Impact of dipeptidyl peptidase-4 inhibitors on serum adiponectin: a meta-analysis

Background: Adiponectin, an adipose-specific protein, is negatively correlated with pro-atherogenic low-density lipoprotein cholesterol (LDL-C) and other cardiovascular risk factors such as insulin resistance. Therefore, low levels of adiponectin are associated with a higher risk for diabetes and cardiovascular disease. Dipeptidyl peptidase-4 inhibitors (DPP4i) have been used for the treatment of type 2 diabetes mellitus (T2DM) as reversible inhibitors through interacting with DPP4 substrate and increase serum incretins such as glucagon-like peptide-1 (GLP-1). The present study aimed to evaluate the effect of DPP4i on serum adiponectin in T2DM patients. Methods: The PubMed, Embase, and Cochrane library databases were searched from inception to February 2016. Randomized controlled trials, evaluating the DPP4i (sitagliptin and vildagliptin) versus comparator (placebo or active-comparison), in T2DM patients with duration of >= 12 weeks, were identified. Weighted differences in means of adiponectin levels were calculated by using a fixed or random-effects model. Results: Ten randomized controlled trials, including 1,495 subjects, were identified. Compared with placebo, DPP4i (sitagliptin and vildagliptin) treatment significantly elevated adiponectin levels by 0.74 mu g/mL (95% confidence interval [CI], 0.45 to 1.03) relative to that using an active-comparison by 0.00 mu g/mL (95% CI, - 0.57 to 0.56). Compared with active- comparison, vildagliptin treatment increased adiponectin levels by 0.32 mu g/mL (95% CI, - 0.01 to 0.65), whereas sitagliptin treatment decreased adiponectin levels by - 0.24 mu g/mL (95% CI, - 1.07 to 0.58). Trials examining effects of other DPP4i were not found. Conclusions: Sitagliptin and vildagliptin increased serum adiponectin levels and had no stronger effect than traditional oral antidiabetic drugs. Further trials with larger sample size are needed to confirm the results and investigate the association between serum adiponectin levels and treatment of other DPP-4 inhibitors.