medwireNews: A randomized trial indicates that testosterone treatment among men with prediabetes or newly diagnosed type 2 diabetes significantly reduces the risk for them having type 2 diabetes 2 years later.
Nevertheless, the researchers say: “We consider it premature to advocate for the widespread use of testosterone for diabetes prevention in men without pathological hypogonadism.”
Despite the efficacy shown here, factors such as cardiovascular safety remain to be established, caution Gary Wittert (South Australian Health and Medical Research Institute, Adelaide) and study co-authors.
The 1007 Testosterone for Diabetes Mellitus (T4DM) trial participants had a waist circumference of at least 95 cm, with impaired glucose tolerance (80% of men) or newly diagnosed type 2 diabetes (20%), and a testosterone level of 14 nmol/L or less but without pathological hypogonadism.
During 2 years of follow-up, around 75% of the testosterone and placebo groups continued to take their randomly assigned medication, which they received in addition to a community-based lifestyle program.
By the end of this period, confirmed diabetes, defined as 2-hour glucose of 11.1 mmol/L (200 mg/dL) or higher, was present in 12% of the testosterone group versus 21% of the placebo group, which was a significant difference.
The effect was consistent for those defined as having diabetes and impaired glucose tolerance at baseline, and for those with testosterone levels of at least 11 nmol/L, or with lower levels.
“So far, so good, and on the surface, the results align with preceding biological and emerging genetic research,” write Naveed Sattar (University of Glasgow, UK) and colleagues in a commentary linked to the study in The Lancet Diabetes & Endocrinology.
But while congratulating the researchers on the trial, they echo the need for caution, especially with regards to cardiovascular safety.
During the study, the researchers had a number of safety triggers in place, and there was a marked difference between the groups in the number of participants meeting the trigger of hematocrit of 54% or greater – 22% of the testosterone group versus just 1% of the placebo group.
Sattar et al call this “a notable finding since increased haematocrit levels have been associated with an increased risk of coronary events.”
They write: “[O]ne of the key goals in preventing diabetes is to slow progression to cardiovascular pathology, and in view of the major uncertainties about the vascular effects of testosterone, outcome trials are necessary before any conclusions can be drawn.”
But the commentators conclude: “In the meantime, clinicians should be glad that affordable, alternative interventions for preventing type 2 diabetes exist, including metformin but in particular lifestyle interventions, which have been shown to reduce future vascular outcomes and extend life.”
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