Effect of Januvia on Beta Cell Function in Patients With Diabetes Mellitus

The study is designed to investigate the effect of 18 weeks treatment with Sitagliptin 100 mg/day on the insulin secretion capacity of beta cells. Patients who meet the study enrollment criteria will undergo 2 experiments (see description below); a graded hyperglycemic technique and a meal test, prior to randomization and after a 12-wk double-blind study period. The treatment effect will shed light on the magnitude of the beta cell capacity to increase its mass and function.