Study: In severely obese teen males, bariatric surgery reverses low testosterone

BUFFALO, N.Y. — A new study led by University at Buffalo researchers shows that bariatric surgery not only treats obesity and reverses Type 2 diabetes, it also reverses low testosterone levels in obese teen males.

The finding is important because of testosterone’s role in reducing inflammation and increasing insulin sensitivity, in addition to its sexual and fertility functions.

“We have shown that in severely obese teen males, bariatric surgery and weight loss led to normalization of testosterone concentrations,” said Paresh Dandona, MD, senior author on the study and SUNY Distinguished Professor at the Jacobs School of Medicine and Biomedical Sciences at UB. “This is the first major study in obese adolescents examining the effect of bariatric surgery in this age group, leading to normalization of testosterone concentrations.”

The concept of low testosterone levels, known as hypogonadism, in males with Type 2 diabetes and obesity originated over a decade ago with Dandona, who sees patients at UBMD Internal Medicine.

“Considering that one-third of the American population is obese, prevention and treatment of hypogonadism remains a major task,” he said. He noted that previous work by his team has demonstrated that testosterone replacement results in loss of adiposity and an equivalent buildup of muscle.

The current study involved 34 severely obese teen males who underwent bariatric surgery, and were followed for five years. Prior to surgery, 73% of them had subnormal free testosterone levels, below .23 nanomoles per liter (nmol/L). Two years later, only 20% had subnormal free testosterone concentrations and five years later, that percentage rose to 33% due to participants who regained some of the weight they had lost.

The study was part of the Teen-Longitudinal Assessment of Bariatric Surgery (Teen-LABS), the largest national study to examine the effects of bariatric surgery on adolescents.

“These boys, if they persist with obesity, will suffer with a lifetime of impotence and infertility,” said Dandona.

The discovery of this syndrome of hypogonadism in Type 2 diabetes was made by Dandona’s group at UB in 2004. In 2010, the group demonstrated that testosterone levels are 50% lower in obese versus normal boys, and in 2016, the group demonstrated that men with hypogonadism and Type 2 diabetes had 35% additional insulin resistance. Dandona added that a previous study has also shown that obese boys have been shown to have smaller penises than boys who aren’t obese, an additional indication of compromised sexual function.

“Physicians should realize that 25% of non-diabetic obese men and 33% of Type 2 diabetics suffer from hypogonadism,” Dandona said. “The U.S. has nearly 35 million diabetics and over 100 million obese individuals. Every Type 2 diabetic, obese male should be tested for testosterone deficiency.”

The study was funded by the Division of Endocrinology in the Department of Medicine in the Jacobs School at UB and by Saint Louis University.

Sandeep Dhindsa, MD, first author on the paper and formerly a fellow in the Division of Endocrinology, Diabetes and Metabolism in the Jacobs School, is now chief of endocrinology at Saint Louis University. Other UB co-authors are Husam Ghanim, PhD, in the Department of Medicine, and Carroll Harmon, MD, in the Department of Pediatrics and John R. Oishei Children’s Hospital. Additional co-authors are from Saint Louis University, the University of Colorado and Quest Diagnostics at the Nichols Institute.