Benefits of Bariatric Surgery for Diabetes Persist for Up to 5 Years, Studies Show

Two long-term follow-up studies of type 2 diabetes patients who underwent bariatric surgery have found that significant metabolic benefits generally persist for up to 5 years or longer.

Both studies, presented at the 2011 American Diabetes Association meeting, found that diabetes remits or significantly improves in about 4 out of 5 cases. One of the studies, however, found that by 5 years post-surgery, relapse occurred in about one-third of those who initially remitted, most often in those who had undergone gastric banding rather than Roux-en-Y, or whose diabetes had been most severe and long established.

“To be in complete remission for 5 years had never been thought to be possible,” said the senior author of one of the studies, Philip Schauer, MD, director of the bariatric surgery program at the Cleveland Clinic.“It’s as close to a cure as you can get.”

Still, he said, the studies show that the dramatic initial benefits previously reported in short-term studies do not always persist.

“You can look at this glass as half full or half empty,” Dr. Schauer said, noting that after 5 years, 42% of the patients remained in complete remission, while an additional 42% continued to show significant benefits. “I definitely look at it as half full.”

But the second, much larger study found that of those who initially experienced remission after surgery, 36.7% relapsed within 5 years. “Caution should be advised in recommending bariatric surgery as a ‘cure’ for type 2 diabetes mellitus in severely obese patients,” the study (abstract 1190-P) concluded.

The study involved 6 sites across the country, although like Dr. Schauer’s study, it was neither prospective nor randomized. A total of 4,353 adults with severe obesity and type 2 diabetes prior to bariatric surgery were identified in medical records and compared to 62,167 non-surgical subjects. Even with the relapses, the 5-year remission rate remained 18.7 times higher in surgical patients than in those treated medically (95% confidence interval 17.1 to 20.4).

Dr. Schauer’s study (abstract 1896-P) identified 42 patients at his institution who had type 2 diabetes and morbid obesity prior to undergoing bariatric surgery, and for whom 5-year follow-up data was available. Twelve of the patients underwent gastric restriction, while the remaining 29 underwent Roux-en-Y.

At 5 years post-surgery, 84% overall were either in remission or showed significant continued metabolic improvement, although that rate was just 66% for patients who had undergone the restrictive procedure.

Remission was defined as a fasting blood glucose level of less than 120 without medications. In those who remitted, average fasting glucose fell from 122.3 to 111.3. In those who improved but did not remit, average fasting glucose fell from 134.9 to 122.1. In those for whom no significant improvement was seen, fasting glucose still fell slightly on average, from 164.7 to 160.3.

“The patients who started out with higher BMI, of nearly 50, and those who lost more weight are the ones who did better with their diabetes long-term,” said Shai Meron-Eldar, MD, a research fellow at the Cleveland Clinic’s Bariatric and Metabolic Institute and co-author of the paper. “Patients who started at lower BMI and lost less weight are the ones who were more likely to show no change in their disease diabetes.”

Dr. Schauer is now leading a prospective trial of patients with diabetes and a BMI of 27 to 40, randomizing them to either intense medical therapy, gastric bypass, or sleeve gastrectomy. “Hopefully we’ll be able to present the results at ADA next year,” he said.

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