Recent studies reveal complex and mixed results on testosterone therapy’s role in managing or preventing type 2 diabetes in men, highlighting the need for clearer guidance amid ongoing debate.
Research suggests testosterone may do more than support libido or muscle mass in men with type 2 diabetes, but its effect on blood sugar is narrower than some advocates imply. In one large Australian trial, testosterone was added to a lifestyle programme for overweight men with low hormone levels and worsening glucose control. After 2 years, men given the hormone were less likely to progress to diabetes than those on placebo, according to the trial results reported in later analyses. The study has been widely cited because it was large, randomised and placebo-controlled, but it tested testosterone alongside diet and exercise rather than as a stand-alone treatment.
That distinction matters. A separate 40-week trial in men who already had type 2 diabetes and low testosterone found a very different result. Published in 2014 and indexed by PubMed, the study reported that testosterone undecanoate did not significantly improve glucose metabolism versus placebo, even though it changed body composition. Men on testosterone lost fat and gained lean mass, but their blood sugar control did not meaningfully improve. A related trial in 2019 reached a similar conclusion, finding no significant benefit for glycaemic control or endothelial function in men with newly diagnosed functional hypogonadism and diabetes.
The mixed results help explain why testosterone has remained a disputed tool in diabetes care. In men with low testosterone, treatment may improve sexual symptoms, energy and body composition, and one randomised trial in 2014 found better sexual function and less fatigue. But the hormone does not appear to be a reliable substitute for glucose-lowering treatment. What it may do, according to the Australian data, is reduce the chances of crossing into diabetes in men who are already at high risk and are also following a structured lifestyle programme.
Recent genetic research has added another layer to the debate. A 2020 analysis from Exeter and Cambridge, using UK Biobank data, found that men with genetic variants linked to higher testosterone had lower odds of type 2 diabetes, while the same variants were associated with higher diabetes risk in women. Mathis Grossmann, who has reviewed the field in 2024, says the evidence remains complex and that more research is needed to clarify who, if anyone, should be treated for diabetes risk with testosterone rather than standard metabolic therapy.
Disclaimer: This content is for informational purposes only and is not intended to be a substitute for professional medical judgment, advice, diagnosis, or treatment.
