Effect of testosterone treatment on glucose metabolism in men with type 2 diabetes: A randomized controlled trial

Abstract

OBJECTIVE: To determine whether testosterone therapy improves glucose metabolism in men with type 2 diabetes (T2D) and lowered testosterone. RESEARCH DESIGN AND METHODS: We conducted a randomized, double-blind, parallel, placebo-controlled trial in 88 men with T2D, aged 35-70 years with an HbA 1c ≤8.5% (69 mmol/mol), and a total testosterone level, measured by immunoassay, of ≤12.0 nmol/L (346 ng/dL). Participants were randomly assigned to 40 weeks of intramuscular testosterone undecanoate (n = 45) or matching placebo (n = 43). All study subjects were included in the primary analysis. Seven men assigned to testosterone and six men receiving placebo did not complete the study. Main outcome measures were insulin resistance by homeostatic model assessment (HOMA-IR, primary outcome) and glycemic control by HbA 1c (secondary outcome). RESULTS: Testosterone therapy did not improve insulin resistance (mean adjusted difference [MAD] for HOMA-IR compared with placebo 20.08 [95% CI 20.31 to 0.47; P = 0.23]) or glycemic control (MAD HbA 1c 0.36% [0.0-0.7]; P = 0.05), despite a decrease in fat mass (MAD 22.38 kg [23.10 to 21.66]; P < 0.001) and an increase in lean mass (MAD 2.08 kg [1.52-2.64]; P < 0.001). Testosterone therapy reduced subcutaneous (MAD 2320 cm 3 [2477 to 2163]; P < 0.001) but not visceral abdominal adipose tissue (MAD 140 cm 3 [289 to 369]; P = 0.90). CONCLUSIONS: Testosterone therapy does not improve glucose metabolism or visceral adiposity in obese men with moderately controlled T2D and modest reductions in circulating testosterone levels typical for men with T2D. © 2014 by the American Diabetes Association.