Gender-dependent Effects of Metformin on Vaspin and Adiponectin in Type 2 Diabetes Patients: A Randomized Clinical Trial

Abstract

The aim of the study was to assess the effects of metformin on serum concentrations of vaspin and adiponectin in diabetes. Randomized clinical trial of 99 newly diagnosed, medication-naïve, type 2 diabetes patients (NCT01521624) was carried out. Patients were randomly assigned to either metformin 1 000 mg daily plus advice for exercise and lifestyle modification (n=50) or modification alone (n=49). A third group of 50 normoglycemic subjects were also enrolled to compare adipokine concentrations between healthy and diabetes subjects. Serum concentrations of adipokines were measured at baseline and after 12 weeks using ELISA method. Healthy subjects had significantly higher adiponectin levels, but lower concentrations of serum vaspin (p<0.001 in all cases). Vaspin and adiponectin concentrations were 23% and 26% higher in women compared with men. Vaspin dropped significantly after 3-month metformin therapy only in women (1.36 vs. 0.98, p=0.003 in women and 1.31 vs. 1.20, p=0.335 in men). Metformin therapy did not change adiponectin concentration in neither women nor men of the case group (12.66 vs. 12.44 p=0.699 in women and 10.13 vs. 10.94 p=0.253 in men). Comparing case and control groups, metformin decreased vaspin levels more significantly than lifestyle modification in the final multivariate model after controlling for potential confounders only in women (p=0.002) but not men (p=0.896). Conversely, adiponectin levels increased more significantly in the control group, again only in women (p=0.012 and 0.579 for women and men, respectively). Our findings suggest that metformin therapy reduces vaspin concentration in a gender-specific manner. Metformin exerts little benefit in increasing adiponectin levels in diabetes patients.