Weight Loss Surgery May Cut T2D Risk

Published: Nov 2, 2014

By Nancy Walsh, Senior Staff Writer, MedPage Today

Obese individuals who underwent bariatric surgery had an 80% decrease in risk for developing type 2 diabetes, U.K. researchers found.

During a maximum follow-up of 7 years, the incidence of diabetes was 5.7 per 1,000 person-years (95% CI 4.2-7.8) for those who had the surgery compared with 28.2 per 1,000 person-years (95% CI 24.4-32.7) among controls, according to Martin C. Gulliford, FFPH, of King's College London, and colleagues.

After adjustment for variables such as age, sex, body mass index (BMI), hemoglobin A1c, and comorbid conditions, the hazard ratio for diabetes after weight-loss surgery was 0.20 (95 CI 0.13-0.30, P<0.0001), the researchers reported online inThe Lancet Diabetes & Endocrinology.

Previous studies have demonstrated that bariatric surgery could help resolve diabetes, but it hasn't been established whether the surgery could actually prevent diabetes from developing in the first place among the obese.

"The possible effect of bariatric surgery on type 2 diabetes is of particular importance because 3% of severely obese individuals develop diabetes every year," Gulliford and colleagues wrote.

Therefore, to evaluate the potential benefit in routine clinical settings, they analyzed outcomes from the Clinical Practice Research Datalink, which includes electronic health records for more than 5 million people.

From the database, they identified 2,167 individuals whose BMI was 30 kg/m2 or more and who had laparoscopic gastric banding, gastric bypass, or sleeve gastrectomy between 2002 and 2014, matching them with the same number of controls who hadn't had the surgery.

During the maximum 7-year follow-up (median 2.8 years), 38 cases of diabetes were diagnosed in the surgery group and 177 among controls, which represented 4.3% of the surgery group and 16.2% of the controls.

Results were similar for men and women and for different age groups at baseline:

• Men: HR 0.17 (95% CI 0.06-0.46, P=0.0004)
• Women: HR 0.21 (95% CI 0.13-0.33, P<0.0001)
• Ages 20-34: HR 0.14 (95% CI 0.03-0.63, P=0.0102)
• Ages 35-54: HR 0.21 (95% CI 0.13-0.34, P<0.0001)
• Ages ≥55: HR 0.18 (95% CI 0.08-0.38, P<0.0001)

Individuals whose BMIs were 35 to 39 kg/m2 or 40 kg/m2 and above also had similar results (P<0.0001 for both), although those in the lowest category (30 to 35 kg/m2) did not have significantly lower risks (P=0.1469).

The risks also were somewhat lower for gastric bypass and sleeve gastrectomy than with laparoscopic gastric banding, "but we caution against drawing firm conclusions concerning the comparative effectiveness of different procedures from a nonrandomized study because selection for different procedures might be associated with the underlying risk of developing diabetes," the researchers noted.

"Our findings ... suggest that bariatric surgery could be a highly effective method for prevention of diabetes in patients with severe obesity," Gulliford and colleagues concluded.

In an accompanying comment, Jacques M. Himpens, MD, of Saint Pierre University Hospital in Brussels wrote that although the results "bring us a step closer to confirming the effect of bariatric surgery on the incidence of de novo type 2 diabetes, many questions still remain unanswered and more evidence is needed to convince endocrinologists about the nature of this effect."

The study had a number of limitations, according to the authors, including the fact that controls didn't receive intensive nonsurgical management, there were differences in medication use, and the analysis relied on diabetes diagnoses from the administrative databank.