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.

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.

Rfm1, a novel tethering factor required to recruit the Hst1 histone deacetylase for repression of middle sporulation genes.

Transcriptional repression is often correlated with the alteration of chromatin structure through modifications of the nucleosomes in the promoter region, such as by deacetylation of the N-terminal histone tails. This is presumed to make the promoter region inaccessible to other regulatory factors and the general transcription machinery. To accomplish this, histone deacetylases are recruited to specific promoters via DNA-binding proteins and tethering factors. We have previously reported the requirement for the NAD(+)-dependent histone deacetylase Hst1 and the DNA-binding protein Sum1 for vegetative repression of many middle sporulation genes in Saccharomyces cerevisiae. Here we report the identification of a novel tethering factor, Rfm1, that is required for Hst1-mediated repression. Rfm1 interacts with both Sum1 and Hst1 and is required for the Sum1-Hst1 interaction. DNA microarray and Northern blot analyses showed that Rfm1 is required for repression of the same subset of Sum1-repressed genes that require Hst1. These results suggest that Rfm1 is a specificity factor that targets the Hst1 deacetylase to a subset of Sum1-regulated genes.