Surgery Tops Usual Care in Obese Diabetics in 15-Year Study

Marlene Busko

June 11, 2014

In the longest study to date comparing bariatric surgery with usual care in obese, diabetic patients, surgery was associated with greater weight loss and diabetes remission and fewer macrovascular and microvascular complications than medical care.

Fifteen years after undergoing bariatric surgery, 30% of patients no longer had diabetes, but only 7% of patients who received usual care were in diabetes remission.

These long-term findings from the Swedish Obese Subjects (SOS) prospective, matched-cohort study by Lars Sjöström, MD, from Sahlgrenska University Hospital, in Gothenburg, Sweden, and colleagues are published in the June 11 special diabetes-themed issue of the Journal of the American Medical Association, timed to coincide with the American Diabetes Association (ADA) 2014 Scientific Sessions, which start in San Francisco on Friday.

"Diet and lifestyle measures will always be the cornerstone of diabetes therapy, [but] bariatric surgery is an option for patients who are unable to lose sufficient weight with diet and exercise and who are willing to accept the risks of bariatric surgery and comply with the lifestyle changes required after bariatric surgery," Anne R. Cappola, MD, from the Perelman School of Medicine at the University of Pennsylvania, in Philadelphia, told Medscape Medical News.

Overall, the study findings "validate the expectations of bariatric-surgery–associated weight loss and provide concrete numbers to cite," says Dr. Cappola, who is coauthor of an editorial that accompanies the article and also a JAMA associate editor.

They also show that "obese diabetics whose diabetes was of shorter duration or who had the greatest weight loss between the time of surgery and two years [later] were the most likely to have a sustained remission at 15 years," she pointed out. "These patients likely had bariatric surgery before the failure of the insulin-producing cells of the pancreas was irreversible."

Long-Term Diabetes Remission, Reduction in Complications

The SOS study enrolled 4047 obese patients in Sweden between 1987 and 2001. The current analysis looked at those who had diabetes at baseline: 260 patients who then received usual medical care and 343 patients who underwent bariatric surgery—vertical banded gastroplasty (227 patients), nonadjustable or adjustable banding (61 patients), or Roux-en-Y gastric bypass (55 patients).

The patients had a mean age of about 50, a mean body mass index (BMI) of about 41, and about 60% were women. They had had diabetes for about 3 years.

The researchers tracked microvascular complications of the kidney, eyes, and peripheral nerves and macrovascular complications—coronary heart disease, heart failure, stroke, and peripheral arterial disease—after a median of about 17 years.

Diabetes remission was defined as having a blood glucose level below 110 mg/dL and not taking antidiabetic medication.

Bariatric surgery was associated with higher diabetes-remission rates and weight loss compared with usual care, although these rates declined over time in both groups.

Outcomes in SOS Subjects with Diabetes, Control vs Bariatric-Surgery Groups

Outcome Control group Bariatric surgery group
Diabetes remission at 2 y (%) 16 72
Diabetes remission at 15 y (%) 7 30
Weight loss at 2 y (kg) -3 -26.3
Weight loss at 10 y (kg) -4.4 -22.5

Bariatric surgery was also associated with a significantly decreased risk for microvascular and macrovascular complications (hazard ratios, 0.43 and 0.74, respectively).

Study limitations include the lack of randomization and a significant loss to follow-up by 15 years, and the findings require confirmation in randomized trials, the researchers stress.

Same Outcomes With Different Surgery Types?

Another constraint is that the types of bariatric surgery being performed today are somewhat different from the procedures used in SOS.

For example, "a worldwide survey in 2011 [reported] that 47% received gastric bypass, 18% lap band, 28% sleeve gastrectomy, and vertical banded gastroplasty represented less than 1%," Dr. Cappola noted.

However, "all of the surgical procedures, regardless of type, had a high success rate for remission," she added. "The magnitudes of the differences found between the bariatric-surgery and control groups suggest that additional refinements in study design are unlikely to negate these results," she and her coeditorialist write.

Additional follow-up of newer studies is required to answer the question of which bariatric procedure is best for inducing long-term remission of diabetes, but those data will not be available for another 5 to 10 years, Dr. Cappola concluded.

This study was supported by grants from the Swedish Research Council, the Swedish Foundation for Strategic Research (to the Sahlgrenska Center for Cardiovascular and Metabolic Research), the Swedish federal government, Diabetesfonden, and the VINNOVA-VINNMER program. The SOS study has previously been supported by grants to authors from Hoffmann–La Roche, AstraZeneca, Cederroth, Sanofi, and Johnson & Johnson. Dr. Sjöström reports receiving lecture fees from AstraZeneca and Johnson & Johnson and providing an expert statement on drug effects and weight loss effects on obesity for AstraZeneca. Disclosures for the coauthors are listed in the article. Dr. Cappola reports serving as a consultant for Novartis and MannKind. Her coauthor reports no relevant financial relationships.

JAMA. 2014;311: 2297-2304, 2277-2278. Abstract, Editorial

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