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Obesity surgery is most effective intervention for reversing diabetes

Bariatric surgery found to be better than intensive lifestyle and drug interventions in mild to moderate obesity

Ingrid Torjesen

Friday, 18 March 2016

Bariatric surgery is much more effective than an intensive lifestyle or medication intervention at reversing type 2 diabetes in patients with mild-to-moderate obesity, a randomised study* published in Diabetologia has found.

Observational studies have suggested that Roux-en-Y gastric bypass (RYGB) - a type of bariatric surgery - can reverse type 2 diabetes, through mechanisms beyond just reduced food intake and body weight, so the researchers decided to investigate by compared RYGB to an intensive lifestyle and medical intervention (ILMI) for type 2 diabetes.

The researchers screened 1,808 adults meeting inclusion criteria (age 25-64, with type 2 diabetes and a BMI 30-45 kg/m2). It was difficult to get patients to agree to be randomised to surgery or non-surgery, so only 43 were randomly allocated in a 1:1 ratio to RYGB or ILMI. A total of 23 volunteers were assigned to RYGB and 20 to ILMI. Of these, 11 withdrew before receiving any intervention, leaving 15 in the RYGB group and 17 in the IMLI group. The groups were equivalent regarding all baseline characteristics, except that the RYGB cohort had by chance a longer diabetes duration (11.4 versus 6.8 years).

The lifestyle intervention involved 45 minutes or more of aerobic exercise 5 days or more per week, a dietician-directed weight- and glucose-lowering diet, and optimal diabetes medical treatment for 1 year. Although treatment allocation could not be blinded, outcomes were determined by a blinded adjudicator.

At one year weight loss was 25.8% for RYGB versus 6.4% ILMI groups, respectively. The ILMI exercise programme yielded a 22% increase in exercise capacity, whereas after RYGB exercise capacity was unchanged. Diabetes remission at one year was 60% with RYGB versus 6% with ILMI.

The HbA1c decline over 1 year was only modestly more after RYGB than ILMI: from 7.7% to 6.4% vs 7.3% to 6.9%, respectively. However, this drop occurred with significantly fewer or no diabetes medications after RYGB.

The authors said: "These results apply to patients with a BMI of 30-35 kg/m2, as well as to more obese patients, and our study and others show that neither baseline BMI nor the amount of weight lost dependably predicts diabetes remission after RYGB, which appears to ameliorate diabetes through mechanisms beyond just weight reduction. These findings call into serious question the longstanding practice of using strict BMI cut-offs as the primary criteria for selection for bariatric surgery among patients with type 2 diabetes."

Prof Yoon Loke, Professor of Medicine and Pharmacology, Norwich Medical School, UEA, said: “This is a very small study with only 32 patients. Follow-up was for a year, which seems a rather short time for a study looking at long-term conditions such as diabetes and obesity.

“The short follow-up and small numbers means that we do not know if the problem with diabetes will crop up again in future, of if the benefits of surgery are short-lived.

“Similarly, the study is too small to show whether surgery is safer or more dangerous than other treatments.”

* Cummings DE, et al. Gastric bypass surgery vs intensive lifestyle and medical intervention for type 2 diabetes: the CROSSROADS randomised controlled trial. Diabetologia pp 1-9, first online: 17 March 2016. DOI: 10.1007/s00125-016-3903-x

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