Muscle Function Increases, Fat Decreases With Testosterone Therapy

Testosterone replacement therapy is associated with improved body composition, preserved knee extensor muscle mechanical function, and increased levels of testosterone in aging men with type 2 diabetes and lower levels of bio-available testosterone, according to a recent study.

For their study, the researchers assessed 39 men age 50 to 70 years with type 2 diabetes and bio-available testosterone levels of less than 7.3 nmol/L who were being evaluated at an academic tertiary-care medical center. Patients were randomly assigned to receive either testosterone replacement therapy via testosterone gel (n = 20) or placebo (n = 19) for 24 weeks.

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Various methods were used to determine muscle mechanical function. Gait speed was used to evaluate physical function, and whole-body dual-energy x-ray absorptiometry was used to examine body composition. Fasting blood samples were collected to assess levels of total testosterone, bio-available testosterone, free testosterone, and sex hormone-binding globulin.

Results indicated that participants receiving testosterone replacement therapy had demonstrated increased maximal isometric contraction, rate of force development, and maximal dynamic contraction, vs participants on placebo. However, the researchers did not observe any changes in leg power or gait speed. Testosterone replacement therapy was also associated with an increase in total lean body mass and lean leg mass, and a decrease in total fat mass and leg fat mass, compared with placebo.

Participants on testosterone replacement therapy had also experienced increased levels of total testosterone, bio-available testosterone, and free testosterone, and decreased levels of sex hormone-binding globulin, vs those on placebo.

“Knee extensor muscle mechanical function was preserved, and body composition improved substantially during testosterone replacement therapy for 24 weeks compared with placebo, whereas physical function (gait speed) was unchanged in aging men with type 2 diabetes and lowered [bio-available testosterone] levels,” the researchers concluded.

—Christina Vogt


Magnussen LV, Hvid LG, Hermann AP, et al. Testosterone therapy preserves muscle strength and power in aging men with type 2 diabetes—a randomized controlled trial [Published online September 15, 2017]. Andrology. doi:10.1111/andr.12396.