Increased Free Testosterone Levels in Men with Uncontrolled Type 2 Diabetes Five Years After Randomization to Bariatric Surgery

Hypogonadism frequently occurs in male patients with type 2 diabetes (T2DM) and is linked to insulin resistance and inflammation. Testosterone levels rise acutely in obese patients following bariatric surgery, though long-term changes have not been investigated in a randomized controlled trial. This study evaluated obese men with T2DM randomized to either bariatric surgery or medical therapy. Testosterone, gonadotropins, body composition, insulin sensitivity, and inflammatory markers were evaluated in 32 patients at baseline and at 5 years. Surgical patients had 47.4% increase in free testosterone compared to medical therapy patients who had 2.2% decrease (P = 0.013). Increase in free testosterone correlated with reduction in body weight, high-sensitivity C-reactive protein (hsCRP), and leptin levels. Prolonged improvements in testosterone levels after bariatric surgery in T2DM are found to be related to reduction in body weight and adipogenic inflammation.