Testosterone Treatment and Type 2 Diabetes

There is a distinct connection between serum testosterone concentrations and increased type 2 diabetes risk. This correlation is especially noteworthy among overweight and obese men, as excess weight is a risk factor for low serum testosterone concentrations.

It stands to reason, then, that treating men, especially overweight and obese men, with testosterone may help prevent or reverse type 2 diabetes. To determine if testosterone treatment may be effective in this use—beyond the benefits of lifestyle changes—researchers conducted a study.

The Study

Over two years, this placebo-controlled study was conducted at six different tertiary care centers in Australia. 19,022 men were pre-screened, and the 1,007 participants who were included ranged from 50 to 74 years old. They all had waists that measured 95 cm or more in circumference.

All of the included men had a serum testosterone concentration equal to or less than 14·0 nmol/L but did not have pathological hypogonadism. The participants also had impaired glucose tolerance or recently diagnosed type 2 diabetes.

Every participant was enrolled in a lifestyle program, then randomly assigned to either a placebo or an injection of testosterone undecanoate intramuscularly. These injections occurred at the beginning of the study, after six weeks, and then every three months for the next two years.

Type 2 diabetes and the mean change in 2-h oral glucose tolerance test results after two years.

Results

The group receiving testosterone treatment showed a lower risk of heightened 2-h glucose compared to the placebo group (55 of 443 versus 87 of 413). The mean change in 2-h glucose from the baseline measurements was more substantial in the testosterone group, as well. These effects of treatment were independent of the serum testosterone levels present at the baseline.

Safety was a concern during the study. For example, hematocrit of greater than 54% occurred in only six placebo participants compared to 106 in the testosterone group. Serious adverse events were higher in the testosterone group, as well, with 55 participants experiencing said events compared to 37 in the placebo group.

What it Means

For older, overweight men, testosterone treatment reduced the likelihood of type 2 diabetes, whether through prevention or reversal. However, there were safety concerns that may make this treatment method limited and unsustainable. More research is needed to determine the overall safety, especially long-term, and cardiovascular impact of testosterone treatment for this purpose.