Real-world data from an ongoing international audit on testosterone deficiency in men with type 2 diabetes, presented at this year’s Annual Meeting of The European Association for the Study of Diabetes (EASD) in Hamburg (2-6 Oct), suggests that testosterone replacement therapy (TRT) improves glycaemic control for up to 2 years.
The preliminary data from 37 centres across 8 countries participating in the Association of British Clinical Diabetologists (ABCD) audit indicate that the continued decrease in HbA1c (a measure of average blood sugar levels over the past 2-3 months) over time is likely due to the ongoing effects of testosterone on insulin resistance and fat reduction.
These results offer initial insights into whether TRT could benefit diabetes and obesity.
Two decades ago, researchers discovered a link between low testosterone in men and the prevalence of type 2 diabetes, with estimates suggesting that around 40% of men with type 2 diabetes have symptomatic testosterone deficiency. This deficiency is linked to adverse effects on cardiovascular risk factors, osteoporosis, psychological wellbeing, and is associated with double the risk of death in men with type 2 diabetes.
Multiple studies have shown that TRT could benefit men with hypogonadism (testosterone deficiency) who also have type 2 diabetes, obesity, and other cardiometabolic disorders. TRT has been shown to reduce insulin resistance, HbA1c, cholesterol, obesity, mortality, and improve quality of life and sexual function.
However, the uptake of TRT has been slow, partly due to conflicting findings on cardiovascular risks. A recently published large, multicentre randomised trial on the cardiovascular safety of TRT found no difference in major cardiovascular events between testosterone and placebo-treated groups.
“Despite this evidence, the use of testosterone among endocrinologists remains low, and many diabetologists are unaware of the association between testosterone and diabetes,” says Professor Hugh Jones from Barnsley Hospital in the UK, who led the study.
“We hope that the ABCD audit will provide enough real-world clinical practice data to determine which patients respond in terms of quality of life, symptoms, and cardiometabolic benefits.”
The ABCD audit allows anonymised data input from new and retrospective patients who have commenced on TRT and those with testosterone deficiency who are not treated. The audit aims to determine the real-world benefits and safety of TRT on symptoms, glycaemic control, obesity, other cardiometabolic parameters (e.g., lipids, blood pressure, BMI, and waist circumference), and on cardiovascular events and diabetes complications.
So far, 34 centres in 8 countries (the UK, Germany, Canada, New Zealand, South Africa, Malaysia, and Vietnam) including 428 patients (average age 71 years) have joined the audit.
The testosterone formulations used by these patients are gels and long-acting testosterone undeconoate intramuscular injections. Guidelines state that after initiation of TRT, patients should be reviewed at 3, 6, 12 months, and then yearly.
The researchers evaluated HbA1c on paired data after 3, 12, and 24 months on patients treated with TRT. The recommended range for most people with diabetes is to keep HbA1c under 48 mmol/mol.
After 3 months of TRT, average HbA1c fell by 4.9 mmol/mol from 71 mmol/mol to 66 mmol/mol (81 patients); after 12 months, it fell by 9.6 mmol/mol from 71 mmol/mol to 61.7 mmol/mol (121 patients); and after 24 months, it declined by 15.4 mmol/mol from 71.2 mmol/mol to 55 mmol/mol (101 patients).
“More and longer-term data from a larger number of patients included in the audit are needed to determine which type of patient is likely to respond to testosterone therapy,” says Professor Jones. “These findings will also form the evidence basis for general practitioners and endocrinologists to proactively ask patients with type 2 diabetes about their symptoms, investigate, and diagnose testosterone deficiency appropriately, and treat them with testosterone where indicated.”
