Study Finds Gastric Bypass Leads to Diabetes Remission in More than 50% of Patients

Jonathan Purnell, MD

A study of more than 2250 patients from 10 hospitals is highlighting the benefits of weight loss surgery, particularly gastric bypass, on remission of type 2 diabetes in severely obese patients.

Results of the study, which examined the effects of Roux-en-Y gastric bypass (RYGB) and laparoscopic gastric banding (LAGB), suggest more than half the patients undergoing RYGB achieved long-term remission and also offer insight into characteristics and predictors of diabetes remission in patients undergoing either procedure.

"If a patient with type 2 diabetes is considering weight loss surgery, choosing gastric bypass soon after diagnosis can increase their chance of remission or achieving a blood sugar level that does not need treatment," said lead investigator Jonathan Purnell, MD, of the Oregon Health & Science University, in a statement. "Our large study confirms the importance of weight loss on inducing diabetes remission, but also finds gastric bypass has benefits independent of weight. If we can understand what these benefits are, it could lead to new diabetes treatments."

After previously publishing data comparing 3-year diabetes remission rates following LAGB or RYGB, Purnell and a team of colleagues sought to evaluate long-term remission and predictors of diabetes remission in a cohort of severely obese patients. Their previous study, the Longitudinal Assessment of Bariatric Surgery-2 (LABS-2) study, enrolled 2467 adult participants from 2006-2009 at 10 centers across the US. From this study, investigators identified a total of 2256 patients with at least one year of follow-up.

Of the 2256 included in the current study, 827 (37%) had diabetes and 50% of had information related to duration of diabetes available. Of those with diabetes, 43% reported taking one non-insulin medication, 32% reported taking 2 or more non-insulin medications, and 36% reported taking insulin. For the purpose of analysis, investigators defined being nondiabetic at follow-up as not taking diabetes medications, not self-reporting a diagnosis of diabetes, and must have an HbA1c of 5.7% or less or a fasting glucose of 5.6 mmol/L or less if HbA1c was not available.

Upon analysis, investigators found diabetes remission occurred in 57% (46% complete, 11% partial) after RYGB and in 22.5% (16.9% complete, 5.6% partial) after LAGB at 7 years. Compared to diabetics who did not achieve complete or partial remission during the first year of follow-up, results indicated those who did were more likely to be younger, have shorter diabetes duration, lower HbA1c levels, and were less likely to need more than one non-insulin diabetes medication or use insulin.

During the follow-up period, diabetes remission peak between 2-3 years after both procedures before declining during the 7-year follow-up period. The peak decline among those undergoing RYGB was 62% remission (51% complete, 11% partial) and this decline to 57% (46% complete, 11% partial) at year 7. Among those undergoing LAGB, diabetes remission peaked at 29.1% (22.6% complete, 6.5% partial) before declining to 22.5% (16.9% complete, 5.6% partial) at year 7. Results indicated post-operative diabetes remission for both RYGB and LAGB groups was more likely in patients who were younger, had shorter diabetes duration, and had better baseline HbA1c levels that required fewer diabetes medications or need for insulin at baseline.

Further analysis suggested reduced HOMA-IR could serve as a predictor of remission among patients undergoing LAGB while increased HOMA-B helped to predict remission in patients undergoing RYGB. In analyses adjusted for weight loss, results indicated the probability of diabetes remission was greater among those undergoing RYGB than LAGB at all follow-up time points, increasing from an adjusted relative risk of 1.86 the first post-operative year to 3.96 at 7 years.

This study, “Diabetes Remission Status During Seven-year Follow-up of the Longitudinal Assessment of Bariatric Surgery Study,” was published in The Journal of Clinical Endocrinology & Metabolism.