Long-Term Testosterone Therapy in Type 2 Diabetes Is Associated with Decreasing Waist Circumference and Improving...

To describe the 4-year metabolic follow-up results from the BLAST study.

Baseline hemoglobin A1c (HbA1c), weight, and waist circumference (WC) data were recorded in 185 men recruited for the BLAST randomised controlled trial (RCT) and erectile function (EF) scores were also available in an additional 48 men screened for the RCT. Intra/inter-group associations between these parameters and testosterone replacement therapy (TRT) were assessed at 1) end of the RCT (30 weeks), 2) open-label phase (82 weeks), and 3) final assessment via non-parametric statistics.

Improvement in HbA1c and weight at the end of the RCT and open-label phase in men on TRT was not maintained long-term. The convergence in HbA1c could have been due to incentivised care with HbA1c targets. Interestingly those on TRT at final assessment required fewer anti-diabetic agents. The weight increase in routine care may have been due to changes in diabetes medication or an increase in lean muscle mass. WC continued to decrease in men on TRT indicating possible reduction in visceral fat. Improvement in EF scores continued with long-term TRT, this was abolished when TRT was discontinued.

This study hints at benefits in glycaemic control, weight and WC, and long-term RCTs studying mechanisms of benefit and clinical outcomes are necessary. Our results also show that EF scores continued to improve with long-term TRT, even beyond the 6 months that we previously reported in the BLAST RCT.