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 HbA1c ≤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 HbA1c (secondary outcome).
Results: Testosterone therapy did not improve insulin resistance (mean adjusted difference [MAD] for HOMA-IR compared with placebo -0.08 [95% CI -0.31 to 0.47; P = 0.23]) or glycemic control (MAD HbA1c 0.36% [0.0-0.7]; P = 0.05), despite a decrease in fat mass (MAD -2.38 kg [-3.10 to -1.66]; 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 -320 cm(3) [-477 to -163]; P < 0.001) but not visceral abdominal adipose tissue (MAD 140 cm(3) [-89 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. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.