Combination therapy with nateglinide and a thiazolidinedione improves glycemic control in type 2 diabetes

OBJECTIVE: To compare the effects of monotherapy using nateglinide and the thiazolidinedione troglitazone with initial combination of the two agents on glycated hemoglobin (HbA(1c)) in patients with type 2 diabetes inadequately controlled by diet alone. RESEARCH DESIGN AND METHODS: This study consisted of a 28-week, double-blind, randomized, multicenter study that included a 4-week, single-blind, placebo, run-in period and a 24-week (shortened to 16 weeks), double-blind, active treatment period. RESULTS: At the 16-week end point, nateglinide 120 mg, troglitazone 600 mg, and the combination of the agents achieved statistically significant decreases in HbA(1c) in comparison with placebo and a baseline HbA(1c) of 8.1-8.4% (P < 0.001). The reductions in HbA(1c) were similar in the nateglinide (0.6%) and troglitazone (0.8%) monotherapy groups. The reduction in HbA(1c) (1.7%) was greatest in the combination group; 79% of patients in the combination group achieved HbA(1c) levels of <7%. The combination group had a higher number of adverse events, primarily due to an increased incidence of mild hypoglycemia in this treatment group. CONCLUSIONS: Nateglinide and troglitazone are equally effective in decreasing HbA(1c) levels. However, these reductions from baseline HbA(1c) values of >8% are not adequate to achieve HbA(1c) levels of <7%. In contrast, the combination of nateglinide and of a thiazolidinedione shows an additive effect that is highly effective in reducing HbA(1c) levels to the target of <7% in 66% of patients, from a baseline HbA(1c) that is just above 8%.     

Improved control of mealtime glucose excursions with coadministration of nateglinide and metformin

OBJECTIVE: Nateglinide, a new short-acting D-phenylalanine derivative for treating type 2 diabetes, reduces mealtime blood glucose excursions by physiologic regulation of insulin secretion. This study evaluated the pharmacokinetic and pharmacodynamic interactions of nateglinide and metformin in subjects with type 2 diabetes. RESEARCH DESIGN AND METHODS: A total of 12 type 2 diabetic subjects with the following baseline characteristics were enrolled: age, 56 +/- 13 years; BMI, 28.7 +/- 4.5 kg/m2; HbA1c, 8.4 +/- 1.3%; and fasting plasma glucose 13 +/- 2.8 mmol/l. All subjects had been previously treated with glyburide and were switched to metformin monotherapy for 3 weeks before study start. Subjects then randomly received, in combination with 500 mg metformin, either 120 mg nateglinide or placebo before meals for 1 day, followed by the alternate treatment 7 days later. After 1 week of washout from both drugs, subjects received 1 day of open-label nateglinide treatment. Plasma concentrations of glucose, insulin, nateglinide, and metformin were assessed frequently during inpatient periods. RESULTS: Postmeal plasma glucose levels were significantly lower in subjects treated with nateglinide plus metformin than in those treated with either drug alone (P < 0.001), especially after lunch and dinner. Coadministration of nateglinide and metformin did not affect the pharmacokinetics of either drug. All treatments were safe and well tolerated. CONCLUSIONS: Combination therapy with nateglinide and metformin was more effective than either treatment alone and did not result in any pharmacokinetic interactions. Coadministration of nateglinide and metformin appears to be an excellent option for treating patients with type 2 diabetes not controlled with monotherapy.     

Once- and twice-daily dosing with rosiglitazone improves glycemic control in patients with type 2 diabetes

OBJECTIVE: To determine the efficacy of rosiglitazone compared with placebo in reducing hyperglycemia. RESEARCH DESIGN AND METHODS: After a 4-week placebo run-in period, 959 patients were randomized to placebo or rosiglitazone (total daily dose 4 or 8 mg) for 26 weeks. The primary measure of efficacy was change in the HbA1c concentration. RESULTS: Rosiglitazone produced dosage-dependent reductions in HbA1c of 0.8, 0.9, 1.1, and 1.5% in the 4 mg o.d., 2 mg b.i.d., 8 mg o.d., and 4 mg b.i.d. groups, respectively, compared with placebo. Clinically significant decreases from baseline in HbA1c were observed in drug-naive patients at all rosiglitazone doses and in patients previously treated with oral monotherapy at rosiglitazone 8 mg o.d. and 4 mg b.i.d. Clinically significant decreases from baseline in HbA1c were also observed with rosiglitazone 4 mg b.i.d. in patients previously treated with combination oral therapy. Approximately 33% of drug-naive patients treated with rosiglitazone achieved HbA1c < or =7% at study end. The proportions of patients with at least one adverse event were comparable among the rosiglitazone and placebo groups. There was no evidence of hepatotoxicity in any treatment group. There were statistically significant increases in weight and serum lipids in all rosiglitazone treatment groups compared with placebo. For LDL and HDL cholesterol, the observed increase appeared to be dose related. CONCLUSIONS: Rosiglitazone at total daily doses of 4 and 8 mg significantly improved glycemic control in patients with type 2 diabetes and was well tolerated.     

Nateglinide alone and in combination with metformin improves glycemic control by reducing mealtime glucose levels in type 2 diabetes

OBJECTIVE: To evaluate the efficacy and tolerability of nateglinide and metformin alone and in combination in type 2 diabetic patients inadequately controlled by diet, focusing on changes in HbA1c, fasting plasma glucose (FPG), and mealtime glucose excursions. RESEARCH DESIGN AND METHODS: In this randomized double-blind study, patients with an HbA1c level between 6.8 and 11.0% during a 4-week placebo run-in received 24 weeks' treatment with 120 mg nateglinide before meals (n = 179), 500 mg metformin three times a day (n = 178), combination therapy (n = 172), or placebo (n = 172). HbA1c and FPG were evaluated regularly, and plasma glucose levels were determined after Sustacal challenge at weeks 0, 12, and 24. Hypoglycemia and other adverse events were recorded. RESULTS: At study end point, HbA1c was reduced from baseline with nateglinide and metformin but was increased with placebo (-0.5, -0.8, and +0.5%, respectively; P < or = 0.0001). Changes in FPG followed the same pattern (-0.7, -1.6, and +0.4 mmol/l; P < or = 0.0001). Combination therapy was additive (HbA1c -1.4% and FPG -2.4 mmol/l; P < or = 0.01 vs. monotherapy). After Sustacal challenge, there was a greater reduction in mealtime glucose with nateglinide monotherapy compared with metformin monotherapy or placebo (adjusted area under the curve [AUC]0-130 min -2.1, -1.1, and -0.6 mmol x h(-1) x l(-1); p < or = 0.0001). An even greater effect was observed with combination therapy (AUC0-130 min -2.5 mmol x h(-1) x l(-1); P < or = 0.0001 vs. metformin and placebo). All regimens were well tolerated. CONCLUSIONS: Nateglinide and metformin monotherapy each improved overall glycemic control but by different mechanisms. Nateglinide decreased mealtime glucose excursions, whereas metformin primarily affected FPG. In combination, nateglinide and metformin had complementary effects, improving HbA1c, FPG, and postprandial hyperglycemia.     

Addition of biphasic insulin aspart 30 to rosiglitazone in type 2 diabetes mellitus that is poorly controlled with glibenclamide monotherapy

BACKGROUND: The incidence of type 2 diabetes mellitus (DM) is rapidly increasing worldwide. Results from large-scale studies show that tight blood glucose (BG) control improves the outcome of patients with type 2 DM. OBJECTIVE: This trial assessed the short-term efficacy and tolerability of adding a thiazolidinedione (rosiglitazone [ROS]) to existing sulfonylurea (SU) therapy (glibenclamide) compared with switching to combination treatment with a premixed insulin (biphasic insulin aspart 30 [BIAsp 30], a rapid-acting insulin analog) and the thiazolidinedione in a select group of patients with type 2 DM whose metabolic control was inadequate with SU monotherapy. METHODS: In this 6-week, multicenter, open-label, parallel-group trial, patients with type 2 DM whose BG level was not adequately controlled with glibenclamide monotherapy (glycosylated hemoglobin [HbA1c] 8%-13%) were randomized either to replace glibenclamide with BIAsp 30 (individually titrated dosages starting with 6-8 U BID) plus rosiglitazone (4 mg once daily) (BIAsp 30 + ROS group) or to add rosiglitazone (4 mg once daily) to their pretrial doses of glibenclamide (GLIB + ROS group). Patients measured their BG levels immediately before each of the 3 main meals, 90 minutes after the start of each meal, and at bedtime, and mean BG levels were calculated at weeks 0 (baseline), 1, 2, 4, 6, and at 2-week follow-up (week 8). The primary end point was change in mean daily BG level during treatment. Secondary end points included preprandial, postprandial, and bedtime BG levels, serum fructosamine level HbA, and fasting BG level, which were measured at each study visit. Tolerability was assessed using hematologic and biochemical parameters, vital signs, and physical examination. RESULTS: Forty-nine patients (32 men, 17 women; mean [SD] age, 59.1 [8.9] years; mean [SD] body mass index, 27.7 [3.7] kg/m2) participated in the study. A significant difference was found between treatments in the change in mean daily BG level from baseline to week 6 (P=0.01). After the 6-week treatment period, change in mean serum fructosamine level was significantly greater for BIAsp 30 + ROS compared with GLIB + ROS (P=0.02). HbA1c decreased in both treatment groups from baseline to study end, but the difference between groups was nonsignificant. The changes in fasting BG from baseline to study end also were nonsignificant between groups. Both combinations were well tolerated. CONCLUSIONS: This short-term study in patients with type 2 DM whose BG level was poorly controlled with glibenclamide monotherapy suggests that switching to a combination of BIAsp 30 + ROS was efficacious and well tolerated and provided an alternative to adding rosiglitazone to existing glibenclamide treatment. The study also suggests that BIAsp 30 may be associated with greater improvements in short-term metabolic control.     

The effects of triple vs. dual and monotherapy with rosiglitazone, glimepiride, and atorvastatin on lipid profile and glycemic control in type 2 diabetes mellitus rats

The present study was undertaken to investigate the effects of triple oral therapy and different combination of rosiglitazone, atorvastatin, and glimepiride on streptozotocin (STZ)-induced diabetic rats. The various biochemical parameters studied included glycosylated hemoglobin (A1c), fasting plasma sugar levels, triglycerides, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and very low-density lipoprotein (VLDL) cholesterol in diabetic and normal rats. The present study demonstrates that atorvastatin could increase the effect of rosiglitazone and glimepiride and lipid-lowering effect of combination of rosiglitazone and glimepiride (GLIM). According to our finding, similar results for rosiglitazone plus atorvastatin were obtained in terms of correcting lipid parameters, whereas the suppressive action of triple oral therapy of rosiglitazone and glimepiride, and atorvastatin on blood glucose, total cholesterol, LDL, VLDL, HDL cholesterol, and triglyceride was more beneficial than that of dual therapy of different combinations and monotherapy.     

Insulin resistance and hyperglycemia in critical illness: role of insulin in glycemic control

Alterations in glucose metabolism, including hyperglycemia associated with insulin resistance, occur in critical illness. Acutely, such alterations result from normal, adaptive activation of endocrine responses, including increased release of catecholamines, cortisol, and glucagon and a reduced glucose uptake capacity. In prolonged critical illness, neuroendocrine changes lead to more extensive metabolic changes that may be associated with development of complications and poor prognosis. Until recently, hyperglycemia was not routinely controlled in intensive care units, except among patients with known diabetes mellitus. Studies have demonstrated that glycemic management in postmyocardial infarction in patients with diabetes is an effective practice. Recent investigation has extended this to demonstrate reduced morbidity and mortality in a surgical critically ill population with and without diabetes mellitus in later phases of critical illness. Although the mechanisms for improved patient outcomes need to be established, this novel approach to management of hyperglycemia in critical illness is a new and important concept for those working in critical care. This article reviews alterations in glucose metabolism which occur in critically ill patients and discusses potential mechanisms and mediators (e.g., hormones, cytokines) that may play a key role in hyperglycemia and insulin resistance during acute and prolonged phases of severe illness. The article addresses the application of insulin protocols and exogenous regulation of glucose concentration in critical illness based on a review of recent intervention studies.     

Effect of repaglinide addition to metformin monotherapy on glycemic control in patients with type 2 diabetes.

OBJECTIVE: To compare the effect of repaglinide in combination with metformin with monotherapy of each drug on glycemic control in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: A total of 83 patients with type 2 diabetes who had inadequate glycemic control (HbA1c > 7.1%) when receiving the antidiabetic agent metformin were enrolled in this multicenter, double-blind trial. Subjects were randomized to continue with their prestudy dose of metformin (n = 27), to continue with their prestudy dose of metformin with the addition of repaglinide (n = 27), or to receive repaglinide alone (n = 29). For patients receiving repaglinide, the optimal dose was determined during a 4- to 8-week titration and continued for a 3-month maintenance period. RESULTS: In subjects receiving combined therapy, HbA1c was reduced by 1.4 +/- 0.2%, from 8.3 to 6.9% (P = 0.0016) and fasting plasma glucose by 2.2 mmol/l (P = 0.0003). No significant changes were observed in subjects treated with either repaglinide or metformin monotherapy in HbA1c (0.4 and 0.3% decrease, respectively) or fasting plasma glucose (0.5 mmol/l increase and 0.3 mmol/l decrease respectively). Subjects receiving repaglinide either alone or in combination with metformin, had an increase in fasting levels of insulin between baseline and the end of the trial of 4.04 +/- 1.56 and 4.23 +/- 1.50 mU/l, respectively (P < 0.02). Gastrointestinal adverse events were common in the metformin group. An increase in body weight occurred in the repaglinide and combined therapy groups (2.4 +/- 0.5 and 3.0 +/- 0.5 kg, respectively; P < 0.05). CONCLUSIONS: Combined metformin and repaglinide therapy resulted in superior glycemic control compared with repaglinide or metformin monotherapy in patients with type 2 diabetes whose glycemia had not been well controlled on metformin alone. Repaglinide monotherapy was as effective as metformin monotherapy.     

Epidemiological studies on the effects of hyperglycemia and improvement of glycemic control on macrovascular events in type 2 diabetes

The relation of glycemia to coronary heart disease in subjects with type 2 diabetes is controversial. Recent data have suggested a significant relation of glycemia to cardiovascular disease in both type 2 diabetes and in subjects with impaired glucose tolerance, although the relation of glycemia to cardiovascular disease appears to be weaker than the relation of glycemia to microvascular disease.     

A comparison of the effects of rosiglitazone and glyburide on cardiovascular function and glycemic control in patients with type 2 diabetes

OBJECTIVE: This open-label, active-controlled study investigated the cardiac safety and antihyperglycemic effect of rosiglitazone (RSG) in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: Of the 203 patients randomly assigned to RSG (4 mg b.i.d.) or glyburide (GLB) (titrated to achieve optimal glycemic control for the first 8 weeks only to limit the risk of hypoglycemia; mean 10.5 mg/day), 118 had an echocardiogram performed at week 52. Left ventricular (LV) mass index, ejection fraction, and left ventricular end-diastolic volume were assessed by M-mode echocardiography at baseline and weeks 12, 28, and 52; 24-h ambulatory blood pressure was assessed at baseline and at weeks 28 and 52. Glycemic control was assessed by measuring fasting plasma glucose (FPG) and HbA(1c). RESULTS: Neither treatment produced an increase in LV mass index that exceeded 1 SD. Ejection fraction did not change in either group. Both groups had clinically insignificant increases in LV end-diastolic volume. RSG, but not GLB, caused a statistically significant reduction in ambulatory diastolic blood pressure. Both treatments reduced HbA(1c) and FPG. CONCLUSIONS: A total of 52 weeks of therapy with RSG (4 mg b.i.d.) did not adversely affect cardiac structure or function in patients with type 2 diabetes and produced significant and sustained reductions in hyperglycemia. Decreases in ambulatory diastolic blood pressure with RSG were superior to those with GLB.     

Pioglitazone hydrochloride monotherapy improves glycemic control in the treatment of patients with type 2 diabetes: a 6-month randomized placebo-controlled dose-response study. The Pioglitazone 001 Study Group

OBJECTIVE: To evaluate the efficacy and safety of four doses of pioglitazone monotherapy in the treatment of patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: There were 408 patients randomized in this multicenter double-blind placebo-controlled clinical trial. Patients who had HbA1c > or = 7.0%, fasting plasma glucose (FPG) > or = 140 mg/dl, and C-peptide > 1 ng/ml were randomized to receive placebo or 7.5, 15, 30, or 45 mg pioglitazone administered once a day for 26 weeks. RESULTS: Patients treated with 15, 30, or 45 mg pioglitazone had significant mean decreases in HbA1c (range -1.00 to -1.60% difference from placebo) and FPG (-39.1 to -65.3 mg/dl difference from placebo). The decreases in FPG were observed as early as the second week of therapy; maximal decreases occurred after 10-14 weeks and were maintained until the end of therapy (week 26). In the 15-, 30-, or 45-mg pioglitazone groups, there were significant mean percent decreases in triglycerides, significant mean percent increases in HDL cholesterol, and only small percent changes in total cholesterol and LDL. The subset of patients naive to therapy had greater improvements in HbA1c and FPG (difference from placebo of -2.55% and -79.9 mg/dl for the 45-mg group) compared with previously treated patients. The overall adverse event profile of pioglitazone was similar to that of placebo. There was no evidence of drug-induced hepatotoxicity or drug-induced elevations of alanine aminotransferase levels in this study CONCLUSIONS: Pioglitazone monotherapy significantly improves HbA1c and FPG while producing beneficial effects on serum lipids in patients with type 2 diabetes with no evidence of drug-induced hepatotoxicity.     

Effect of the dipeptidyl peptidase-4 inhibitor sitagliptin as monotherapy on glycemic control in patients with type 2 diabetes

OBJECTIVE: To examine the efficacy and safety of once-daily oral sitagliptin as monotherapy in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: In a randomized, double-blind, placebo-controlled study, 741 patients (baseline HbA(1c) [A1C] 8.0%) were randomized to sitagliptin 100 or 200 mg or placebo for 24 weeks. RESULTS: Sitagliptin 100 and 200 mg produced significant (P < 0.001) placebo-subtracted reductions in A1C (-0.79 and -0.94%, respectively) and fasting plasma glucose (-1.0 mmol/l [-17.1 mg/dl] and -1.2 mmol/l [-21.3 mg/dl], respectively). Patients with baseline A1C >or=9% had greater reductions in placebo-subtracted A1C with sitagliptin 100 and 200 mg (-1.52 and -1.50%, respectively) than those with baseline A1C <8% (-0.57 and -0.65%) or >or=8 to <9.0% (-0.80 and -1.13%, respectively). In a meal tolerance test, sitagliptin 100 and 200 mg significantly decreased 2-h postprandial glucose (PPG) (placebo-subtracted PPG -2.6 mmol/l [-46.7 mg/dl] and -3.0 mmol/l [-54.1 mg/dl], respectively). Results for the above key efficacy parameters were not significantly different between sitagliptin doses. Homeostasis model assessment of beta-cell function and proinsulin-to-insulin ratio improved with sitagliptin. The incidence of hypoglycemia was similar, and overall gastrointestinal adverse experiences were slightly higher with sitagliptin. No meaningful body weight changes from baseline were observed with sitagliptin 100 (-0.2 kg) or 200 mg (-0.1 kg). The body weight change with placebo (-1.1 kg) was significantly (P < 0.01) different from that observed with sitagliptin. CONCLUSIONS: In this 24-week study, once-daily sitagliptin monotherapy improved glycemic control in the fasting and postprandial states, improved measures of beta-cell function, and was well tolerated in patients with type 2 diabetes.     

Clinical interpretation of indices of quality of glycemic control and glycemic variability

The practicing physician is faced with the task of interpreting>2 dozen indices of quality of glycemic control and glycemic variability. It would be desirable to have reference data from relevant patient populations (eg, patients with the same type of diabetes, duration of diabetes, therapeutic regimen, or glycated hemoglobin [HbA1c] levels). The physician can then select the appropriate reference set for interpretation of results for each patient. Institutions and clinics may wish to develop their own reference data. Results can be interpreted as excellent, good, fair, or poor, corresponding with quartiles of their distributions. Each index of glycemic control and variability can be given a numerical score in terms of its percentile within the selected reference population. One can then compute the mean and standard deviation of the percentile scores to obtain an integrated measure of the quality of glycemic control or variability. We calculated quartiles for measures of quality of glycemic control and variability. One can use the percent coefficient of variation (%CV) with criteria that apply irrespective of the HbA1c level as a general rule for interpretation of glycemic variability. For example, a %CV<33.5% can be regarded as excellent, a %CV between 33.5% to 36.8% as good, a %CV between 36.8% to 40.6% as fair, and a %CV>40.6% as poor. A graphical display can be used to make more accurate assessments for narrow HbA1c ranges, as the percentiles of the %CV can change systematically with HbA1c level or with mean glucose level.     

Effects of metformin and rosiglitazone monotherapy on insulin-mediated hepatic glucose uptake and their relation to visceral fat in type 2 diabetes

OBJECTIVE: Impaired insulin-mediated hepatic glucose uptake (HGU) has been implicated in the hyperglycemia of type 2 diabetes. We examined the effects of metformin (2 g/day) and rosiglitazone (8 mg/day) monotherapy on HGU and its relation to subcutaneous fat, visceral fat (VF), and whole-body insulin-mediated glucose metabolism in type 2 diabetic patients. RESEARCH DESIGN AND METHODS: Glucose uptake was measured before and after 26 weeks of treatment using positron emission tomography with [(18)F]2-fluoro-2-deoxyglucose during euglycemic hyperinsulinemia; fat depots were quantified by magnetic resonance imaging. RESULTS: Fasting plasma glucose levels were significantly decreased after either rosiglitazone (-0.9 +/- 0.5 mmol/l) or metformin treatment (-1.1 +/- 0.5 mmol/l) in comparison with placebo; only metformin was associated with weight loss (P < 0.02 vs. placebo). When controlling for the latter, the placebo-subtracted change in whole-body glucose uptake averaged -1 +/- 4 micromol x min(-1) x kg(-1) in metformin-treated patients (NS) and +9 +/- 3 micromol x min(-1) x kg(-1) in rosiglitazone-treated patients (P = 0.01). Both rosiglitazone and metformin treatment were associated with an increase in HGU; versus placebo, the change reached statistical significance when controlling for sex (placebo-subtracted values = +0.008 +/- 0.004 micromol x min(-1) x kg(-1) x pmol/l(-1), P < 0.03, for metformin; and +0.007 +/- 0.004, P < 0.07, for rosiglitazone). After treatment with either drug, insulin-mediated VF glucose uptake (VFGU) was higher than with placebo. In the whole dataset, changes in HGU were negatively related to changes in HbA(1c) (r = 0.43, P = 0.01) and positively associated with changes in VFGU (r = 0.48, P < 0.01). CONCLUSIONS: We conclude that both metformin and rosiglitazone monotherapy increase HGU in type 2 diabetes; direct drug actions, better glycemic control, and enhanced VF insulin sensitivity are likely determinants of this phenomenon.