Testosterone treatment may improve body composition, glucose metabolism and sex drive in some older men at high risk for type 2 diabetes (T2D), but the benefits require participation in a lifestyle program, according to a study presented Saturday at ENDO 2026, the Endocrine Society’s annual meeting in Chicago, Illinois.
More than 40 million people in the United States and hundreds of millions of people worldwide have been diagnosed with T2D, and it is estimated that more than 115 million adults in the United States have prediabetes. T2D is most commonly diagnosed in adults over 45 years of age. It is strongly associated with abdominal obesity and loss of muscle mass and strength. Early detection and treatment can reduce the risk of developing complications of T2D.
Testosterone treatment alone is not a substitute for lifestyle interventions, weight management, or standard diabetes prevention in older men with central obesity and prediabetes, or early T2D. ”
Gary Wittert, MBBch., MD, lead study author, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
The findings are based on a substudy of the Randomized, Double-Blind, Placebo-Controlled Testosterone for Type 2 Diabetes Prevention Study (T4DM) published in 2021, which included 1,007 men aged 50 to 74 who were at high risk of developing T2D or newly diagnosed with T2D. The T4DM study showed that testosterone and lifestyle interventions reduced the likelihood of developing diabetes after two years, but the new study provides deeper insight into a subset of 121 patients who were studied for an additional two years. Wittert led the T4DM study.
The new study expanded the T4DM study among a subgroup of 121 participants who chose to continue blinded treatment for an additional two years without continued enrollment in the lifestyle program. This study aimed to determine the long-term effects of testosterone treatment on blood glucose levels, measures of obesity, skeletal muscle mass and strength, sexual function, and safety.
Results show that most of the effects of glycemic control appeared during the first 2 years and diminished by the 4th year. Glycemic control remained significantly better than in the placebo treatment group. The improvements in body composition (fat loss and muscle gain) and sex drive that occurred during the first two years were maintained through four years.
Testosterone did not clearly improve overall quality of life compared to placebo after 2 or 4 years. Overall, quality of life was similar between both study groups over the 4-year period. No new safety concerns were identified.
“Our data show that in the specific group of men aged 50 and older we studied, testosterone alone was not a substitute for dietary and exercise changes, and was most beneficial when combined with a lifestyle program. It may also lead clinicians to look more closely at a man’s metabolic health, waist circumference, muscle health, sexual symptoms, and testosterone status as related issues rather than treating them in isolation,” Wittert explained.
