Differential Effects of Thiazolidinediones and Dipeptidyl Peptidase-4 Inhibitors on Insulin Resistance and -Cell Function in Type 2 Diabetes Mellitus: A Propensity Score-Matched Analysis

IntroductionComparisons of the glycemic durability between thiazolidinediones (TZDs) and dipeptidyl peptidase-4 (DPP-4) inhibitors remain insufficient. This study aimed to find clues for the differences in glycemic durability between TZDs and DPP-4 inhibitors by comparing the insulin resistance and -cell function among patients using these agents.MethodsA total of 241 patients with type 2 diabetes mellitus (T2DM) treated with either pioglitazone (a TZD) or DPP-4 inhibitors as combination therapy with metformin for at least 1year were analyzed. A propensity score based on the patients' baseline characteristics and glycated hemoglobin (HbA1c) was used to match them. Indices for insulin resistance and secretory function of -cells, namely the homeostasis model assessment of insulin resistance (HOMA-IR) or -cells (HOMA-), were calculated and compared. Multiple regression analysis was performed to find the independent variables correlated with -cell function or insulin resistance.ResultsEvaluation of the data from 168 matched patients with T2DM showed that TZD users had significantly better insulin sensitivity compared with DPP-4 inhibitor users (HOMA-IR 2.31.9 vs. 3.5 +/- 3.2, p=0.003). Conversely, DPP-4 inhibitor users secreted more insulin than TZD users (HOMA- 45.7 +/- 31.6 vs. 61.4 +/- 49.5, p=0.016). Multiple linear regression analysis showed that these agents were independently associated with both insulin resistance and -cell function.Conclusion p id=Par4 TZD users showed significantly better insulin sensitivity, whereas DPP-4 inhibitor users secreted more insulin from -cells under similar glycemic control.