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STAMPEDE: 5 years after bariatric surgery, increased testosterone levels persist
Men with obesity and poorly controlled type 2 diabetes randomly assigned to bariatric surgery saw a near 50% increase in free testosterone that persisted 5 years after surgery vs. men assigned to medical therapy, according to an analysis of the STAMPEDE trial.
“Chronic testosterone supplementation has been the mainstay for treatment of male hypogonadism and is effective in improving libido and body composition, but cardiovascular and prostate disease risks are associated with long-term therapy,” Sangeeta Kashyap, MD, of the department of endocrinology, diabetes and metabolism at Cleveland Clinic, and colleagues wrote. “Recent studies demonstrate improved testosterone levels and fertility in men undergoing bariatric surgery. Increased testosterone levels after bariatric surgery have been attributed to weight loss primarily, but associations with changes in gonadotropins and inflammatory markers have been inconsistent across multiple studies. More importantly, these findings thus far have not been supported by long-term data from a randomized controlled trial.”
The researchers analyzed data from 32 men with obesity (mean BMI, 36.7 kg/m²) and type 2 diabetes enrolled in the STAMPEDE trial, a single-center study in which patients were randomly assigned to bariatric surgery (n = 24; Roux-en-Y or sleeve gastrectomy) or intensive medical therapy (n = 8). Mean age of the cohort was 52 years, 81% were white and mean HbA1c was 9.6%. No patients reported taking medications that could alter testosterone levels at any time during the study. Participants provided blood samples at baseline and at 5-year follow-up. Researchers measured levels of testosterone, sex hormone-binding globulin, estradiol, luteinizing hormone and high-sensitivity C-reactive protein, as well as leptin, free testosterone and HbA1c.
The average baseline concentrations of total testosterone and free testosterone were 310 ng/dL and 9.1 ng/dL, respectively.
At 5 years, patients assigned to bariatric surgery saw a greater increase in total testosterone vs. those who were assigned to medical therapy (84.1% vs. 9.6%; P = .008), as well as a greater increase in free testosterone (47.4% vs. –2.2%; P = .013). Patients assigned to bariatric surgery also saw a markedly greater reduction in body weight (–19.9% vs. –3.9%; P < .001), HbA1c (–25.1% vs. –0.4%; P = .017) and leptin levels (–50.9% vs. 7%; P = .037) vs. those assigned to medical therapy.
In the combined cohort, 15 patients experienced less than 15% 5-year weight loss, and 17 patients experienced greater than 15% weight loss. Patients with greater than 15% weight loss saw a greater increase in total testosterone vs. those who had less weight loss (210 ng/dL vs. 86 ng/dL; P = .04); however, this subgroup did not experience an increase in free testosterone (3.8 ng/dL vs. 0.42 ng/dL; P = .093).
“Surgically induced weight loss benefits the treatment of male hypogonadism related to diabetes,” Kashyap told Endocrine Today. “These benefits were noted 5 years following having bariatric surgery. Durable weight loss is a benefit of bariatric surgery and is often difficult to achieve with medical weight-loss therapies.”
The researchers noted that the observed increase in testosterone may lead to multiple benefits in addition to increased libido, including long-term glycemic control and cardiovascular risk protection in men following bariatric surgery. – by Regina Schaffer
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Sangeeta R. Kashyap, MD, can be reached at the department of endocrinology, diabetes and metabolism at Cleveland Clinic, 9500 Euclid Ave., Cleveland, OH 44195; email: kashyas@ccf.org.
Disclosures: The STAMPEDE trial was funded by Ethicon, part of the Johnson & Johnson family of companies, through its Metabolic Applied Research Strategy (MARS) program. Kashyap reports she receives grant support from Covidien and Janssen, and grant support and personal fees from Ethicon Endosurgery outside the submitted work. Pham reports he receives consulting fees from FundRX. Please see the full study for the other authors’ relevant financial disclosures.