Men's Health

The Link Between Low T And Type 2 Diabetes Is Becoming Clearer

And testosterone therapy can help some diabetic men get healthy.

by Isobel Whitcomb
Ariela Basson/Fatherly; Getty Images

About one in 10 people in the U.S. have type 2 diabetes — the majority of whom are men. These men disproportionately struggle with another condition: low testosterone. As many as 40% of men with type 2 diabetes also have low testosterone, compared to between 6% and 13% of men in the general population, according to the Cleveland Clinic. Emerging evidence suggests that for men struggling with both type 2 diabetes and low T, boosting testosterone could play a role in getting healthy, or preventing diabetes from progressing.

A recent “audit” had health care providers around the world submit their results from using testosterone therapy in diabetic men. The results, presented at this year’s Annual Meeting of The European Association for the Study of Diabetes, included data from 428 men who were followed for between three months and two years. Men who had been on testosterone therapy the longest experienced the largest drop in HbA1c, or average blood sugar levels over the past 3 months; but although that improvement was substantial, they remained diabetic.

Experts caution that more data is needed on how well this therapy works for controlling diabetes — especially because the audit wasn’t a true experimental study — but that testosterone therapy could have real benefits for a subset of men with diabetes. So, if you have type 2 diabetes, could testosterone therapy be right for you?

The Diabetes And Testosterone Connection

It’s a mystery why a disproportionate number of men with type 2 diabetes have low testosterone, and what the relationship between the two conditions is. But there does seem to be a connection.

Both diabetes and low testosterone are independently related to having too much body fat, says David D’Alessio, M.D., chief of endocrinology and metabolism and an endocrinologist specializing in type 2 diabetes at the Duke University School of Medicine. So it’s possible that obesity increases the risk of both conditions and that the link between diabetes and low T really has to do with their relationships to obesity.

Another possibility is that low T could be an unfortunate side effect of type 2 diabetes. “People with diabetes have a lot of long-term complications,” D’Alessio says. Those include chronic infections, heart disease, and kidney problems. These complications could cause the reproductive system to shut down — including the production of testosterone.

Certain therapies for diabetes seem to exacerbate low testosterone. Some research suggests that metformin, a drug used to lower blood sugar, also lowers testosterone in men. So low T may not only be connected to type 2 diabetes itself, but also to its treatments.

What happens, then, when men with diabetes and low testosterone boost their levels of the sex hormone? The question is controversial among experts. Although the evidence is strong that men with type 2 diabetes are more likely to have low testosterone, “the question of whether higher testosterone levels protect against diabetes, or whether it improves diabetes in men, is much less clear,” says Eric Orwoll, M.D., an endocrinologist at Oregon Health and Sciences University. That said, recent research suggests testosterone therapy could help men with type 2 diabetes get healthy.

In an Australian study published in the journal The Lancet, more than 1,000 men were randomly chosen to receive either testosterone therapy or a placebo injection. All of them were overweight, low on testosterone, and had either type 2 diabetes or pre-diabetes — a condition in which blood sugar is high, but not high enough to warrant a diabetes diagnosis. All took part in a weight loss and exercise program. After two years, 21% of men in the placebo group had type 2 diabetes, compared to 12% in the testosterone group. Both groups of men lost weight and saw their blood sugar decrease, on average, but men who received testosterone injections had slightly larger improvements — plus, they gained muscle mass and their sexual function increased too.

“[This study] is well done and pretty convincing,” Orwoll says. For men with diabetes and low T, it’s plausible that testosterone therapy has an indirect effect on their diabetes by improving overall health, he adds. There’s good evidence that testosterone therapy decreases body fat and increases muscle mass, and these changes are important for diabetes recovery.

Not all studies are as convincing in their findings, though. In a study conducted in Germany, scientists followed 178 men with diabetes and low testosterone who decided to receive hormone therapy. Over 11 years, one third of the men went into remission. However, the smaller sample size and the fact that the men knew what they were getting — which could have contributed to their improvement — make this study’s results less compelling, Orwoll says. Additionally, the researchers received funding from the manufacturer of the testosterone used in the study, which could potentially bias the results.

If You Have Type 2 Diabetes, Should You Try Testosterone Therapy?

Most studies on testosterone therapy for diabetes share similar weaknesses to the German study. For that reason, D’Alessio and Orwoll agree that diabetes and low testosterone alone aren’t reasons to opt for hormone therapy. “To date, the effects seem modest; I don’t think we are close to using T as a primary treatment for prediabetes/diabetes,” D’Alessio wrote in an email.

However, they both would recommend testosterone therapy to a subset of men with low T and diabetes. Low testosterone can have a myriad of health effects, from low libido to depression to muscle loss. If you’re struggling with these issues, they recommend getting your testosterone levels checked and potentially starting testosterone therapy. As your symptoms improve, you might see your blood pressure decrease; you might exercise more. These healthy changes and the testosterone itself could very well keep your blood sugar in check.

If you do have both diabetes and symptoms related to low T and decide to start testosterone therapy, “you’re probably going to feel better,” D’Alessio says.