Switching from Sitagliptin to Alogliptin under Treatment with Pioglitazone Increases High Molecular Weight Adiponectin in Type 2 Diabetes: A Prospective Observational Study

Background: There are few clinical trials addressing the difference in pleiotropic effects among dipeptidyl peptidase (DPP)-4 inhibitors. We aimed to identify difference in effects on biochemical markers of inflammation, oxidative stress, and atherosclerosis between two DPP-4 inhibitors in patients with type 2 diabetes. Methods: We prospectively observed twenty subjects with type 2 diabetes before and after a practical medication change from a treatment with pioglitazone and sitagliptin 50 mg to a combination tablet containing the same dose of pioglitazone and alogliptin 25mg, which was actually identical to switching from sitagliptin to alogliptin. After 3 months, changes from baseline in clinical data and various biochemical markers were evaluated. In particular, body mass index (BMI) and hemoglobin A1c (HbA1c) were additionally followed after 12 months for evaluation of chronic outcomes. Results: Among markers, serum levels of high molecular weight (HMW) adiponectin significantly increased from 6.9 ± 3.6 μg/ml to 8.2 ± 4.0 μg/ml (P = 0.0045). Although no clinical data changed after 3 months, significant improvements in HbA1c and BMI were observed after 12 months. Their rates of changes tended to inversely correlate with the increased percentages of serum HMW adiponectin levels during initial 3 months, but they did not reach statistical significance. Conclusions: In spite of pretreatment with pioglitazone, additional increase in serum HMW adiponectin levels was demonstrated after switching from sitagliptin to alogliptin. Given multiple favorable roles of adiponectin in metabolic and cardiovascular states, alogliptin, at least when combined with pioglitazone, would be beneficial in treatment of type 2 diabetes.