Effect of Sitagliptin on Cardiovascular Outcomes in Type 2 Diabetes.

BACKGROUND: Data are lacking on the long-term effect on cardiovascular events of adding sitagliptin, a dipeptidyl peptidase 4 inhibitor, to usual care in patients with type 2 diabetes and cardiovascular disease. METHODS: In this randomized, double-blind study, we assigned 14,671 patients to add either sitagliptin or placebo to their existing therapy. Open-label use of antihyperglycemic therapy was encouraged as required, aimed at reaching individually appropriate glycemic targets in all patients. To determine whether sitagliptin was noninferior to placebo, we used a relative risk of 1.3 as the marginal upper boundary. The primary cardiovascular outcome was a composite of cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, or hospitalization for unstable angina. RESULTS: During a median follow-up of 3.0 years, there was a small difference in glycated hemoglobin levels (least-squares mean difference for sitagliptin vs. placebo, -0.29 percentage points; 95% confidence interval [CI], -0.32 to -0.27). Overall, the primary outcome occurred in 839 patients in the sitagliptin group (11.4%; 4.06 per 100 person-years) and 851 patients in the placebo group (11.6%; 4.17 per 100 person-years). Sitagliptin was noninferior to placebo for the primary composite cardiovascular outcome (hazard ratio, 0.98; 95% CI, 0.88 to 1.09; P<0.001). Rates of hospitalization for heart failure did not differ between the two groups (hazard ratio, 1.00; 95% CI, 0.83 to 1.20; P=0.98). There were no significant between-group differences in rates of acute pancreatitis (P=0.07) or pancreatic cancer (P=0.32). CONCLUSIONS: Among patients with type 2 diabetes and established cardiovascular disease, adding sitagliptin to usual care did not appear to increase the risk of major adverse cardiovascular events, hospitalization for heart failure, or other adverse events. (Funded by Merck Sharp & Dohme; TECOS ClinicalTrials.gov number, NCT00790205.).

Effects of meal size and composition on incretin, alpha-cell, and beta-cell responses.

The incretins glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) regulate postprandial insulin release from the beta-cells. We investigated the effects of 3 standardized meals with different caloric and nutritional content in terms of postprandial glucose, insulin, glucagon, and incretin responses. In a randomized crossover study, 18 subjects with type 2 diabetes mellitus and 6 healthy volunteers underwent three 4-hour meal tolerance tests (small carbohydrate [CH]-rich meal, large CH-rich meal, and fat-rich meal). Non-model-based and model-based estimates of beta-cell function and incremental areas under the curve of glucose, insulin, C-peptide, glucagon, GLP-1, and GIP were calculated. Mixed models and Friedman tests were used to test for differences in meal responses. The large CH-rich meal and fat-rich meal resulted in a slightly larger insulin response as compared with the small CH-rich meal and led to a slightly shorter period of hyperglycemia, but only in healthy subjects. Model-based insulin secretion estimates did not show pronounced differences between meals. Both in healthy individuals and in those with diabetes, more CH resulted in higher GLP-1 release. In contrast with the other meals, GIP release was still rising 2 hours after the fat-rich meal. The initial glucagon response was stimulated by the large CH-rich meal, whereas the fat-rich meal induced a late glucagon response. Fat preferentially stimulates GIP secretion, whereas CH stimulates GLP-1 secretion. Differences in meal size and composition led to differences in insulin and incretin responses but not to differences in postprandial glucose levels of the well-controlled patients with diabetes.

Classical and model-based estimates of beta-cell function during a mixed meal vs. an OGTT in a population-based cohort.

This study compared classical and model-based beta-cell responses during an oral glucose tolerance test (OGTT) and a meal tolerance test (MTT) in a population-based cohort. Individuals with normal glucose metabolism (NGM, n=161), impaired glucose metabolism (IGM, n=19) and type 2 diabetes mellitus (DM, n=20) underwent a 75 g-OGTT and an MTT (75 g carbohydrates, 50 g fat, 24 g proteins). Classical estimates of beta-cell function (insulinogenic index and the ratio of areas under insulin and glucose curves) were calculated. Mathematical modelling was used to determine beta-cell glucose sensitivity, rate sensitivity and potentiation. Insulin sensitivity was characterized by three surrogate estimates. Both classical and model-based estimates of beta-cell function were higher during MTT than during OGTT (P<0.05). Regarding the model-based parameters, especially beta-cell sensitivity was increased following MTT as compared with OGTT (P<0.05). Both during OGTT and MTT, across most parameters describing beta-cell function, the largest reduction in beta-cell response occurred between IGM and DM, while the largest reduction in insulin sensitivity occurred between NGM and IGM. We conclude that beta-cell response is stronger after a mixed meal than after an OGTT with equal carbohydrate quantity, both for classical and model-based parameters. The higher response was mostly explained by higher beta-cell sensitivity during the meal.

Efficacy and safety of sitagliptin in the treatment of patients with type 2 diabetes in China, India, and Korea.

The efficacy and safety of sitagliptin as monotherapy were evaluated in Chinese, Indian, and Korean patients with type 2 diabetes inadequately controlled by diet and exercise. In a randomized, placebo-controlled, double-blind, 18-week trial, 530 patients with HbA(1c) >or=7.5% and

Safety and tolerability of sitagliptin in patients with type 2 diabetes: a pooled analysis.

BACKGROUND: Sitagliptin, a highly selective dipeptidyl peptidase-4 inhibitor, is the first in a new class of oral antihyperglycemic agents (AHAs) for the treatment of patients with type 2 diabetes. Type 2 diabetes is a life-long disease requiring chronic treatment and management. Therefore, robust assessment of the long-term safety and tolerability of newer therapeutic agents is of importance. The purpose of this analysis was to assess the safety and tolerability of sitagliptin by pooling 12 large, double-blind, Phase IIb and III studies up to 2 years in duration. METHODS: This analysis included 6139 patients with type 2 diabetes receiving either sitagliptin 100 mg/day (N = 3415) or a comparator agent (placebo or an active comparator) (N = 2724; non-exposed group). The 12 studies from which this pooled population was drawn represent the double-blind, randomized, Phase IIB and III studies that included patients treated with the clinical dose of sitagliptin (100 mg/day) for at least 18 weeks up to 2 years and that were available in a single safety database as of November 2007. These 12 studies assessed sitagliptin as monotherapy, initial combination therapy with metformin, or add-on combination therapy with other oral AHAs (metformin, pioglitazone, sulfonylurea, sulfonylurea + metformin, or metformin + rosiglitazone). Patients in the non-exposed group were taking placebo, pioglitazone, metformin, sulfonylurea, sulfonylurea + metformin, or metformin + rosiglitazone. This safety analysis used patient-level data from each study to evaluate clinical and laboratory adverse experiences. RESULTS: For clinical adverse experiences, the incidence rates of adverse experiences overall, serious adverse experiences, and discontinuations due to adverse experiences were similar in the sitagliptin and non-exposed groups. The incidence rates of specific adverse experiences were also generally similar in the two groups, with the exception of an increased incidence rate of hypoglycemia observed in the non-exposed group. The incidence rates of drug-related adverse experiences overall and discontinuations due to drug-related adverse experiences were higher in the non-exposed group, primarily due to the increased incidence rate of hypoglycemia in this group. For cardiac- and ischemia-related adverse experiences (including serious events), there were no meaningful between-group differences. No meaningful differences between groups in laboratory adverse experiences, either summary measures or specific adverse experiences, were observed. CONCLUSION: In patients with type 2 diabetes, sitagliptin 100 mg/day was well tolerated in clinical trials up to 2 years in duration.

Sitagliptin, a DPP-4 inhibitor for the treatment of patients with type 2 diabetes: a review of recent clinical trials.

BACKGROUND: Dipeptidyl peptidase-4 (DPP-4) inhibitors are a new class of oral antihyperglycemic agents that enhance the body's ability to regulate blood glucose by increasing the active levels of incretins, glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP). There are numerous DPP-4 inhibitors in development with sitagliptin as the first approved agent for the treatment of patients with type 2 diabetes. OBJECTIVE: The purpose of this review is to provide an overview of the clinical trial results with sitagliptin. METHODS: Clinical trials published between January 2005 (first sitagliptin publication) and November 2007 were included in this review. Medline was searched using the search terms: MK-0431 or sitagliptin. FINDINGS: Sitagliptin, an oral, once-daily, and highly selective DPP-4 inhibitor, has been evaluated in clinical trials as monotherapy, as add-on therapy, or as initial combination therapy with metformin. Sitagliptin provided effective fasting and postprandial glycemic control in a wide range of patients with type 2 diabetes. Markers of beta-cell function (HOMA-beta and proinsulin/insulin ratio) were improved with sitagliptin treatment. In these clinical trials, sitagliptin was generally well tolerated with an overall incidence of adverse experiences comparable to placebo, a low risk of hypoglycemia or gastrointestinal adverse experiences, and a neutral effect on body weight. The findings presented in this review are limited to the specific patient population enrolled in each clinical trial and for durations for up to 1 year. Future clinical studies should evaluate whether this class of agents has the potential to delay progression and/or prevent type 2 diabetes. CONCLUSIONS: Sitagliptin has been shown to be effective and well-tolerated in various treatment regimens and may be considered for both initial therapy and as add-on therapy for patients with type 2 diabetes.

Efficacy and safety of sitagliptin added to ongoing metformin therapy in patients with type 2 diabetes.

OBJECTIVE: The purpose of this study was to evaluate the efficacy and safety of sitagliptin as an add-on to metformin therapy in patients with moderately severe (hemoglobin A(1c) >or= 8.0% and or= 6 weeks of stable metformin monotherapy (>or= 1500 mg/day), patients were randomized to either the addition of sitagliptin 100 mg once daily or placebo to ongoing metformin for 30 weeks. MAIN OUTCOME MEASURES: The primary efficacy endpoint was reduction in hemoglobin A(1c) (HbA(1c)) measured after 18 weeks of sitagliptin treatment. Key secondary endpoints included reduction in fasting plasma glucose (FPG) and 2-hour (2-h) postprandial plasma glucose (PPG) at 18 weeks, and HbA(1c) at 30 weeks. The proportion of patients meeting the goal of HbA(1c) < 7.0% was also analyzed. RESULTS: Sitagliptin significantly reduced HbA(1c), FPG, and 2-h PPG, compared with placebo (all p < 0.001). The net improvement in HbA(1c) was - 1.0% at both 18 and 30 weeks, and a significantly greater proportion of patients treated with sitagliptin achieved HbA(1c) < 7.0% by the end of the study (22.1% vs. 3.3%, p < 0.001). Sitagliptin was well-tolerated. Compared with placebo, sitagliptin had a neutral effect on body weight and did not significantly increase the risk of hypoglycemia or gastrointestinal adverse events. CONCLUSIONS: Addition of sitagliptin 100 mg once daily to ongoing metformin therapy was well-tolerated and resulted in significant glycemic improvement in patients with moderately severe T2DM who were treated for 30 weeks.

Efficacy and safety of sitagliptin monotherapy in Japanese patients with type 2 diabetes.

Efficacy and tolerability of sitagliptin, a dipeptidyl peptidase-4 inhibitor, were assessed in Japanese patients with type 2 diabetes. In a multicenter, double-blind, randomized, placebo-controlled trial in Japan, 151 patients with inadequate glycemic control [HbA(1c) > or =6.5% to <10%, fasting plasma glucose (FPG) > or =126 to < or =240 mg/dL] were randomized to once-daily sitagliptin 100mg or placebo for 12 weeks. After 12 weeks, the least squares (LS) mean change from baseline HbA(1c) was -0.65% (95% CI: -0.80, -0.50) with sitagliptin versus 0.41% (0.26, 0.56) with placebo [between-group difference=-1.05% (-1.27, -0.84); p<0.001]. LS mean change from baseline FPG was -22.5mg/dL (95% CI: -28.0, -17.0) with sitagliptin versus 9.4 mg/dL (3.9, 14.9) with placebo [between-group difference=-31.9 mg/dL (95% CI: -39.7,-24.1); p<0.001]. More patients achieved HbA(1c) <7% or <6.5% with sitagliptin than with placebo (p<0.001). Following a meal tolerance test, 2-h postprandial glucose was significantly reduced with sitagliptin relative to placebo. Clinical and laboratory adverse experiences were similar between treatments, with no reported hypoglycemia adverse events with sitagliptin. Body weight was unchanged relative to baseline in the sitagliptin group (-0.1 kg), but significantly (p<0.01) different relative to the placebo group (-0.7 kg). In this study, once-daily sitagliptin 100mg for 12 weeks improved fasting and postprandial glycemic control and was generally well tolerated in Japanese patients with type 2 diabetes.

Once-daily sitagliptin, a dipeptidyl peptidase-4 inhibitor, for the treatment of patients with type 2 diabetes.

OBJECTIVE: Sitagliptin, an oral, potent, and selective dipeptidyl peptidase-4 (DPP-4) inhibitor was evaluated as once-daily monotherapy in a 12-week randomized, double-blind, placebo-controlled, parallel group, dose-ranging study. Additionally, the glycemic response to sitagliptin 100 mg daily was evaluated as a once-daily (100 mg once-daily) or twice-daily (50 mg twice-daily) dosing regimen. RESEARCH DESIGN AND METHODS: In a multinational, double-blind, randomized, placebo-controlled, parallel-group, dose-range finding study, 555 patients, 23-74 years of age, with HbA(1c) of 6.5-10.0% were randomized to one of five treatment groups: placebo, sitagliptin 25, 50 or 100 mg once-daily, or sitagliptin 50 mg twice-daily for 12 weeks. The efficacy analysis was based on the all-patients-treated population using an ANCOVA model. RESULTS: Mean baseline HbA(1c) ranged from 7.6 to 7.8% across treatment groups, with 29% of all patients with values < or =7%. After 12 weeks, treatment with all doses of sitagliptin significantly (p < 0.05) reduced HbA(1c) by -0.39 to -0.56% and fasting plasma glucose by -11.0 to -17.2 mg/dL relative to placebo, with the greatest reduction observed in the 100-mg once-daily group. Mean daily glucose was significantly (p < 0.05) reduced by -14.0 to -22.6 mg/dL with all doses of sitagliptin relative to placebo. HOMA-beta was significantly (p < 0.05) increased by 11.3-15.2 with all sitagliptin doses relative to placebo. QUICKI and HOMA-IR were not significantly changed with sitagliptin treatment. There were no significant differences observed between the sitagliptin 100 mg once-daily and 50 mg twice-daily groups for any parameter. For sitagliptin, the incidence of adverse events of hypoglycemia was low, with one event in each of the 25- and 50-mg once-daily and 50-mg twice-daily treatment groups and two events in the 100 mg once-daily treatment group. There was no mean change in body weight with sitagliptin relative to placebo. Study duration may be a limitation because the extent of the glycemic response and the safety and tolerability may not have been fully elucidated in this 12-week study. CONCLUSION: Sitagliptin monotherapy improved indices of glycemic control compared to placebo and was generally well-tolerated in patients with type 2 diabetes. The glycemic response to treatment with sitagliptin 100 mg/day was similar between the sitagliptin 100-mg once-daily and 50-mg twice-daily dose regimens.

Glycemic control continues to deteriorate after sulfonylureas are added to metformin among patients with type 2 diabetes.

OBJECTIVE: To describe the course and predictors of glycemic control among patients with type 2 diabetes after sulfonylureas (SUs) are added to metformin (MF). RESEARCH DESIGN AND METHODS: Patients (n = 2,220) treated with MF monotherapy for >90 days before initiating MF plus SU combination therapy between January 1998 and March 2004 were studied in a retrospective analysis of electronic medical records from U.K. primary care practices using the General Practice Research Database. Median glycoslyated hemoglobin A(1c) (A1C) before and after SU initiation was described, and patient characteristics were evaluated as predictors of time until A1C > or =8.0% or glucose-lowering therapy was intensified (by starting insulin or adding a third oral agent). RESULTS: At 6 months post-SU initiation, median A1C resumed deteriorating at a somewhat comparable rate to that observed on MF monotherapy. Higher pre-SU A1C, younger age, female sex, shorter diabetes duration, higher serum creatinine, and being an ex-smoker predicted time until A1C > or =8.0% or glucose-lowering therapy was intensified in various analyses. Median A1C was 9.5% when therapy was intensified. A1C > or =8.0% was estimated to occur in 85% of patients 4 years after SU initiation and in 68% 4 years after initially achieving A1C <7% on MF plus SU therapy. CONCLUSIONS: In this population, glycemic control is improved following the addition of SUs to MF, but deterioration resumes as early as 6 months. The high proportion of patients remaining on MF plus SU therapy despite having A1C > or =8.0% suggests that there are significant barriers to starting insulin or adding a third agent when treatment goals are not achieved with this combination.