Effect of metformin on free testosterone level in male diabetic patients: A comparative study

When we consider the treatment of polycystic ovary syndrome (PCOS), one of our treatment options is metformin, which reduces free testosterone levels in PCOS patients. We were interested to know what happens to the free testosterone levels of male type 2 diabetes mellitus (T2DM) patients when we use metformin. The effect of metformin on testosterone level, fertility, and sexual activity in males has been issues of interest to researchers. This study was conducted to observe the effect of metformin on free testosterone levels in male T2DM patients. One hundred fifty male patients (mean age, 40-46 years; SD, 1.2), newly diagnosed with T2DM and drug-naïve, were enrolled. Initially, the baseline-free testosterone level was measured. Then, 75 of them were given metformin, and 75 of them were treated with other antidiabetics. After treatment for 30 days, the free testosterone level was measured again. In both groups, the mean value of free testosterone change in 1 month was calculated. Then, a comparison between the mean change in the 2 groups was done. Baseline-free testosterone of metformin (mean = 7.9, SD = 2.2) and non-metformin (mean = 8.1, SD = 1.9) groups were compared, and no significant difference was seen between them (P = .264). After 30 days of treatment, there was an increased level of free testosterone in both groups (mean metformin = 9.75, non-metformin = 10.77). But. free testosterone rise in non-metformin group(M = 2.63,SD = 1.07) was significantly higher (mean difference = .80,95% CI) than metformin group (M = 1.82,SD = .99,t = 4.76, P < .001). Metformin is inferior to other antidiabetic medications in raising free testosterone levels. Larger multicenter studies are further warranted.