supportive evidence for use of statins as a PCa prevention therapy is growing, and two clinical trials are currently being initiated in the U.S. to examine effects of statin use in PCa patients (24). As 3-hydroxy-3-methylglutaryl-CoA reductase inhibitors, statins may affect PCa tumorigenesis by blocking the mevalonate pathway and thus reducing cholesterol and/or through multiple pleiotropic effects, as reviewed in Papadopoulos et al. (25). Clinical data have shown cholesterol levels are strongly correlated with PCa risk, so reduction of cholesterol levels is likely a key factor in the anticancer effects of statins (26,27)We conducted a 7-year cohort study to compare the PCa incidence rate associated with metformin monotherapy versus sulfonylurea monotherapy among male patients with type 2 diabetes in the Veteran Health Administration Health Care System (VAHCS). Further, we assessed whether the metformin effect on the PCa incidence rate could be modified by statin use to better examine the heterogeneity of metformin effect.     

A Single Nucleotide Polymorphism in STK11 Influences Insulin Sensitivity and Metformin Efficacy in Hyperinsulinemic Girls With Androgen Excess

OBJECTIVE

Serine-threonine kinase STK11 catalyzes the AMP-activated protein kinase complex. We tested the hypothesis that a gene variant in STK11 contributes to variation in insulin sensitivity and metformin efficacy.

RESEARCH DESIGN AND METHODS

We studied the effects of a single nucleotide polymorphism (SNP) (rs8111699) in STK11 on endocrine-metabolic and body composition indexes before and after 1 year of metformin in 85 hyperinsulinemic girls with androgen excess, representing a continuum from prepuberal girls with a combined history of low birth weight and precocious pubarche over to postmenarchial girls with hyperinsulinemic ovarian hyperandrogenism. Metformin was dosed at 425 mg/day in younger girls and 850 mg/day in older girls. STK11 rs8111699 was genotyped. Endocrine-metabolic features were assessed in the fasting state; body composition was estimated by absorptiometry.

RESULTS

Genotype effects were similar in younger and older girls. At baseline, the mutated G allele in STK11 rs8111699 was associated with higher insulin and IGF-I levels (both P < 0.005). The response to metformin differed by STK11 genotype: GG homozygotes (n = 24) had robust metabolic improvements, GC heterozygotes (n = 38) had intermediate responses, and CC homozygotes (n = 23) had almost no response. Such differences were found for 1-year changes in body composition, circulating insulin, IGF-I, free androgen index, and lipids (all P < 0.005).

CONCLUSIONS

In hyperinsulinemic girls with androgen excess, the STK11 rs8111699 SNP influences insulin sensitivity and metformin efficacy, so that the girls with the least favorable endocrine-metabolic profile improve most with metformin therapy.Genetic variation in enzymes and transporters mediating the actions and metabolism of medications contribute to interindividual variation in therapeutic response, on the efficacy as well as on the safety side (1).Polycystic ovary syndrome (PCOS) is a common endocrinopathy that affects ∼5–10% of young women; PCOS is characterized by androgen excess plus either anovulation or polycystic ovaries (2,3). A majority of patients with PCOS are insulin resistant, and, accordingly, metformin is often prescribed for this condition, also in adolescents (4,5). In selected girls at high risk for developing hyperinsulinemic ovarian androgen excess, metformin is even under exploration as a potentially preventive treatment; among these high-risk girls are those with a combined history of low birth weight (LBW) and precocious pubarche (6–9).The actions of metformin seem to be largely exerted through activation of AMP-activated protein kinase (AMPK), a conserved regulator of the cellular response to low energy, in many organs, including liver and skeletal muscle (10,11). The activation of AMPK in the liver is catalyzed by serine-threonine kinase (STK11, formerly known as LKB1), a tumor suppressor gene defective in Peutz-Jeghers syndrome (12); deletion of hepatic STK11 in mice results in a nearly complete loss of AMPK activity, leading to adipogenesis and lipogenic gene expression (13). STK11 serves as a mediator of metformin effects, rather than as a direct target of metformin (14).Recently, the C allele of a single nucleotide polymorphism (SNP) (rs8111699) in STK11 has been associated with a reduced ovulatory response to metformin in women with PCOS (15). In a pilot study, we have tested the hypothesis that the same SNP in STK11 also influences the endocrine-metabolic and body composition changes after metformin therapy in girls with hyperinsulinemic androgen excess.     

Independent and combined effects of exercise training and metformin on insulin sensitivity in individuals with prediabetes

OBJECTIVE

Physical activity or metformin enhances insulin sensitivity and opposes the progression from prediabetes to type 2 diabetes. The combination may be more effective because each treatment stimulates AMP-activated protein kinase activity in skeletal muscle. We evaluated the effects of exercise training plus metformin on insulin sensitivity in men and women with prediabetes, compared with each treatment alone.

RESEARCH DESIGN AND METHODS

For 12 weeks, men and women with prediabetes were assigned to the following groups: placebo (P), 2,000 mg/day metformin (M), exercise training with placebo (EP), or exercise training with metformin (EM) (n = 8 per group). Before and after the intervention, insulin sensitivity was measured by euglycemic hyperinsulinemic (80 mU/m²/min) clamp enriched with [6,6-²H]glucose. Changes due to intervention were compared across groups by repeated-measures ANOVA.

RESULTS

All three interventions increased insulin sensitivity (P < 0.05) relative to the control group. The mean rise was 25–30% higher after EP than after either EM or M, but this difference was not significant.

CONCLUSIONS

Insulin sensitivity was considerably higher after 12 weeks of exercise training and/or metformin in men and women with prediabetes. Subtle differences among condition means suggest that adding metformin blunted the full effect of exercise training.Before developing overt diabetes, most individuals spend years in an intermediate condition called prediabetes. Prediabetes is defined by impaired glucose tolerance (IGT), impaired fasting glucose (IFG), or the combination of IGT plus IFG (1). Approximately 79 million individuals in the U.S. have prediabetes and are at risk to develop type 2 diabetes (2). The progression is not inevitable, however. The U.S. Diabetes Prevention Program (DPP) demonstrated that either lifestyle modification (i.e., low-fat diet and increased physical activity) or the antihyperglycemic medication metformin reduced the transition from prediabetes to type 2 diabetes (3).Habitual exercise and metformin each increase peripheral (mainly skeletal muscle) insulin sensitivity in part by stimulating AMP-activated protein kinase (AMPK) (4–8). Combining exercise plus metformin, compared with either treatment alone, may more effectively activate the key regulatory enzyme AMPK and oppose the transition from prediabetes to type 2 diabetes.The American Diabetes Association strongly recommends exercise as a cornerstone therapy for diabetes prevention and, recently, suggested that some individuals with prediabetes be considered for metformin treatment (9,10). The efficacy of combining lifestyle modification with metformin has been tested only a few times (11–15). Results suggest 2–5 kg more weight loss with the addition of metformin compared with lifestyle modification alone (11,12), but little (11,14) or no further (15,16) improvement to insulin sensitivity. However, the use of self-reports to estimate physical activity and surrogates (via fasting glucose and insulin concentrations or responses to oral carbohydrate) (11,13–15) rather than direct measurement of insulin sensitivity using the glucose clamp limits our understanding of the interaction between exercise and metformin. There is considerable need to better understand the potential for additive effects when physical activity and metformin are used concurrently because the scope of the public health problem is so pressing. Therefore, the purpose of this study was to determine the effect of combining exercise training with metformin (EM) on insulin sensitivity in individuals with prediabetes, compared with either treatment alone.     

Association of Metformin, Elevated Homocysteine, and Methylmalonic Acid Levels and Clinically Worsened Diabetic Peripheral Neuropathy

OBJECTIVE

The severity of peripheral neuropathy in diabetic patients varies for unclear reasons. Long-term use of metformin is associated with malabsorption of vitamin B¹² (cobalamin [Cbl]) and elevated homocysteine (Hcy) and methylmalonic acid (MMA) levels, which may have deleterious effects on peripheral nerves. The intent of this study was to clarify the relationship among metformin exposure, levels of Cbl, Hcy, and MMA, and severity of peripheral neuropathy in diabetic patients. We hypothesized that metformin exposure would be associated with lower Cbl levels, elevated Hcy and MMA levels, and more severe peripheral neuropathy.

RESEARCH DESIGN AND METHODS

This was a prospective case-control study of patients with type 2 diabetes and concurrent symptomatic peripheral neuropathy, comparing those who had received >6 months of metformin therapy (n = 59) with those without metformin exposure (n = 63). Comparisons were made using clinical (Toronto Clinical Scoring System and Neuropathy Impairment Score), laboratory (serum Cbl, fasting Hcy, and fasting MMA), and electrophysiological measures (nerve conduction studies).

RESULTS

Metformin-treated patients had depressed Cbl levels and elevated fasting MMA and Hcy levels. Clinical and electrophysiological measures identified more severe peripheral neuropathy in these patients; the cumulative metformin dose correlated strongly with these clinical and paraclinical group differences.

CONCLUSIONS

Metformin exposure may be an iatrogenic cause for exacerbation of peripheral neuropathy in patients with type 2 diabetes. Interval screening for Cbl deficiency and systemic Cbl therapy should be considered upon initiation of, as well as during, metformin therapy to detect potential secondary causes of worsening peripheral neuropathy.Diabetes is an increasingly prevalent disorder with a range of systemic complications including diabetic peripheral neuropathy (DPN), which occurs in up to 50% of diabetic patients and causes sensory, motor, and/or autonomic dysfunction (1). Several pathogenic mechanisms contribute to DPN severity, including microangiopathy, oxidative stress, polyol flux, mitochondrial dysfunction, insulin deficiency, and advanced glycation end products and ligand activation of their receptor (2–5). The course and severity of DPN are further affected by a wide range of comorbid conditions.Vitamin B₁₂ (cobalamin [Cbl]) deficiency may co-occur with diabetes. Although it is most classically associated with subacute combined degeneration, an exclusive peripheral neuropathy presentation can occur, typically manifesting as axonal neuropathy based on electrophysiology and pathology (6–8). Accumulating evidence suggests that Cbl-associated metabolites methylmalonic acid (MMA) and homocysteine (Hcy) are more sensitive (MMA and Hcy) and specific (MMA) indicators of early symptomatic Cbl deficiency than serum Cbl itself (9,10).Metformin, a biguanide, is perennially reported as a pharmacological cause of Cbl deficiency (11–13). The responsible mechanism has been controversial; proposed contributors have included competitive inhibition or inactivation of Cbl absorption, alterations in intrinsic factor levels, bacterial flora, gastrointestinal motility, or ileal morphological structure, and interaction with the cubulin endocytic receptor (11,14,15). Biguanides have recently been shown to impair calcium-dependent membrane activity in the ileum, including uptake of the Cbl-intrinsic factor complex (16).Metformin is recommended by the American Diabetes Association and the European Association for the Study of Diabetes as initial medical therapy for type 2 diabetes at diagnosis (17). Despite its wide use and its known effects on Cbl, metformin has not been systematically studied as a potential iatrogenic cause of or contributor to DPN. The potentially reversible effect of cobalamin deficiency may increase the clinical burden for a population of patients with DPN whose sensory function, gait, and balance frequently are already compromised.We designed a prospective case-control study to assess the effects of prolonged metformin intake in patients with type 2 diabetes matched for disease duration and disease control. We specifically examined the relationship among metformin use, levels of Cbl and its metabolites, and clinical and electrophysiological markers of peripheral neuropathy severity. We hypothesized first that metformin use would be associated with biochemical evidence of Cbl deficiency (lower serum Cbl levels and elevated MMA and Hcy) and second that metformin use would be associated with more severe peripheral neuropathy. Decreases in Cbl have been shown to depend on the dose and duration of metformin therapy in a previous case-control study (18); this finding led us to further hypothesize that biochemical abnormalities and severity of neuropathy would correlate with cumulative lifetime metformin dose.     

Association Between Circulating Soluble Receptor for Advanced Glycation End Products and Atherosclerosis: Observations from the Dallas Heart Study

OBJECTIVE

To determine the association between circulating soluble receptor for advanced glycation end products (sRAGE) and coronary atherosclerosis.

RESEARCH DESIGN AND METHODS

Using data from the Dallas Heart Study, a probability-based population sample, the association between plasma levels of sRAGE and coronary artery calcium (CAC) was assessed among 2,571 subjects with complete imaging and sRAGE data.

RESULTS

An inverse graded association was observed between sRAGE quartiles and CAC, with CAC prevalence of 28.5% in quartile 1 compared with 15.7% in quartile 4 (P < 0.0001). After multivariable adjustment, the associations between sRAGE levels in the first and second quartiles (versus fourth quartile) and CAC remained statistically significant (adjusted odds ratio 1.71 [95% CI 1.2–2.4] and 1.5 [1.0–2.1], respectively).

CONCLUSIONS

sRAGE is a novel biomarker that is inversely associated with coronary atherosclerosis. The role of sRAGE in the pathobiology of atherosclerosis and its potential prognostic and therapeutic implications warrant further investigation.The transmembrane receptor for advanced glycation end products (RAGE), expressed on a variety of cells including endothelial, smooth muscle, and mononuclear cells, binds advanced glycation end products and other proinflammatory ligands and modulates activity of several prothrombotic and proinflammatory mediators (1,2). Results from animal models provide evidence supporting a role for ligand-RAGE binding in the development and progression of atherosclerosis (3–5).A circulating isoform of RAGE, soluble RAGE (sRAGE), has been identified (6,7) and theorized to competitively inhibit transmembrane RAGE-ligand binding, thereby attenuating atherosclerosis (3–5). This hypothesis has been supported by animal experiments, where administration of sRAGE to mouse models retarded the progression of atherosclerosis (3–5).Few human studies have been performed evaluating the association between circulating sRAGE and human atherosclerosis (8,9). The objective of the present study was to determine the association between sRAGE and atherosclerosis.     

The Efficacy and Safety of Saxagliptin When Added to Metformin Therapy in Patients With Inadequately Controlled Type 2 Diabetes With Metformin Alone

OBJECTIVE

This 24-week trial assessed the efficacy and safety of saxagliptin as add-on therapy in patients with type 2 diabetes with inadequate glycemic control with metformin alone.

RESEARCH DESIGN AND METHODS

This was a randomized, double-blind, placebo-controlled study of saxagliptin (2.5, 5, or 10 mg once daily) or placebo plus a stable dose of metformin (1,500–2,500 mg) in 743 patients (A1C ≥7.0 and ≤10.0%). Efficacy analyses were performed using an ANCOVA model using last observation carried forward methodology on primary (A1C) and secondary (fasting plasma glucose [FPG] and postprandial glucose [PPG] area under the curve [AUC]) end points.

RESULTS

Saxagliptin (2.5, 5, and 10 mg) plus metformin demonstrated statistically significant adjusted mean decreases from baseline to week 24 versus placebo in A1C (−0.59, −0.69, and −0.58 vs. +0.13%; all P < 0.0001), FPG (−14.31, −22.03, and −20.50 vs. +1.24 mg/dl; all P < 0.0001), and PPG AUC (−8,891, −9,586, and −8,137 vs. −3,291 mg · min/dl; all P < 0.0001). More than twice as many patients achieved A1C <7.0% with 2.5, 5, and 10 mg saxagliptin versus placebo (37, 44, and 44 vs. 17%; all P < 0.0001). β-Cell function and postprandial C-peptide, insulin, and glucagon AUCs improved in all saxagliptin treatment groups at week 24. Incidence of hypoglycemic adverse events and weight reductions were similar to those with placebo.

CONCLUSIONS

Saxagliptin once daily added to metformin therapy was generally well tolerated and led to statistically significant improvements in glycemic indexes versus placebo added to metformin in patients with type 2 diabetes inadequately controlled with metformin alone.Saxagliptin is a potent, selective dipeptidyl peptidase-4 (DPP-4) inhibitor, specifically designed for extended inhibition of the DPP-4 enzyme (1,2). DPP-4 rapidly cleaves and inactivates the incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) (1). GLP-1 and GIP regulate blood glucose homeostasis by stimulation of glucose-dependent insulin secretion (3). GLP-1 also delays gastric emptying and inhibits glucagon secretion (3,4). In rodents, GLP-1 has been shown to stimulate β-cell growth and differentiation and inhibit β-cell apoptosis (5). Such an approach is needed because the majority of patients with type 2 diabetes fail to achieve recommended glycemic targets with existing therapies, owing to safety and tolerability issues and loss of efficacy over time (6).Metformin is the most widely prescribed first-line agent for the management of type 2 diabetes and is standard first-line pharmacotherapy, along with diet and exercise (7). Mechanistically, metformin reduces hepatic glucose production and improves insulin sensitivity (8); however, metformin alone is frequently insufficient to maintain glycemic goals in the face of progressive β-cell failure and increasing insulin resistance (9). Consequently, many patients require multiple oral antihyperglycemic agents (9,10). Metformin works through pathways complementary to saxagliptin, and the combination of saxagliptin with metformin may improve glycemic control (11,12). Studies of other DPP-4 inhibitors in combination with metformin over 24 weeks have demonstrated increased efficacy versus placebo (13–15). The safety and efficacy of saxagliptin monotherapy in treatment-naive patients were established previously in a 12-week study across a dose range of 2.5 to 40 mg/day. Significant A1C reductions were demonstrated in all active treatment groups with maximal A1C efficacy observed with 5 mg saxagliptin. A test for log-linear trend across the treatment groups did not demonstrate a statistically significant dose response after 12 weeks of treatment. The overall frequency of adverse events was comparable across all treatment groups and placebo and did not appear to be dose related (16). The current trial (CV181-014) examined the efficacy and safety of saxagliptin in combination with metformin administered for up to 24 weeks in patients with type 2 diabetes inadequately controlled with metformin alone.     

Sex and Racial/Ethnic Differences in Cardiovascular Disease Risk Factor Treatment and Control Among Individuals With Diabetes in the Multi-Ethnic Study of Atherosclerosis (MESA)

OBJECTIVE

To examine sex and racial/ethnic differences in cardiovascular risk factor treatment and control among individuals with diabetes in the Multi-Ethnic Study of Atherosclerosis (MESA).

RESEARCH DESIGN AND METHODS

This study was an observational study examining mean levels of cardiovascular risk factors and proportion of subjects achieving treatment goals.

RESULTS

The sample included 926 individuals with diabetes. Compared with men, women were 9% less likely to achieve LDL cholesterol <130 mg/dl (adjusted prevalence ratio 0.91 [0.83–0.99]) and systolic blood pressure (SBP) <130 mmHg (adjusted prevalence ratio 0.91 [0.85–0.98]). These differences diminished over time. A lower percentage of women used aspirin (23 vs. 33%; P < 0.001). African American and Hispanic women had higher mean levels of SBP and lower prevalence of aspirin use than non-Hispanic white women.

CONCLUSIONS

Women with diabetes had unfavorable cardiovascular risk factor profiles compared with men. African American and Hispanic women had less favorable profiles than non-Hispanic white women.Population-based health survey data suggest that sex and racial/ethnic disparities are present in diabetes process of care measures and cardiovascular risk factor control (1–9). Available data also indicate that sex-specific race/ethnicity differences are present in cardiovascular risk factor control, but these data are limited to Medicare and Veterans'' Hospital patient populations (5,10–13). We therefore performed analyses of participants with diabetes in the Multi-Ethnic Study of Atherosclerosis (MESA) to examine sex and sex-specific racial/ethnic differences in cardiovascular risk factor treatment and control.     

Peri-Conceptional A1C and Risk of Serious Adverse Pregnancy Outcome in 933 Women With Type 1 Diabetes

OBJECTIVE

To study the association between peri-conceptional A1C and serious adverse pregnancy outcome (congenital malformations and perinatal mortality).

RESEARCH DESIGN AND METHODS

Prospective data were collected in 933 singleton pregnancies complicated by type 1 diabetes.

RESULTS

The risk of serious adverse outcome at different A1C levels was compared with the background population. The risk was significantly higher when peri-conceptional A1C exceeded 6.9%, and the risk tended to increase gradually with increasing A1C. Women with A1C exceeding 10.4% had a very high risk of 16%. Congenital malformation rate increased significantly at A1C above 10.4%, whereas perinatal mortality was increased even at A1C below 6.9%.

CONCLUSIONS

These results support recent guidelines of preconceptional A1C levels <7% in women with type 1 diabetes.Recently, guidelines for management of pregnancy in women with pregestational diabetes have recommended pregestational A1C values <7.0% (1,2) and <6.1% (3). Previous studies have reported information of early A1C including 116–691 pregnancies (4–10). We aimed to study whether there is a threshold value for peri-conceptional A1C in women with type 1 diabetes below which the risk of serious adverse pregnancy outcome (congenital malformation and perinatal mortality) is not increased.