Pioglitazone increases serum DPP-4 level in type 2 diabetes mellitus

Objective: The aim of this study is to clarify the effect of pioglitazone on serum Dipeptidyl peptidase-4 (DPP-4) level in type 2 diabetes mellitus.

Methods: Chronological changes in serum DPP-4 level were observed in 22 patients treated with pioglitazone and 15 with metformin during 12 months. Serum DPP-4 concentrations were measured by an ELISA kit. Results: In the pioglitazone group, serum DPP-4 levels were significantly increased from baseline (774 ± 198 ng/mL) with mean changes of 53 mg/mL [6.8% increase, 95% confidence interval (CI) 2 to 104, p<0.05] after 3 months and of 74 mg/mL (9.4% increase, 95% CI 21 to 126, p<0.01) after 12 months. On the other hand, serum DPP-4 levels were not changed in the metformin group. Percent change in serum DPP-4 level was significantly and positively correlated with percent change in body mass index (r=0.39, p<0.02). The association was still significant even after adjusting for age, duration of diabetes, serum creatinine, and HbAc1 (β=0.59, p<0.02).

Conclusion: The present study showed that pioglitazone, but not metformin, chronologically increased serum DPP-4 levels during 12 months.