LABS: Surgery Reverses Type 2 Diabetes Best in Young Obese

Marlene Busko

June 27, 2016

NEW ORLEANS — Among adults with type 2 diabetes who had bariatric surgery, diabetes remission was twice as likely after Roux-en-Y gastric bypass than laparoscopic gastric banding, and it was more likely in the heaviest, youngest patients who had had diabetes a short time and were not on insulin, new results indicate.

Jonathan Q Purnell, MD, professor of medicine at Oregon Health & Science University, in Portland, presented these latest 3-year findings from the Longitudinal Assessment of Bariatric Surgery (LABS) study on June 11 at the American Diabetes Association (ADA) 2016 Scientific Sessions, which were simultaneously published online in Diabetes Care.

Added to other recent findings, this study suggests three things, he told Medscape Medical News. First, "bariatric procedures should be considered earlier in discussions with patients regarding management of their diabetes, rather than waiting until patients demonstrate 'medical failure.' "

Second,"Roux-en-Y gastric bypass is superior to a strictly restrictive procedure like the lap band in inducing diabetes remission, at least over 3 years of follow-up."

Third, "this study provides evidence for weight-independent mechanisms affecting glucose metabolism — a very exciting area of exploration of novel factors that could be exploited for future medical therapies of diabetes," he said.

"I agree," added senior author Bruce M Wolfe, MD, a bariatric surgeon, also from Oregon Health & Science University.

The fact that bariatric surgery may reverse diabetes early in the course of the disease contrasts with a consensus document from a group of international experts, which was developed at the 2nd Diabetes Surgery Summit (DSS-II) held in London, UK, in September 2015 and recently published in Diabetes Care (2016;39:861-887), "which is more focused on [bariatric] surgery for poorly controlled type 2 diabetes," Dr Wolfe noted.

More recently, however, six international diabetes groups, backed by almost 40 more medical organizations, have developed what are being called "historic" recommendations calling for bariatric surgery to be added to treatment algorithms for type 2 diabetes.

Bypass and Banding Were Popular at Time of Study

To better understand how bariatric surgery in obese patients with diabetes can lead to diabetes remission and to see what patient characteristics are more predictive of this outcome, Dr Purnell and colleagues analyzed data from the patients in LABS who had type 2 diabetes at baseline.

LABS enrolled 2458 adults who had bariatric surgery at 10 centers in the United States between 2006 and 2009, and of these, 1868 patients had information on diabetes status at baseline and a follow-up visit.

A third of these patients with complete data had type 2 diabetes at baseline. These patients were mostly 40 to 50 years old and 50% had a body mass index (BMI) between 40 and 50 kg/m2.

This was not a randomized study; patients consulted with their surgeons and decided which procedure they wanted.

Of the 627 patients with diabetes at baseline, 466 underwent Roux-en-Y gastric bypass and 140 underwent laparoscopic gastric banding. The remaining 21 patients, who underwent other procedures (sleeve gastrectomy, biliopancreatic diversion with duodenal switch, or banded gastric bypass), were excluded from the current analysis.

At the time of study enrollment, the two most popular bariatric procedures were Roux-en-Y gastric bypass and laparoscopic gastric banding, Dr Purnell explained.

"At that time, the gastric sleeve was still considered the first of a two-step biliopancreatic-diversion procedure. What surgeons noticed, however, was that patients lost a remarkable amount of weight just by having the sleeve gastrectomy alone, and since then, the sleeve gastrectomy has become very popular around the world," he explained.

What Factors Predict Diabetes "Cure" After Surgery?

As has been previously published (JAMA. 2013;10:2416-2425), at 3 years  patients who had undergone laparoscopic gastric banding lost 15% of their initial weight, whereas patients who had undergone gastric bypass lost twice as much (30%).

"There is a tremendous, variable response after these procedures that is often not discussed with patients," Dr Purnell said. Roughly 20% of patients who have laparoscopic gastric banding will end up right back where they started in a few years, and about 10% of patients who have gastric bypass will regain their lost weight.

Diabetes remission was defined as an HbA1c < 6.5% (or fasting blood glucose ≤ 6.9 mmol/L) without any diabetes medications.

At 3 years, 68.7% of patients who had undergone gastric bypass vs 30.2% of patients who had undergone gastric banding had diabetes remission.

The patients who achieved diabetes remission were more likely to be younger (30–50 years old), have a BMI of 50 kg/m2 or higher, and have had diabetes for less than 5 years.

Using insulin at baseline predicted a 73% lower chance of having diabetes remission in the gastric-banding group and a 34% lower chance in the gastric-bypass group.

The study hints that leptin signaling may play a role in diabetes remission, according to the researchers, who add that longer studies are needed to confirm the durability of diabetes remission and unravel the mechanism.

Dr Purnell is on an advisory panel for Novo Nordisk and receives research support from Sanofi. Disclosures for the coauthors are listed in the article.

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Diabetes Care. Published online June 11, 2016. Article

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