Metformin, testosterone, or both reduce insulin resistance in obese men with low testosterone: Study
Spain: A combination of metformin+testosterone, or metformin and testosterone alone reduced insulin resistance at 1 year compared to placebo in obese men with low testosterone concentrations, without additive benefit, says a recent study published in the journal Metabolism.
Previous studies have shown that obese men tend to be insulin resistant and often have low-normal concentrations of testosterone. Considering this, José Carlos Fernández-García, and colleagues from Spain conducted a 1-year, parallel, randomized, double-blind, placebo-controlled trial with the objective to evaluate potential therapeutic strategies for low testosterone in men with obesity.
In the trial, they evaluated the independent and combined effects of testosterone and metformin in 106 obese men aged 18-50 years, who had low testosterone levels and no diabetes mellitus. Change in insulin resistance, measured as Homeostasis Model Assessment for Insulin Resistance (HOMA-IR) index was the primary outcome of the study. Secondary outcomes included changes in total and free serum testosterone, metabolic variables, body composition, erectile function, and health-related quality of life (HRQoL).
Based on the study, the researchers reported the following findings:
- In the intention-to-treat analysis, the HOMA-IR index decreased significantly in all active groups compared to placebo (metformin -2.4; testosterone -2.7; combination -3.4).
- Combination therapy was not superior to testosterone alone in decreasing insulin resistance (-0.7).
- Only the combination of metformin plus testosterone significantly increased total and free testosterone concentrations, compared to placebo.
- No significant changes in body composition (except for a higher decrease in fat mass in the metformin and combination group), metabolic variables, erectile function, or HRQoL were found with any treatment.
The researchers conclude, "metformin only, testosterone only, and the combination of metformin plus testosterone reduced insulin resistance compared to placebo with no evidence of additive benefit in the study population."
The study, however, was limited by a small sample, and its applicability to the population studied.
Small sample
Reference:
Fernández-García JC, Barrios-Rodríguez R, Asenjo-Plaza M, Ramos-Molina B, Molina-Vega M, Guzmán-Guzmán A, Moreno-León L, Yubero-Serrano EM, Rius-Díaz F, Valdés S, Martínez-González MÁ, Jiménez-Moleón JJ, Tinahones FJ. Metformin, testosterone, or both in men with obesity and low testosterone: A double-blind, parallel-group, randomized controlled trial. Metabolism. 2022 Aug 18;136:155290. doi: 10.1016/j.metabol.2022.155290. Epub ahead of print. PMID: 35985506.
