The Effect of Metformin and Metformin-Testosterone Combination on Cardiometabolic Risk Factors in Men with Late-onset Hypogonadism and Impaired Glucose Tolerance.

Abstract

No previous study has investigated the effect of metformin, administered alone or together with testosterone, on cardiometabolic risk factors in men with hypogonadism. The study included 30 men with late-onset hypogonadism (LOH) and impaired glucose tolerance (IGT) who had been complying with lifestyle intervention. After 12 weeks of metformin treatment (1.7 g daily), the participants were allocated to one of 2 groups treated for the following 12 weeks with oral testosterone undecanoate (120 mg daily, n=15) or not receiving androgen therapy (n=15). Plasma lipids, glucose homeostasis markers, as well as plasma levels of androgens, uric acid, high-sensitivity C-reactive protein (hsCRP), homocysteine and fibrinogen were determined before and after 12 and 24 weeks of therapy with the final dose of metformin. Patients with LOH and IGT had higher levels of hsCRP, homocysteine and fibrinogen than subjects with only LOH (n=12) or only IGT (n=15). Metformin administered alone improved insulin sensitivity, as well as reduced 2-h postchallenge plasma glucose and triglycerides. Testosterone-metformin combination therapy decreased also total and LDL cholesterol, uric acid, hsCRP, homocysteine and fibrinogen, as well as increased plasma testosterone. The effect of this combination therapy on testosterone, insulin sensitivity, hsCRP, homocysteine and fibrinogen was stronger than that of metformin alone. The obtained results indicate that IGT men with LOH receiving metformin may gain extra benefits if they are concomitantly treated with oral testosterone.