Diabetes Remission With Bariatric Surgery Independent of BMI

Miriam E Tucker

December 03, 2015

VANCOUVER, British Columbia — Use of bariatric surgery early in the course of type 2 diabetes might offer a better chance for remission, even at body mass indexes down to 30 kg/m2, a new analysis suggests.

The findings were presented December 1 here at the World Diabetes Congress 2015 by Geltrude Mingrone, MD, PhD, associate professor of internal medicine and chief of the division of obesity and related disorders at the Catholic University, School of Medicine, Rome, Italy. The paper was simultaneously published online in Diabetes Care.

The analysis of pooled data on 727 patients from the prospective, controlled Swedish Obese Subjects (SOS) study and two additional randomized clinical trials suggests that shorter diabetes duration, lower fasting glycemia before surgery, and diversionary surgical procedures independently predict remission of type 2 diabetes, while lower baseline HbA1c and waist circumference predict improved glycemic control following bariatric surgery.

All three studies found that surgery was more effective than medical therapy in producing both diabetes remission and improved glycemic control and that patients with BMIs as low as 30 kg/m2 achieved similar benefit to those with BMIs between 30 and 35 kg/m2.

Current criteria for bariatric surgery in people with type 2 diabetes include BMI greater than 40 kg/m2 or 35 to 40 kg/m2 with poorly controlled diabetes.

"There is a need to redefine the eligibility criteria for bariatric surgery in patients with type 2 diabetes, since BMI does not predict diabetes remission or glycemic control," Dr Mingrone told Medscape Medical News.

"Until now the only criterion for selecting patients…for bariatric surgery is a BMI > 35 if associated with uncontrolled diabetes. We show that baseline BMI does not predict diabetes remission rate at all, while the duration of diabetes and the type of surgery are much better predictors, together with the baseline degree of insulin resistance and waist circumference (a rough measure itself of insulin resistance). In other words, the shorter the duration of diabetes and the lower the insulin resistance before surgery, the higher the diabetes remission rate."
However, prospective studies with more sophisticated measures of insulin resistance are still needed, he added.

Session moderator and Diabetes Care editor William T Cefalu, MD, executive director, Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, told Medscape Medical News, "This study does challenge the current paradigm that we look only at BMI when considering bariatric surgery….The remission rate over 2 years may be independent of the BMI and may be based on other predictive factors."

Findings Independent of BMI

Of the total 727 patients with type 2 diabetes, 415 were surgically treated. The surgical procedures were 227 vertical banded gastroplasties, 91 gastric bandings (adjustable or nonadjustable), 77 Roux-en-Y gastric-bypass procedures, and 20 biliopancreatic diversions.

For comparison, the investigators combined the patients receiving the first two techniques, with purely gastric components, into one group, and the latter two, in which gastric content is diverted distally into the small intestine, into a second group, named "diversionary procedures."

At 2 years, 10.4% of the surgical patients and 19.9% of the medically treated patients had dropped out. In all, diabetes remission — defined as a fasting plasma glucose less than 5.6 mmol/L without pharmacological treatment — was achieved in 14.4% of the medication group vs 63.7% in the surgical arm (P < .001).

By surgical type, 76% of those with diversionary procedures achieved remission, vs 60% with gastric-only techniques (= .016).

"Probably, as demonstrated by many pathophysiologic studies, it is the bypass of the duodenum and jejunum that improves insulin resistance," Dr Mingrone said.

Tight glycemic control, defined as fasting glycemia less than 7 mmol/L without pharmacological therapy, occurred in 85% of the diversionary-surgery group and 78% of the gastric-only surgery group. By contrast, 40% of medically treated patients achieved tight glycemic control at 2 years.

For the total study population, baseline younger age, shorter diabetes duration, lower fasting glycemia, and nonuse of diabetes drugs all predicted a greater chance of remission at 2 years. When the analysis was divided by medication vs surgery and by surgery type, age was no longer significant.

When the total study population was stratified by baseline BMI, the chance of remission was 2.9-fold greater for those with BMI greater than 40 kg/m2 compared with BMI between 35 and 40 kg/m2, but there was no significant difference between the latter group and those with BMI below 35 kg/m2.

Patients who achieved diabetes remission lost more weight (25% vs 17%) and experienced improved waist circumference (18% vs 13%) and better insulin sensitivity than did those not achieving remission.

Dr Cefalu told Medscape Medical News that this study's strengths are the database of studies and the 2-year observation period for remission.

"Clearly, this study, as others, continues to demonstrate the effectiveness of metabolic surgery for diabetes control."

Dr Mingrone said that while there is now enough literature to prove that bariatric surgery is effective in inducing diabetes remission and in improving glycemic control, "endocrinologists probably want to know better the complications of bariatric surgery both in the short and in the long term and in much larger populations than in the relatively small studies published.

"The major problem in this regard is that for a drug there is a pharmaceutical company paying for the drug study in big population trials, while for bariatric surgery only small grants are available from public funds," he added.

Dr Mingrone is a member of the board of Fractyl Labs and has received research grants from AstraZeneca. Dr Cefalu is a consultant for Intarcia Therapeutics and Sanofi and has been a principal investigator of studies for GlaxoSmithKline, AstraZeneca, and Janssen.

Diabetes Care. Published online December 1, 2015. Article

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