Testosterone Therapy to Prevent Type 2 Diabetes Mellitus in At-Risk Men (T4DM): Design and Implementation of a Double-Blind Randomized Controlled Trial

Diabetes Obes Metab. 2019 Apr;21(4):772-780. doi: 10.1111/dom.13601. Epub 2019 Jan 4.


Background: Low circulating testosterone is associated with an increased risk of developing type 2 diabetes (T2DM) in overweight men with impaired glucose tolerance (IGT).

Aims: To determine in a multi-centre, double-blinded placebo-controlled randomized trial whether testosterone treatment combined with lifestyle intervention (Weight Watchers) relative to lifestyle intervention alone reduces T2DM incidence and improves glucose tolerance at 2 years.

Study population: Overweight or obese men aged 50-74 years with a serum testosterone of ≤14 nmol/L and IGT or newly diagnosed T2DM established by an oral glucose tolerance test (OGTT).

Setting, drug and protocol: Six Australian capital city-based tertiary care centres. Participants were randomized 1:1 and injected with testosterone undecanoate (1000 mg/4 mL) or vehicle (4 mL castor oil), at baseline, 6 weeks and 3-monthly thereafter. PRIMARY ENDPOINTS: (a) Proportion of participants with 2-hour OGTT ≥11.1 mmol/L at 2 years, and (b) a difference at 2 years ≥0.6 mmol/L in the mean 2-hour OGTT glucose between treatments.

Secondary endpoints: Fasting insulin, HbA1c, body composition, maximal handgrip strength; sexual function and lower urinary tract symptoms; serum sex steroids and sex hormone binding globulin; mood and psychosocial function; adherence to lifestyle intervention; and healthcare utilization and costs.

Safety: Overseen by an Independent Data Safety Monitoring Committee. Haematocrit, lipids and prostate-specific antigen (PSA) are assessed 6-monthly and information relating to haematological, urological and cardiovascular adverse events from each clinic visit. SUB-STUDIES: (a) Changes in bone density and micro-architecture, (b) motivation and behaviour, (c) telomere length, (d) extended treatment up to 4 years, and (e) hypothalamo-pituitary testicular axis recovery at treatment end.

Keywords: body composition; cardiovascular; motivation; obesity; prevention; testosterone; type 2 diabetes mellitus.

Publication types

  • Research Support, Non-U.S. Gov't