Safety and Efficacy of Sitagliptin Added to Insulin Therapy for Type 2 Diabetes

Inclusion Criteria: * outpatients with type 2 diabetes * addition of sitagliptin to insulin therapy * aged 20 years or older * HbA1c of 6.9% or higher (NGSP) at the time of adding sitagliptin Exclusion Criteria: * history of hypersensitivity to sitagliptin * severe ketosis, diabetic coma, and/or precoma within 6 months before sitagliptin administration * sever infection and/or severe trauma, and/or patients who are scheduled to undergo / have recently underwent surgery * severe renal dysfunction (serum creatinine \[mg/dL\]: 2.5 or higher for men; 2.0 or higher for women) * ongoing treatment with glinide(s) * judgment as ineligible for the study by the attending physician