Abstract
AIMS/INTRODUCTION: Recently, dipeptidyl peptidase-4 (DPP-4) inhibitors have become available in Japan. It has not yet been clarified what clinical parameters could discriminate DPP-4 inhibitor-effective patients from DPP-4 inhibitor-ineffective patients. MATERIALS AND METHODS: We reviewed 33 consecutive patients with type 2 diabetes admitted to Osaka University Hospital for glycemic control. All of the patients were treated with medical nutrition therapy plus insulin therapy to improve fasting plasma glucose (FPG) and postprandial glucose below 150 and 200 mg/dL, respectively. After insulin secretion and insulin resistance were evaluated, insulin was replaced by DPP-4 inhibitors. The efficacy of DPP-4 inhibitors was determined according to whether glycemic control was maintained at the target levels. RESULTS: Dipeptidyl peptidase-4 inhibitors were effective in 16 of 33 patients. DPP-4 inhibitor-effective patients were younger than DPP-4 inhibitor-ineffective patients. Body mass index (BMI) was significantly higher in DPP-4 inhibitor-effective patients. Endogeneous insulin-secreting capacity, including insulinogenic index (II), fasting plasma C-peptide (F-CPR) and C-peptide index (CPI), was more sustained in DPP-4 inhibitor-effective patients than DPP-4 inhibitor-ineffective patients. Insulin resistance evaluated by homeostasis model assessment of insulin resistance (HOMA-IR) was significantly higher in DPP-4 inhibitor-effective patients than DPP-4 inhibitor-ineffective patients. In receiver operating characteristic analyses, the cut-off values for predicting the efficacy of DPP-4 inhibitors were 0.07 for II, 1.5 ng/mL for F-CPR, 1.0 for CPI, 23.0 kg/m(2) for BMI, 1.3 for HOMA-IR and 67.5 years for age. CONCLUSIONS: Dipeptidyl peptidase-4 inhibitors were effective in Japanese type 2 diabetic patients with sustained endogenous insulin-secreting capacity, a higher BMI and insulin resistance.