• Dipeptidyl peptidase-4 inhibitor;
  • Incretins;
  • Sitagliptin


Aims/Introduction:  Patients with type 2 diabetes mellitus often require treatment with more than one oral antihyperglycemic agent to achieve their glycemic goal. The present study was carried out to assess the efficacy and safety of sitagliptin as add-on therapy in Japanese patients with type 2 diabetes mellitus inadequately controlled (HbA1c ≥ 6.9% and <10.4%) on pioglitazone monotherapy (15–45 mg/day).

Materials and Methods:  In the initial 12-week, double-blind treatment period, patients were randomized (1:1) to sitagliptin 50 mg/day (n = 66) or placebo (n = 68), followed by a 40-week open-label treatment period in which all patients received sitagliptin 50 mg/day that could have been increased to 100 mg/day for patients meeting predefined glycemic parameters.

Results:  After 12 weeks, mean changes from baseline in HbA1c (the primary end-point), fasting plasma glucose and 2-h post-meal glucose were −0.8%, −0.9 mmol/L and −2.7 mmol/L, respectively, in the sitagliptin group compared with placebo (all < 0.001). The incidence of adverse experiences during the double-blind treatment period was similar in both treatment groups, and the incidences of hypoglycemia and gastrointestinal adverse experiences were low. In the open-label period, improvements in glycemic parameters with sitagliptin treatment were maintained and sitagliptin was generally well tolerated.

Conclusions:  Sitagliptin as add-on therapy provided significant improvements in glycemic parameters and was well tolerated in Japanese patients with type 2 diabetes mellitus inadequately controlled on pioglitazone monotherapy. This trial was registered with (no. NCT00372060). (J Diabetes Invest, doi: 10.1111/j.2040-1124.2011.00120.x, 2011)