Combination therapy with metformin plus vildagliptin in type 2 diabetes mellitus

Introduction: Type 2 diabetes mellitus (T2DM) is pathophysiologically characterized by a combination of insulin resistance and beta-cell dysfunction. Consequently, a proper treatment of such a disease should target both of these defects. Dipeptidyl peptidase-4 (DPP-4) inhibitors are among the most recent additions to the therapeutic options for T2DM and are able to increase circulating levels of glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), thus stimulating glucose-dependent insulin secretion.

Areas covered: This paper provides an overview of the clinical results of combination therapy with metformin and the DPP-4 inhibitor vildagliptin in T2DM patients.

Expert opinion: Vildagliptin–metformin single-tablet combination is indicated for the treatment of T2DM patients not achieving a sufficient glycemic control at their maximally tolerated dose of metformin. Results from clinical trials provide evidence of vildagliptin efficacy administered in addition to metformin, as either first- or second-line treatment. The vildagliptin–metformin association seems to have favorable effects on beta-cell function and is characterized by good safety and tolerability profiles when compared with other antidiabetic agents. Of note, data available suggest that administration of fixed-dose combination products, together with the low incidence of adverse gastrointestinal events, may improve compliance and adherence of patients to therapy, resulting in an improved metabolic control.     

Sitagliptin/metformin fixed-dose combination: in patients with type 2 diabetes mellitus

Sitagliptin/metformin is a single-tablet, fixed-dose combination of the dipeptidyl peptidase-4 inhibitor sitagliptin and the biguanide antihyperglycaemic metformin that achieves greater improvements in glycaemic control than either component alone in patients with type 2 diabetes mellitus. Recommended dosages of sitagliptin plus metformin, either as the fixed-dose tablet or a combination of the individual agents, significantly reduced glycosylated haemoglobin (HbA(1c)) levels in two well designed clinical trials in treatment-naive patients with type 2 diabetes. The improvements in glycaemic control seen with sitagliptin plus metformin therapy after 18 or 24 weeks were greater than those observed with the individual components alone and/or placebo, and sustained over treatment durations of up to 2 years. As add-on therapy in treatment-experienced patients with inadequate glycaemic control, the HbA(1c)-lowering efficacy of sitagliptin plus metformin was noninferior to that of glimepiride plus metformin in a 30-week, double-blind trial. Sitagliptin plus metformin and glipizide plus metformin lowered HbA(1c) levels by generally similar magnitudes, with the noninferiority of sitagliptin plus metformin to glipizide plus metformin being established in one 52-week study. As part of triple combination therapy, also in treatment-experienced patients with inadequate glycaemic control, sitagliptin added to ongoing glimepiride with or without metformin or ongoing insulin with or without metformin significantly improved glycaemic control over 24 weeks. Sitagliptin plus metformin, as the fixed-dose tablet or a combination of the individual agents, was generally well tolerated in patients with type 2 diabetes, and was associated with a low risk of hypoglycaemia.     

A randomized,double-blind,placebo-controlled trial evaluating sitagliptin action on insulin resistance parameters and β-cell function

Aim: To evaluate the impact on glycemic control, insulin secretion and on insulin resistance of a sitagliptin + metformin combination compared to metformin monotherapy in type 2 diabetic, naïve to treatment, patients.

Materials and methods: A total of 178 Caucasian type 2 diabetic patients were randomized to take sitagliptin 100 mg once a day or placebo in addition to previously taken metformin, for 12 months. The authors evaluated at 3, 6, 9, and 12 months: body mass index (BMI), glycemic control, fasting plasma insulin (FPI), HOMA-IR, HOMA-β, fasting plasma proinsulin (FPPr), proinsulin/fasting plasma insulin ratio (Pr/FPI ratio), C-peptide, glucagon, retinol binding protein-4 (RBP-4), visfatin, and chemerin. Before and 12 months after the addition of sitagliptin, patients underwent tests to assess insulin sensitivity and insulin secretion.

Results: Sitagliptin + metformin gave a better decrease of glycemic control, HOMA-IR and glucagon levels compared to placebo + metformin; sitagliptin + metformin also better increased HOMA-β and all β-cell measurements recorded after the clamp. Regarding adipocytokines, sitagliptin + metformin better reduced RBP-4, visfatin and chemerin levels, compared to placebo + metformin.

Conclusion: When metformin alone is not enough to reach an adequate glycemic control, sitagliptin can be a valid option, because of its effects in reducing insulin resistance and in preserving β-cell function.     

Effects of sitagliptin or mitiglinide as an add-on to acarbose on daily blood glucose fluctuations measured by 72 h subcutaneous continuous glucose monitoring in Japanese patients with type 2 diabetes: a prospective randomized study

Objective: Postprandial hyperglycemia and blood glucose fluctuations increase the risk of macroangiopathy in patients with type 2 diabetes mellitus (T2DM). However, few studies have examined the effects of oral hypoglycemic drugs on blood glucose fluctuations in daily life.

Methods: Twenty-nine T2DM patients treated with acarbose were randomized to receive either sitagliptin (14 patients) or mitiglinide (15 patients) together with acarbose for 4 weeks. Patients were then switched to a combination of 10 mg mitiglinide and 0.2 mg voglibose for 4 weeks. All patients wore a continuous glucose monitoring (CGM) device for 5 – 7 days in week 3 of each treatment period.

Results: The percentage of blood glucose levels in the hyperglycemic range, blood glucose indices derived from 24-h CGM profiles and the glycemic parameters (HbA1c, glycated albumin and fasting plasma glucose) were significantly improved by adding sitagliptin or mitiglinide to ongoing acarbose therapy. These parameters also tended to improve in the mitiglinide/voglibose combination period.

Conclusion: Daily blood glucose fluctuations were significantly improved by adding sitagliptin or mitiglinide to acarbose, and improved after switching to the mitiglinide/voglibose combination. Larger controlled studies are needed to verify the effects of adding sitagliptin or mitiglinide to acarbose on glucose fluctuations.     

The development of an oralantidiabetic combination tablet: design,evaluation and clinicalbenefits for patients with type 2diabetes

SUMMARY

Type 2 diabetes is a chronic and progressive disease. Oral antidiabetic monotherapies directly address only one defect as their primary mechanism of action, and do not control blood glucose sufficiently well to meet current glycaemic targets. In consequence, most patients need combination therapy within a few years. However, the co-administration of two or more oral antidiabetic drugs may render treatment regimens difficult to follow. Combining oral antidiabetic agents into a single tablet provides a means of intensifying antidiabetic therapy while supporting good patient compliance. An insulin sensitiser and an insulin secretagogue represent a rational oral antidiabetic combination, as they address the dual endocrine defects of insulin resistance and impaired β-cell function in type 2 diabetes. Nevertheless, the components of a combination tablet must be carefully chosen. Metformin (aninsulin sensitiser) and glibenclamide (an insulin secretagogue) are well supported by decades of clinical evidence, and the pharmacokinetics of these agents support twice-daily co-administration. The final technical challenge is to optimise their delivery within a single-tablet combination. A recently-introduced metformin-glibenclamide combination tablet (Glucovancet) has been extensively studied in well-designed clinical trials, where it has been shown to be more effective than its component monotherapies in controlling fasting and postprandial glycaemia. This treatment provides a case study in the development of a single-tablet oral antidiabetic combination, in terms of the pharmacokinetic issues facing the development of this preparation, and the implications of the pharmacokinetic properties of the components of the combination tablet on their pharmacodynamic actions and risk-benefit profile.     

A randomized clinical trial of the safety and efficacy of sitagliptin in patients with type 2 diabetes mellitus inadequately controlled by acarbose alone

Objective: To evaluate the safety and efficacy of sitagliptin when added to the treatment of patients with type 2 diabetes mellitus (T2DM) and inadequate glycemic control on acarbose monotherapy.

Research design and methods: This was a multicenter, randomized, placebo-controlled, double-blind clinical trial. Patients (N?=?381) with T2DM and inadequate glycemic control (glycated hemoglobin [HbA1c] ≥?7.0% and ≤10.0%) on acarbose monotherapy (at least 50?mg three times daily) were randomized in a 1:1 ratio to receive the addition of sitagliptin 100?mg or matching placebo once daily for 24 weeks.

Main outcome measures: Changes from baseline in HbA1c and fasting plasma glucose (FPG) at Week 24.

Results: The mean baseline HbA1c in randomized patients was 8.1%. At Week 24, the placebo-controlled, least squares mean changes from baseline (95% confidence interval) in HbA1c and FPG in the sitagliptin group were ?0.62% and ?0.8?mmol/L (p?p?Conclusions: Sitagliptin was generally well tolerated and provided statistically superior and clinically meaningful improvements in glycemic control after 24 weeks of treatment compared to placebo when added to treatment of patients with inadequate glycemic control on acarbose monotherapy.

Clinicaltrials.gov: NCT01177384.     

Glycemic/metabolic responses to identical meal tolerance tests at breakfast,lunch and dinner in Japanese patients with type 2 diabetes mellitus treated with a dipeptidyl peptidase-4 inhibitor and the effects of adding a mitiglinide/voglibose fixed-dose combination

Background: The effects of the mitiglinide/voglibose fixed-dose combination on postprandial glycemic/metabolic responses in patients with type 2 diabetes mellitus (T2DM) treated with dipeptidyl peptidase-4 (DPP-4) inhibitors are unknown.

Methods: Twelve T2DM patients treated with a DPP-4 inhibitor underwent identical meal tolerance tests (MTTs) at breakfast, lunch and dinner, before and 2 – 3 weeks after treatment with a fixed-dose combination of mitiglinide 10 mg and voglibose 0.2 mg (combination). Patients were randomized in a cross-over fashion to administer the combination either three-times-daily before each meal or twice-daily before breakfast and dinner. Glycemic/metabolic responses were evaluated at 0, 30, 60 and 120 min in each MTT.

Results: Three-times-daily administration of the combination significantly suppressed postprandial hyperglycemia after each meal, particularly after lunch and dinner. Active glucagon-like peptide-1 levels increased significantly after each meal, as did early-phase insulin secretion without excessive insulin secretion. Postprandial hyperglycemia after lunch was significantly greater after twice-daily than three-times-daily administration, but there were no clinically relevant differences in other metabolic responses.

Conclusion: This study revealed that adding the mitiglinide/voglibose combination to a DPP-4 inhibitor elicited additive improvements in postprandial glycemic/metabolic responses assessed using MTTs at breakfast, lunch and dinner with identical meal compositions.     

磷酸西格列汀联合胰岛素治疗2型糖尿病疗效观察

目的 观察磷酸西格列汀联合胰岛素治疗2型糖尿病的临床疗效.方法 选取在我院接受胰岛素治疗至少8周的2型糖尿病患者20例,入选后测定身高、体重、空腹及餐后血糖、糖化血红蛋白值,记录胰岛素用量.给予磷酸西格列汀100mg/d口服,并根据定期血糖监测情况适时调整胰岛素用量,经过4周联合治疗后,观察患者BMI、空腹及餐后血糖、糖化血红蛋白值的变化.结果 联合磷酸西格列汀治疗4周后,患者HbA1c、FBG显著降低(P＜0.01);2hBG明显降低(P＜0.05);胰岛素用量较前明显减少(P＜0.01);BMI较前无明显改变(P＞0.05).结论 磷酸西格列汀联合胰岛素治疗2型糖尿病有明显疗效,且可以减少患者胰岛素用量,降低低血糖风险,降低体重,无明显胃肠道不良反应.     

Clinical effect of combination therapy of pioglitazone and an α-glucosidase inhibitor

SUMMARY

This study evaluated the efficacy of adding pioglitazone 30?mg to the therapy of patients with type 2 diabetes mellitus whose glycaemic control was poor on an α-glucosidase inhibitor (α-GI) alone or in combination with a sulphonylurea (SU).

The patients (n?=?20) had a HbA1c level between 7.0 and 12.0% and the fasting plasma glucose was 7.8?mmol?l^?1 or higher. They were treated with 30?mg pioglitazone once daily for 16 weeks.

The decrease in HbA1c at week 16 of treatment was 0.8% (7.8% at baseline dropping to 7.1% at week 16; p?<?0.01). An increase in leptin was observed 4 weeks after starting the post-study period (p?<?0.05). Tumour necrosis factor-α (TNF-α) and body fat percentage did not show any

significant alterations. Correlations between the decrease in HbA1c at week 16 and characteristic variables of patients were examined. A correlation with leptin (p?=??0.5632, p?<?0.05) levels was found. Five patients experienced adverse drug reactions, such as oedema, hypoglycaemia and increased creatine phosphokinase (CK), all of which were mild in severity.

The addition of pioglitazone in diabetics whose glycaemic control was poor on a α-GI alone or with a α-GI and SU combination resulted in a significant decrease in HbA1c, and the treatment was well-tolerated. Our findings also suggest that leptin levels could be useful for assessing responders to pioglitazone.     

Efficacy and safety of therapy with metformin plus pioglitazone in the treatment of patients with type 2 diabetes: a double-blind,placebo-controlled,clinical trial

ABSTRACT

Objective: To assess the efficacy and safety of combination therapy with pioglitazone and metformin in Japanese patients with type 2 diabetes.

Research design and methods: During a 12-week observation period 236 patients were treated with metformin 500 or 750?mg/day. 169 patients with a confirmed HbA_1c level ≥ 6.5% were randomized (stratified according to metformin dosage) to receive pioglitazone 15?mg/day for 12 weeks then increased to 30?mg/day for a further 16 weeks (n?=?83), or placebo (n?=?86). Outcome measures included HbA_1c, fasting blood glucose (FBG), percentage of patients achieving HbA_1c?<?6.5%, lipid profile, and other metabolic parameters.

Results: Mean HbA_1c was reduced by 0.67% in patients receiving pioglitazone plus metformin versus an increase of 0.25% in those receiving metformin alone (p?<?0.0001). After 8 weeks’ treatment and until the end of the study, HbA_1c was significantly lower with pioglitazone plus metformin and more patients in this group achieved an HbA_1c?<?6.5% (38.6% vs. 8.1%; p?<?0.0001). FBG was also reduced by a significantly greater amount in patients receiving pioglitazone plus metformin compared with metformin monotherapy (?20.5 vs. 1.9?mg/dl; p?<?0.0001). Combination therapy was associated with significantly increased HDL-cholesterol, total cholesterol, and adiponectin, and significantly decreased levels of fasting insulin, free fatty acids, and homeostasis model assessment insulin resistance (HOMA-R) compared with metformin monotherapy. Overall, combination therapy and monotherapy were equally well tolerated and the incidence of adverse effects ‘possibly’ related to therapy was 15.7% and 11.6% (p?=?0.505), respectively. Edema occurred slightly more often in the combination group (6.0 vs. 1.2%).

Conclusion: Pioglitazone plus metformin significantly improved glycemic control (HbA_1c and FBG), and markers associated with increased insulin resistance and cardiovascular risk compared with metformin monotherapy.

Clinical trial registration number: UMIN 000001110.     

Combination therapy for type 2 diabetes: dapagliflozin plus metformin

Introduction: Type 2 diabetes (T2D) is a chronic and multifactorial metabolic disease, which brings great threats to public health. The morbidity of T2D keeps growing, and it is estimated that the population with T2D will rise to 552 million throughout the world by 2030. Effective glycemic control in patients is crucial for the treatment of T2D. However, with progressive deterioration of disease, most patients are usually unable to achieve glycemic targets receiving antidiabetic agent monotherapy. In such cases, combination therapy with different mechanisms of antidiabetic agents is highly desired. In addition, combination therapy can provide advantages beyond better glycemic improvement such as reduced incidence of hypoglycemia and cardiovascular events.

Areas covered: We reviewed all the published data regarding the fixed-dose combination therapy of dapagliflozin combined with metformin, including complementary mechanism of action, pharmacodynamics, pharmacokinetics, clinical efficacy and safety.

Expert opinion: The fixed-dose combination of dapagliflozin and metformin exerts synergistic effects based on two antidiabetic agents with complementary mechanisms of action. Rational co-administration of dapagliflozin and metformin provides better glycemic control with potential weight loss and the reduced incidence of hypoglycaemia.     

Sitagliptin

Sitagliptin, an oral dipeptidyl peptidase-4 (DPP-4) inhibitor, improves glycaemic control by inhibiting DPP-4 inactivation of the incretin hormones glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide. This increases active incretin and insulin levels, and decreases glucagon levels and post-glucose-load glucose excursion. In large, well designed phase III trials in patients with type 2 diabetes mellitus, sitagliptin 100 or 200mg once daily alone or in combination with other antihyperglycaemics was associated with significant improvements relative to placebo in overall glycaemic control and indices for insulin response and beta-cell function. Improvements from baseline in mean glycosylated haemoglobin (HbA(1c)) were significantly greater with sitagliptin monotherapy than with placebo in patients with type 2 diabetes. As add-on therapy in patients with suboptimal glycaemic control despite oral antihyperglycaemic treatment, sitagliptin improved HbA(1c) to a significantly greater extent than placebo when added to metformin or pioglitazone and was noninferior to glipizide when added to metformin. Sitagliptin was well tolerated when administered alone or in combination with other antihyperglycaemics, with an adverse event profile similar to that shown with placebo. The incidence of hypoglycaemia with sitagliptin was similar to that with placebo and, in combination with metformin, lower than that with glipizide. Sitagliptin had a generally neutral effect on bodyweight.     

Comparing postprandial efficacy in type 2 diabetic patients receiving mitiglinide and sitagliptin by using continuous glucose monitoring: a pilot study

Objective: To compare postprandial efficacy in type 2 diabetic patients given mitiglinide and sitagliptin, both of which are known to improve postprandial hyperglycemia, by using continuous glucose monitoring (CGM).

Methods: Eleven patients with type 2 diabetes were given mitiglinide 10 mg three times a daily or sitagliptin 50 mg once a day for 1 month and were hospitalized for 4 days and evaluated by CGM. On discharge, they were crossed over to the other regimen for 1 month of treatment/4 days of evaluation. The CGM data were used to compare each parameter for glycemic variability.

Results: The patients were 60 ± 10 (mean ± SD) years old, and had HbA1c value 7.3 ± 0.9%. The pre-meal glucose levels before lunch were significantly lower with mitiglinide than with sitagliptin (116 ± 26/131 ± 34 mg/dl, p = 0.022). The AUC measuring over 140 mg/dl 3 h after breakfast (mitiglinide 4812 ± 4219/sitagliptin 7807 ± 6391 mg/dl·min, p = 0.042) and lunch (mitiglinide 5658 ± 5856/sitagliptin 8492 ± 7161, p = 0.050) was significantly lower with mitiglinide than with sitagliptin.

Conclusions: A CGM-based comparison showed that mitiglinide and sitagliptin were different in their glucose-lowering effects, where mitiglinide significantly improved hyperglycemia after breakfast and lunch, and significantly lowered pre-meal glucose levels before lunch, compared to sitagliptin.     

Effects of exenatide versus sitagliptin on postprandial glucose,insulin and glucagon secretion,gastric emptying,and caloric intake: a randomized,cross-over study

ABSTRACT

Background: This study evaluated the effects of exenatide, a GLP-1 receptor agonist, and sitagliptin, a DPP-4 inhibitor, on 2-h postprandial glucose (PPG), insulin and glucagon secretion, gastric emptying, and caloric intake in T2D patients.

Methods: This double-blind, randomized cross-over, multi-center study was conducted in metformin-treated T2D patients: 54% female; BMI: 33?±?5?kg/m²; HbA_1c: 8.5?±?1.2%; 2-h PPG: 245?±?65?mg/dL. Patients received exenatide (5?µg BID for 1 week, then 10?µg BID for 1 week) or sitagliptin (100?mg QAM) for 2 weeks. After 2 weeks, patients crossed-over to the alternate therapy. Postprandial glycemic measures were assessed via standard meal test; caloric intake assessed by ad libitum dinner (subset of patients). Gastric emptying was assessed by acetaminophen absorption (Clinicaltrials.gov Registry Number: NCT00477581).

Results: After 2 weeks of therapy, 2-h PPG was lower with exenatide versus sitagliptin: 133?±?6?mg/dL versus 208?±?6?mg/dL, p?<?0.0001 (evaluable, N?=?61). Switching from exenatide to sitagliptin increased 2-h PPG by +73?±?11?mg/dL, while switching from sitagliptin to exenatide further reduced 2-h PPG by ?76?±?10?mg/dL. Postprandial glucose parameters (AUC, C_ave, C_max) were lower with exenatide than sitagliptin (p?<?0.0001). Reduction in fasting glucose was similar with exenatide and sitagliptin (?15?±?4?mg/dL vs. ?19?±?4?mg/dL, p?=?0.3234). Compared to sitagliptin, exenatide improved the insulinogenic index of insulin secretion (ratio exenatide to sitagliptin: 1.50?±?0.26, p?=?0.0239), reduced postprandial glucagon (AUC ratio exenatide to sitagliptin: 0.88?±?0.03, p?=?0.0011), reduced postprandial triglycerides (AUC ratio exenatide to sitagliptin: 0.90?±?0.04, p?=?0.0118), and slowed gastric emptying (acetaminophen AUC ratio exenatide to sitagliptin: 0.56?±?0.05, p?<?0.0001). Exenatide reduced total caloric intake compared to sitagliptin (?134?±?97?kcal vs. +130?±?97?kcal, p?=?0.0227, N?=?25). Common adverse events with both treatments were mild to moderate in intensity and gastrointestinal in nature.

Conclusions: Although this study was limited by a 2-week duration of exposure, these data demonstrate that, exenatide had: (i) a greater effect than sitagliptin to lower postprandial glucose and (ii) a more potent effect to increase insulin secretion and reduce postprandial glucagon secretion in T2D patients. In contrast to sitagliptin, exenatide slowed gastric emptying and reduced caloric intake. These key findings differentiate the therapeutic actions of the two incretin-based approaches, and may have meaningful clinical implications.     

Efficacy and safety of initial combination therapy with sitagliptin and metformin in patients with type 2 diabetes: a 54-week study

ABSTRACT

Objective: To assess the 54-week efficacy and safety of initial combination therapy with sitagliptin and metformin in patients with type 2 diabetes and inadequate glycemic control (HbA_1c 7.5–11%) on diet and exercise.

Methods and materials: This was multinational study conducted at 140 clinical sites in 18 countries. Following an initial 24-week, double-blind, placebo-controlled period, patients entered a double-blind continuation period for an additional 30 weeks. Following the week 24 evaluation, patients remained on their previously assigned active, oral treatments: sitagliptin 50?mg b.i.d.?+?metformin 1000?mg b.i.d. (S100?+?M2000), sitagliptin 50?mg b.i.d.?+?metformin 500?mg b.i.d. (S100?+?M1000), metformin 1000?mg b.i.d. (M2000), metformin 500?mg b.i.d. (M1000), and sitagliptin 100?mg q.d. (S100). Patients initially randomized to placebo were switched to M2000 (designated PBO/M2000) at week 24. This report summarizes the overall safety and tolerability data for the 54-week study and presents efficacy results for patients randomized to continuous treatments who entered the 30-week continuation period.

Results: Of the 1091 randomized patients, 906 completed the 24-week placebo-controlled phase and 885 patients continued into the 30-week continuation period (S100?+?M2000 n?=?161, S100+M1000 n?=?160, M2000 n?=?153, M1000 n?=?147, S100 n?=?141, PBO/M2000 n?=?123). At baseline, patients included in the efficacy analysis had mean age of 54 years, mean BMI of 32?kg/m², mean HbA_1c of 8.7% (8.5–8.8% across groups), and mean duration of type 2 diabetes of 4 years. At week 54, in the all-patients-treated analysis of continuing patients, least-squares (LS) mean changes in HbA_1c from baseline were ?1.8% (S100?+?M2000), ?1.4% (S100?+?M1000), ?1.3% (M2000), ?1.0% (M1000), and ?0.8% (S100). The proportions of continuing patients with an HbA_1c?<?7% at week 54 were 67% (S100?+?M2000), 48% (S100?+?M1000), 44% (M2000), 25% (M1000), and 23% (S100). For the patients completing treatment through week 54, LS mean changes in HbA_1c from baseline were ?1.9% (S100?+?M2000), ?1.7% (S100?+?M1000), ?1.6% (M2000), ?1.2% (M1000), and ?1.4% (S100). Glycemic response was generally durable over time across treatments. All treatments improved measures of β-cell function (e.g., HOMA-β, proinsulin/insulin ratio). Mean body weight decreased from baseline in the combination and metformin monotherapy groups and was unchanged from baseline in the sitagliptin monotherapy group. The incidence of hypoglycemia was low (1–3%) across treatment groups. The incidence of gastrointestinal adverse experiences with the co-administration of sitagliptin and metformin was similar to that observed with metformin alone.

Limitations: The patient population evaluated in the 54-week efficacy analysis was a population of patients who entered the continuation period without receiving glycemic rescue therapy in the 24-week placebo-controlled period. Because the baseline HbA_1c inclusion criteria ranged from 7.5 to 11% and the glycemic rescue criterion was an HbA_1c?>?8% after week 24, there was a greater likelihood of glycemic rescue in the monotherapy groups; this led to more missing data in the continuation all-patients-treated population(CAPT) analysis and fewer patients contributing to the completers analysis in the monotherapy groups.

Conclusions: In this study, initial treatment with sitagliptin, metformin, or the combination therapy of sitagliptin and metformin provided substantial and durable glycemic control, improved markers of β-cell function, and was generally well-tolerated over 54 weeks in patients with type 2 diabetes.     

Pharmacokinetic drug evaluation of empagliflozin plus linagliptin for the treatment of type 2 diabetes

Introduction: Type 2 diabetes mellitus has become a growing epidemic and therefore efficient treatment strategies that target its management are needed. The treatment of diabetic patients often requires the combination of antidiabetic drug classes. Sodium-glucose co-transporter 2 inhibitors (SGLT2i) block glucose reabsorption in the proximal renal tubules. Dipeptidyl peptidase-4 inhibitors (DPP-4i) improve glucose metabolism by blocking the enzyme that degrades incretins leading to increased insulin secretion.

Areas covered: The aim of the review is to present the available data on pharmacokinetic properties/pharmacodynamics, metabolic and cardiovascular effects of empagliflozin plus linagliptin combination.

Expert opinion: Both empagliflozin and linagliptin have established safety and efficacy in the treatment of diabetes. Available data demonstrate the absence of pharmacological interactions when the two drugs are given together. The complementary mechanisms of action would be expected to provide additive benefits on carbohydrate metabolism variables, but the results from clinical trials have shown that the empagliflozin/linagliptin combination provides only mild improvements of glycated hemoglobin compared with either monotherapy. However, the single-tablet formulation of empagliflozin/linagliptin is expected to provide better compliance and thus improved glycaemic control coupled with a favourable safety profile. Thus, the fixed-dose combination of empagliflozin/linagliptin has the capacity to both effectively and safely manage diabetic patients.     

Pioglitazone, rosiglitazone, and rosiglitazone + metformin: new drugs. Glitazone + oral antidiabetic combination: inadequately evaluated

(1) When single-agent therapy provides inadequate glycaemic control for patients with type 2 diabetes, most guidelines recommend metformin in combination with a glucose-lowering sulphonylurea as standard treatment, despite the lack of any proven impact on morbidity or mortality. Other options include switching to insulin or abandoning the target of strict glycaemic control. (2) Pioglitazone and rosiglitazone are approved for use in combination with a glucose-lowering sulphonylurea when metformin is poorly tolerated or contraindicated, and in combination with metformin in overweight patients. (3) A fixed-dose combination containing 1 or 2 mg of rosiglitazone plus 500 mg of metformin (hydrochloride) was launched onto the French market in October 2004. (4) The indication for rosiglitazone was extended to include its use as triple-agent therapy in combination with metformin and a glucose-lowering sulphonylurea. (5) No clinical trials assessing effects on mortality or morbidity have evaluated rosiglitazone or pioglitazone in combination with other oral antidiabetic drugs. (6) Several trials have compared the glucose-lowering effects of dual-agent therapy using rosiglitazone or pioglitazone plus a glucose-lowering sulphonylurea or metformin versus dual-agent therapy with metformin and a glucose-lowering sulphonylurea. (7) These clinical trials indicate that in terms of HbA1c level, dual-agent therapy based on rosiglitazone or pioglitazone is about as effective as combination therapy with metformin plus a glucose-lowering sulphonylurea. (8) The main known adverse effect of pioglitazone and rosiglitazone is water-sodium retention, which can provoke oedema and haemodilution anaemia, and can aggravate or reveal heart failure. (9) Pioglitazone has a positive effect on the lipid profile, whereas rosiglitazone increases the LDL-cholesterol level. (10) Dual-agent therapy with pioglitazone and a sulphonylurea causes more weight gain than metformin plus a sulphonylurea. (11) Several trials have assessed triple-agent regimens containing a glitazone. Three placebo-controlled double-blind trials have tested pioglitazone (one trial, nearly 300 patients) or rosiglitazone (two trials, about 1200 patients) for 12 to 26 weeks in patients whose glycaemia was poorly controlled by dual-agent therapy with a sulphonylurea plus metformin. The glycated haemoglobin level fell by 0.3% to 1.1% (in absolute values), depending on the trial and the dosage, but at a cost of the usual adverse effects such as weight gain, anaemia and oedema. Three unblinded trials have compared oral triple-agent regimens containing glitazone versus insulin plus metformin, alone or in combination with a glucose-lowering sulphonylurea; the treatment including glitazone was no more effective in terms of the glycated haemoglobin level, but was associated with an increase in adverse effects and dropouts. (12) Given the limited clinical data available in early 2005, pioglitazone and rosiglitazone have no place in the management of type 2 diabetes.     

Clinical effectiveness and safety evaluation of long-term pioglitazone treatment for erythropoietin responsiveness and insulin resistance in type 2 diabetic patients on hemodialysis

Background: We aimed to assess the effect of long-term pioglitazone treatment on erythropoietin responsiveness and insulin resistance in type 2 diabetic patients on hemodialysis.

Methods: We conducted a prospective, open-label, parallel-group, controlled study of 63 type 2 diabetic hemodialysis patients who were randomly assigned to two groups: pioglitazone group (P-group; 15 – 30 mg/day pioglitazone plus conventional oral hypoglycemic agents) and control group (C-group; conventional oral hypoglycemic agents alone). We determined the efficacy of pioglitazone by monitoring anemia, glycemic control, insulin resistance, and levels of inflammatory cytokines and high-molecular-weight (HMW) adiponectin for 96 weeks.

Results: Pioglitazone effectively reduced erythropoietin dose and maintained the target hemoglobin levels by improving insulin resistance up to the end of the study. In the P-group, hemoglobin A_1c, glycated albumin, and triglycerides significantly decreased compared with the C-group. There was a significant reduction in homeostasis model assessment for insulin resistance and the level of high-sensitivity C-reactive protein, and a significant increase in HMW adiponectin level in the P-group; these changes were significantly different compared with values for the C-group. No serious adverse effects such as hypoglycemia, liver impairment, or heart failure were observed in any of the patients.

Conclusion: Pioglitazone treatment resulted in better glycemic control, improved lipid levels, an increase in insulin sensitivity and adiponectin levels, and a decrease in inflammatory markers, thus improving the risk factors of cardiovascular disease. Erythropoietin responsiveness improved with a reduction in erythropoietin dose and may be associated with the improvement in insulin resistance due to long-term pioglitazone treatment.     

Pioglitazone is effective therapy for elderly patients with type 2 diabetes mellitus

BACKGROUND: Pioglitazone as monotherapy and in combination with sulfonylurea, metformin, or insulin has consistently demonstrated improved glycaemic and lipid parameters in patients with type 2 diabetes mellitus. OBJECTIVE: We performed a subanalysis to examine the effect of pioglitazone on glycaemia and lipids in patients <65 and > or =65 years of age in two double-blind, placebo-controlled monotherapy studies and in three separate multi-centre trials. METHOD: In Study 1, 197 patients were randomised to receive pioglitazone 30 mg/day or placebo for 16 weeks. Study 2 was a forced dose-titration trial in patients randomised to receive pioglitazone 7.5/15/30 mg/day, pioglitazone 15/30/45 mg/day, or placebo daily for 26 weeks. Each of the lower dosages was given for at least 4 weeks and the highest dosage for 16 weeks. The three combination studies evaluated efficacy of pioglitazone 30 or 45 mg/day over a 24-week period in combination with sulfonylureas, metformin, or insulin. RESULTS: In both placebo-controlled monotherapy studies, at 16 weeks, and at maximum pioglitazone dosage, 0.53-0.55% and 0.57-1.27% mean reductions from baseline in glycosylated haemoglobin (HbA(1c)) were seen in patients aged <65 (n = 225) and > or =65 (n = 45) years, respectively. There were statistically significant differences between the placebo and pioglitazone groups in each age cohort. Similar effects were observed in fasting plasma glucose (FPG) levels, with 2.03-2.59 mmol/L and 3.20-4.44 mmol/L mean reductions from baseline, respectively, which were significantly different from the changes in the placebo group, but there was no difference between pioglitazone groups. At treatment endpoint in combination trials, pioglitazone added to sulfonylurea produced a mean decrease in HbA(1c) of 0.78-1.61%, and 1.64-1.96% in patients aged <65 (n = 557) and > or =65 (n = 115) years, respectively. Pioglitazone added to metformin produced a mean decrease in HbA(1c) of 0.78-1.03% and 0.78-0.98% in patients aged <65 (n = 686) and > or =65 (n = 112) years, respectively. Pioglitazone added to insulin produced a mean decrease in HbA(1c) of 1.13-1.37% and 1.39-1.66% in patients aged <65 (n = 500) and > or =65 (n = 156) years, respectively. In patients aged > or =65 years, hypoglycaemia was observed in 1 of 14 patients and in 0 of 13 patients in the two monotherapy studies. In the combination studies, the incidence of hypoglycaemia among patients aged > or =65 years was as follows: 26.7-28.8% combined with sulfonylurea; 0-4.4% combined with metformin; and 53.4-56.4% combined with insulin. CONCLUSION: Pioglitazone monotherapy, or added to a sulfonylurea, metformin, or insulin demonstrated no significant differences in effectiveness while exhibiting similar adverse events in patients aged > or =65 years compared with patients aged <65 years. Well-controlled randomised clinical trials are recommended to confirm the impact of pioglitazone therapy on the glycaemic and lipid control in elderly patients with type 2 diabetes.     

Empagliflozin and linagliptin combination therapy for treatment of patients with type 2 diabetes mellitus

Introduction: Many patients with type 2 diabetes mellitus (T2DM) fail to achieve the desired A1c goal because the antidiabetic medications used do not correct the underlying pathophysiologic abnormalities and monotherapy is not sufficiently potent to reduce the A1c to the 6.5 – 7.0% range. Insulin resistance and islet (beta and alpha) cell dysfunction are major pathophysiologic abnormalities in T2DM. We examine combination therapy with linagliptin plus empagliflozin as a therapeutic approach for the treatment of inadequately controlled T2DM patients.

Areas covered: A literature search of all human diabetes, metabolism and general medicine journals from year 2000 to the present was conducted. Glucagon like peptide-1 (GLP-1) deficiency/resistance contributes to islet cell dysfunction by impairing insulin secretion and increasing glucagon secretion. DPP-4 inhibitors (DPP4i) improve pancreatic islet function by augmenting glucose-dependent insulin secretion and decreasing elevated plasma glucagon levels. Linagliptin, a DPP-4 inhibitor, reduces HbA1c, is weight neutral, has an excellent safety profile and a low risk of hypoglycemia. The expression of sodium-glucose cotransporter-2 (SGLT2) in the proximal renal tubule is upregulated in T2DM, causing excess reabsorption of filtered glucose. The SGLT2 inhibitor (SGLT2i), empagliflozin, improves HbA_1c by causing glucosuria and ameliorating glucotoxicity. It also decreases weight and blood pressure, and has a low risk of hypoglycemia.

Expert opinion: The once daily oral combination of linagliptin plus empagliflozin does not increase the risk of hypoglycemia and tolerability and discontinuation rates are similar to those with each as monotherapy. At HbA1c values below 8.5% linagliptin/empagliflozin treatment produces an additive effect, whereas above 8.5%, there is a less than additive reduction with combination therapy compared with the effect of each agent alone. Linagliptin/empagliflozin addition is a logical combination in patients with T2DM, especially those with an HbA1c < 8.5%.