Gastric Bypass Reversal: Diabetes Can Return, Even if Weight Doesn't

A letter published Tuesday in Diabetes Care highlights a phenomenon that may offer insights into the physiology of type 2 diabetes (T2D): if gastric bypass is reversed, it seems T2D can return, even if the weight does not.

Researchers from Cleveland Clinic, a leader gastric bypass surgery, wrote about 2 distinct case studies: the first involved a woman whose surgery was reversed after she had abdominal pain and poor nutrition, and the second was a woman who developed a fistula. This first patient had T2D before her original surgery, while the second developed it after surgery but before she came to Cleveland Clinic. Both women had received Roux-en-Y gastric bypass.

In each case, additional surgery had metabolic consequences: the first woman’s glycated hemoglobin (A1C) steadily increased after the reversal procedure, even though she regained only 10 to 15 pounds. The woman regained the weight over 6 months and it stayed the same over 2 years, but her glycemic control was did not: her A1C reached 8.2% after a year, and she required more medication to manage T2D.

The second woman, whose body weight was still 240 pounds, did not need diabetes medications after 6 months, even though her weight fell to only 205 pounds. The researchers wrote that this “might be related to the exclusion of the distal part of the stomach and duodenum, and perhaps was not exclusively dependent on weight loss.”

In June 2016, the American Diabetes Association added “metabolic surgery” to its algorithm to treat patients who have T2D and obesity. The Cleveland Clinic has published studies that show the procedure can reverse T2D in patients with a body mass index as low as 27 kg/m², which would meet the CDC definition of being overweight but not obese. CDC defines obesity as having a body mass index of at least 30 kg/m².

However, as the authors noted in their letter, surgery is not without risk and sometimes requires reversal. The letter is the first to describe the “metabolic consequences” of having the procedure reversed. “Further research is needed to better delineate the role of weight-independent mechanisms on glycemic changes after reoperative bariatric surgery,” the authors wrote.

Reference

Aminian A, Brethauer SA, Parekh N, Abu-Elmagd KM, Schauer PR. Metabolic consequences of restorative surgery after gastric bypass [published online February 7, 2017]. Diabetes Care. https://doi.org/10.2337/dc16-2561.