Background— The glucagon-like peptide 1 receptor (GLP-1R) is believed to mediate glucoregulatory and cardiovascular effects of the incretin hormone GLP-1(7-36) (GLP-1), which is rapidly degraded by dipeptidyl peptidase-4 (DPP-4) to GLP-1(9-36), a truncated metabolite generally thought to be inactive. Novel drugs for the treatment of diabetes include analogues of GLP-1 and inhibitors of DPP-4; however, the cardiovascular effects of distinct GLP-1 peptides have received limited attention. Methods and Results— Here, we show that endothelium and cardiac and vascular myocytes express a functional GLP-1R as GLP-1 administration increased glucose uptake, cAMP and cGMP release, left ventricular developed pressure, and coronary flow in isolated mouse hearts. GLP-1 also increased functional recovery and cardiomyocyte viability after ischemia-reperfusion injury of isolated hearts and dilated preconstricted arteries from wild-type mice. Unexpectedly, many of these actions of GLP-1 were preserved in Glp1r−/− mice. Fur...

Cardioprotective and Vasodilatory Actions of Glucagon-Like Peptide 1 Receptor Are Mediated Through Both Glucagon-Like Peptide 1 Receptor–Dependent and –Independent Pathways

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 HbA1c [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 ≥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 ≥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 β-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 β-cell function, and was well tolerated in patients with type 2 diabetes.

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Effect of the Dipeptidyl Peptidase-4 Inhibitor Sitagliptin as Monotherapy on Glycemic Control in Patients With Type 2 Diabetes

OBJECTIVE —The efficacy and safety of the dipeptidyl peptidase-4 inhibitor, sitagliptin, added to ongoing metformin therapy, were assessed in patients with type 2 diabetes who had inadequate glycemic control (HbA 1c [A1C] ≥7 and ≤10%) with metformin alone. RESEARCH DESIGN AND METHODS —After a screening diet/exercise run-in period, a metformin dose titration/stabilization period, and a 2-week, single-blind, placebo run-in period, 701 patients, aged 19–78 years, with mild to moderate hyperglycemia (mean A1C 8.0%) receiving ongoing metformin (≥1,500 mg/day) were randomly assigned to receive the addition of placebo or sitagliptin 100 mg once-daily in a 1:2 ratio for 24 weeks. Patients exceeding specific glycemic limits were provided rescue therapy (pioglitazone) until the end of the study. The efficacy analyses were based on an all-patients-treated population using an ANCOVA and excluded data obtained after glycemic rescue. RESULTS —At week 24, sitagliptin treatment led to significant reductions compared with placebo in A1C (−0.65%), fasting plasma glucose, and 2-h postmeal glucose. Fasting insulin, fasting C-peptide, fasting proinsulin-to-insulin ratio, postmeal insulin and C-peptide areas under the curve (AUCs), postmeal insulin AUC–to–glucose AUC ratio, homeostasis model assessment of β-cell function, and quantitative insulin sensitivity check index were significantly improved with sitagliptin relative to placebo. A significantly greater proportion of patients achieved an A1C CONCLUSIONS —Sitagliptin 100 mg once-daily added to ongoing metformin therapy was efficacious and well tolerated in patients with type 2 diabetes who had inadequate glycemic control with metformin alone.

https://care.diabetesjournals.org/content/diacare/29/12/2638.full.pdf

Efficacy and Safety of the Dipeptidyl Peptidase-4 Inhibitor Sitagliptin Added to Ongoing Metformin Therapy in Patients With Type 2 Diabetes Inadequately Controlled With Metformin Alone

Aim: To compare the efficacy and safety of sitagliptin vs glipizide in patients with type 2 diabetes and inadequate glycaemic control [haemoglobin A1c (HbA1c) ≥ 65 and ≤10%] on metformin monotherapy

Methods:  After a metformin dose titration/stabilization period (≥1500 mg/day), 1172 patients were randomized to the addition of sitagliptin 100 mg qd (N = 588) or glipizide 5 mg/day (uptitrated to a potential maximum 20 mg/day) (N = 584) for 52 weeks The primary analysis assessed whether sitagliptin was non-inferior to glipizide regarding HbA1c changes from baseline at Week 52 using a per-protocol approach

Results:  From a mean baseline of 75%, HbA1c changes from baseline were −067% at Week 52 in both groups, confirming non-inferiority The proportions achieving an HbA1c < 7% were 63% (sitagliptin) and 59% (glipizide) Fasting plasma glucose changes from baseline were −056 mmol/l (−100 mg/dl) and −042 mmol/l (−75 mg/dl) for sitagliptin and glipizide, respectively The proportion of patients experiencing hypoglycaemia episodes was significantly (p < 0001) higher with glipizide (32%) than with sitagliptin (5%), with 657 events in glipizide-treated patients compared with 50 events in sitagliptin-treated patients Sitagliptin led to weight loss (change from baseline =−15 kg) compared with weight gain (+11 kg) with glipizide [between-treatment difference (95% confidence interval) =−25 kg (−31, −20); p < 0001]

Conclusions:  In this study, the addition of sitagliptin compared with glipizide provided similar HbA1c-lowering efficacy over 52 weeks in patients on ongoing metformin therapy Sitagliptin was generally well tolerated, with a lower risk of hypoglycaemia relative to glipizide and with weight loss compared with weight gain with glipizide

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1463-1326.2006.00704.x

Efficacy and safety of the dipeptidyl peptidase‐4 inhibitor, sitagliptin, compared with the sulfonylurea, glipizide, in patients with type 2 diabetes inadequately controlled on metformin alone: a randomized, double‐blind, non‐inferiority trial

Aim: To assess the efficacy and safety of a 24-week treatment with sitagliptin, a highly selective once-daily oral dipeptidyl peptidase-4 (DPP-4) inhibitor, in patients with type 2 diabetes who had inadequate glycaemic control [glycosylated haemoglobin (HbA1c) ≥7.5% and ≤10.5%] while on glimepiride alone or in combination with metformin.

Methods:  After a screening, diet/exercise run-in and drug wash-off period, a glimepiride ± metformin dose titration/stabilization period and a 2-week, single-blind placebo run-in, 441 patients (of ages 18–75 years) were randomized to receive the addition of sitagliptin 100 mg once daily or placebo in a 1 : 1 ratio for 24 weeks. Of these patients, 212 were on glimepiride (≥4 mg/day) monotherapy and 229 were on glimepiride (≥4 mg/day) plus metformin (≥1500 mg/day) combination therapy. Patients exceeding pre-specified glycaemic thresholds during the double-blind treatment period were provided open-label rescue therapy (pioglitazone) until study end. The primary efficacy analysis evaluated the change in HbA1c from baseline to Week 24. Secondary efficacy endpoints included fasting plasma glucose (FPG), 2-h post-meal glucose and lipid measurements.

Results:  Mean baseline HbA1c was 8.34% in the sitagliptin and placebo groups. After 24 weeks, sitagliptin reduced HbA1c by 0.74% (p < 0.001) relative to placebo. In the subset of patients on glimepiride plus metformin, sitagliptin reduced HbA1c by 0.89% relative to placebo, compared with a reduction of 0.57% in the subset of patients on glimepiride alone. The addition of sitagliptin reduced FPG by 20.1 mg/dl (p < 0.001) and increased homeostasis model assessment-β, a marker of β-cell function, by 12% (p < 0.05) relative to placebo. In patients who underwent a meal tolerance test (n = 134), sitagliptin decreased 2-h post-prandial glucose (PPG) by 36.1 mg/dl (p < 0.001) relative to placebo. The addition of sitagliptin was generally well tolerated, although there was a higher incidence of overall (60 vs. 47%) and drug-related adverse experiences (AEs) (15 vs. 7%) in the sitagliptin group than in the placebo group. This was largely because of a higher incidence of hypoglycaemia AEs (12 vs. 2%, respectively) in the sitagliptin group compared with the placebo group. Body weight modestly increased with sitagliptin relative to placebo (+0.8 vs. −0.4 kg; p < 0.001).

Conclusions:  Sitagliptin 100 mg once daily significantly improved glycaemic control and β-cell function in patients with type 2 diabetes who had inadequate glycaemic control with glimepiride or glimepiride plus metformin therapy. The addition of sitagliptin was generally well tolerated, with a modest increase in hypoglycaemia and body weight, consistent with glimepiride therapy and the observed degree of glycaemic improvement.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1463-1326.2007.00744.x

Efficacy and safety of the dipeptidyl peptidase-4 inhibitor, sitagliptin, in patients with type 2 diabetes mellitus inadequately controlled on glimepiride alone or on glimepiride and metformin.

Context: In response to a meal, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP) are released and modulate glycemic control Normally these incretins are rapidly degraded by dipeptidyl peptidase-4 (DPP-4) DPP-4 inhibitors are a novel class of oral antihyperglycemic agents in development for the treatment of type 2 diabetes The degree of DPP-4 inhibition and the level of active incretin augmentation required for glucose lowering efficacy after an oral glucose tolerance test (OGTT) were evaluated Objective: The objective of the study was to examine the pharmacodynamics, pharmacokinetics, and tolerability of sitagliptin Design: This was a randomized, double-blind, placebo-controlled, three-period, single-dose crossover study Setting: The study was conducted at six investigational sites Patients: The study population consisted of 58 patients with type 2 diabetes who were not on antihyperglycemic agents Interventions: Interventions included sitagliptin 25 mg, sitaglipti

Effect of Single Oral Doses of Sitagliptin, a Dipeptidyl Peptidase-4 Inhibitor, on Incretin and Plasma Glucose Levels after an Oral Glucose Tolerance Test in Patients with Type 2 Diabetes

Bruno Dietrich

Papers

Effect of Single Oral Doses of Sitagliptin, a Dipeptidyl Peptidase-4 Inhibitor, on Incretin and Plasma Glucose Levels after an Oral Glucose Tolerance Test in Patients with Type 2 Diabetes