Testosterone therapy reduces hepatic steatosis in men with type 2 diabetes and low serum testosterone concentrations

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is highly prevalent in people with diabetes with no available treatment. AIM: To explore the effect of testosterone treatment on liver. Testosterone therapy improves insulin resistance and reduces total body fat, but its impact on the liver remains poorly studied. METHODS: This secondary analysis of a 40 wk, randomised, double-blinded, placebo-controlled trial of intramuscular testosterone undecanoate in men with type 2 diabetes and lowered serum testosterone concentrations evaluated the change in hepatic steatosis as measured by liver fat fraction on magnetic resonance imaging (MRI). RESULTS: Of 88 patients enrolled in the index study, 39 had liver MRIs of whom 20 received testosterone therapy and 19 received placebo. All patients had > 5% hepatic steatosis at baseline and 38 of 39 patients met diagnostic criteria for NAFLD. Median liver fat at baseline was 15.0% (IQR 11.5%-21.1%) in the testosterone and 18.4% (15.0%-28.9%) in the placebo group. Median ALT was 34units/L (26-38) in the testosterone and 32units/L (25-52) in the placebo group. At week 40, patients receiving testosterone had a median reduction in absolute liver fat of 3.5% (IQR 2.9%-6.4%) compared with an increase of 1.2% in the placebo arm (between-group difference 4.7% P < 0.001). After controlling for baseline liver fat, testosterone therapy was associated with a relative reduction in liver fat of 38.3% (95% confidence interval 25.4%-49.0%, P < 0.001). CONCLUSION: Testosterone therapy was associated with a reduction in hepatic steatosis in men with diabetes and low serum testosterone. Future randomised studies of testosterone therapy in men with NAFLD focusing on liver-related endpoints are therefore justified.