Gastric bypass helps treat diabetes, but has risks

Two years after surgery, people who have had gastric bypass have better control of their type 2 diabetes than people who did not, but also had higher risk of infections and bone fractures, according to a new international study.

"Some doctors had thought that gastric bypass could cure diabetes, but that did not happen for most of our patients," said coauthor Dr. Charles J. Billington. "Also unexpected was the extent of complications in the bypass patients," said Billington, of the endocrinology and diabetes division at the University of Minnesota, Minneapolis.

"Gastric bypass now appears to have less strong positives and more worrisome negatives than previously thought," he told Reuters Health by email.

The results are based on two years of the ongoing Diabetes Surgery Study.

Between 2008 and 2011, researchers recruited 120 obese patients aged 30 to 67 years old with type 2 diabetes at three teaching hospitals in the US and one in Taiwan.

They were randomly divided into two groups: lifestyle and medical diabetes management, or lifestyle and medical management in addition to gastric bypass surgery.

The lifestyle group met regularly with a dietitian or nurse, were instructed to weigh themselves and record their food intake daily while ramping up daily exercise to a goal of 325 minutes of activity, like walking, per week.

They also met with an endocrinologist and took medicines for blood sugar control, cholesterol and blood pressure as needed.

The gastric bypass group had access to the same resources in addition to weight-loss surgery.

Two years after surgery, 24 of the patients in the gastric bypass group achieved lower HbA1c, as well as lower low-density lipoprotein cholesterol and lower blood pressure. Together these indicated improved diabetes control, relative to eight patients in the comparison group.

There were eight infections in the gastric bypass group, compared to four in the comparison group, and the bypass group had seven serious falls with five fractures compared to three serious falls and one fracture in the comparison group, as reported in The Lancet Diabetes and Endocrinology. All the fractures happened among women.

Nutritional deficiencies of iron, calcium and vitamin D were more common in the gastric bypass group.

"I assume nutritional deficiencies are likely to be an even greater problem in general practice," said Markku Peltonen of the National Institute for Health and Welfare in Helsinki, Finland, who wrote an editorial accompanying the new results.

Gastric bypass may reduce bone strength because of reduced calcium absorption from food, Billington said. "Supplements need to be adjusted to be sure they are enough," he said.

Carefully taking nutritional supplements, regularly checking with your doctor about the adequacy of these supplements, and maintaining physical fitness reduces the risk of adverse events, he said.

"We are still not sure which are the best patients with diabetes to consider for gastric bypass or other bariatric surgery," Billington said. Hopefully this and other studies will help identify which patients are best suited for gastric bypass to treat diabetes, he said.

"It is important that patients understand that bariatric surgery has other consequences beside the weight loss itself," Peltonen said. "Realistic expectations about the effects of surgery, acknowledging the possibility of adverse events, and the need for continuous monitoring of patients after surgery needs to be discussed with the patients."