Bariatric Surgery Can Deliver Durable Diabetes Control: STAMPEDE

Marlene Busko

February 15, 2017

The final 5-year results of the Surgical Treatment and Medications Potentially Eradicate Diabetes Efficiently (STAMPEDE) trial of obese patients with uncontrolled type 2 diabetes showed that bariatric surgery plus intensive medical therapy was more effective than intensive medical therapy alone in decreasing or in some cases resolving hyperglycemia.

A previously reported, preliminary 5-year results from STAMPEDE were presented at the American College of Cardiology (ACC) 2016 Scientific Sessions in April. The final trial results, by Philip R Schauer, MD, from Cleveland Clinic, Ohio, and colleagues, were published in the February 15 issue of the New England Journal of Medicine.

"We're certainly not saying in this study that medications and lifestyle are not useful, but for some patients [with type 2 diabetes] who are refractory to lifestyle [changes] and medication and not controlled even with insulin, surgery is a very good option and has durable results out to 5 years," senior author Sangeeta R Kashyap, MD, Cleveland Clinic, told Medscape Medical News.

About one in four patients who had undergone Roux-en-Y gastric bypass or sleeve gastrectomy but only one in 20 patients who had received only intensive medical therapy attained the primary end point of HbA1c <6% at 5 years.

Moreover, the "beneficial effects of bariatric surgery on glycemic control were durable, even among patients with mild obesity (body mass index [BMI] of 27–34), which led to a sustained reduction in the use of diabetes and cardiovascular medications," Dr Schauer and colleagues report.

However, this was a small study, and a longer, larger multicenter study — which the group is planning to do — will be needed to confirm these findings and see whether the improved control of diabetes is tied to reduced risk of diabetes-related cardiovascular, renal, or ophthalmic disease.

Bariatric Surgery vs Medications Alone

STAMPEDE randomized 150 patients with uncontrolled type 2 diabetes (a mean HbA1c of 9.2%) and a BMI of 27 to 43 to receive intensive medical therapy alone, Roux-en-Y gastric bypass, or sleeve gastrectomy.

All patients met with clinicians every 3 months for 2 years and every 6 months for 3 years to receive adjustments in their intensive medical therapies with the goal of an HbA1c of 6% without unacceptable side effects.

A total of 134 patients (89%) completed the 5-year trial. On average, when they entered the study, the patients (66% women) had been 49 years old and had had diabetes for 8.4 years, and 44% required insulin.

A total of 49 patients (37%) had mild obesity (BMI <35) at study entry. "Much of diabetes occurs at a BMI of about 30," and these mildly obese patients tend to have greater visceral obesity, Dr Kashyap noted.

Better Glycemic Control, Risk vs Benefit Balancing Act

The primary end point of an HbA1c <6% was attained by significantly more patients in the gastric-bypass group than the medical-therapy group (29% vs 5%; P = .01) and in the sleeve-gastrectomy group than in the medical-therapy group (23% vs 5%; P = .03).

From baseline to 5 years, the mean HbA1c dropped from 9.3% to 7.3% in the gastric-bypass group and from 9.5% to 7.4% in the sleeve-gastrectomy group, but it fell only from 8.8% to 8.5% in the medical-therapy group.

The drop in HbA1c was similar in patients with a BMI <35 vs those with a BMI >35.

Importantly, the percentage of patients who required insulin dropped from 47% to 12% in the gastric-bypass group and from 45% to 11% in the sleeve-gastrectomy group, but dropped only from 53% to 40% in the medical-therapy group.

More than 88% of the patients who had surgery achieved good-to-acceptable glycemic control (mean HbA1c <7%).

Patients who underwent bariatric surgery had a more lasting weight loss. The mean BMI dropped from 37.0 to 28.9 in the gastric-bypass group and from 36.0 to 29.3 in the sleeve-gastrectomy group, but only from 36.4 to 34.0 in the medical-therapy group.

The surgery patients also had greater improvements in overall health and experienced less pain than other patients, based on their replies to the RAND 36-Item Health Survey.

"Quality of life is really dictated by weight loss," Dr Kashyap noted. By losing 20% of their body weight, patients have less pain in the lower back, hips, and knees from carrying excess weight. Moreover, "taking four shots of insulin a day and checking your blood sugar" is burdensome, but only 11% of patients in the surgery group still required insulin to control their glucose levels at 5 years, she pointed out.

Currently, insurance policies worldwide do not cover bariatric surgery for patients with a BMI of less than 35, Kashyap noted. "If someone has terrible diabetes and is on 100 units of insulin a day and poorly controlled and their BMI is 34, although we all know as clinicians that they would benefit, insurance will not cover it." This study supports the benefits of surgery in such patients.

However, bariatric surgery also entails risks of surgical complications, reoperation, anemia, and weight regain. "Those are the major things. It also a permanent change to the body, so surgery should not be taken lightly, and patients really need to talk about this decision with their doctors as well as their family members," Dr Kashyap cautioned.

Although the trial was too small to detect clinical differences between the two surgical procedures, gastric bypass was associated with more durable, larger weight loss and fewer diabetes medications than sleeve gastrectomy.

The study was funded by Ethicon Endo-Surgery, LifeScan, the Cleveland Clinic, and the National Institutes of Health. Dr Schauer reports grant support from Ethicon and the National Institutes of Health, nonfinancial support from Lifescan, and other support from the Cleveland Clinic during the conduct of the study; grant support from Medtronic and Paciria; personal fees from Ethicon, the Physicians Reviews of Surgery, the Springer Publishing Company, and the Medicines Company; personal fees and other support from Surgiquest and Global Academy; and other support from SE Healthcare Quality Consulting outside the submitted work. In addition, Dr. Schauer reports a pending patent related to medical devices for weight loss. Dr Kashyap reports grant support from Covidien and Janssen and grant support and personal fees from Ethicon Endo-Surgery outside the submitted work. Disclosures for the coauthors are listed in the paper.

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N Engl J Med. 2017;376:641-651. Abstract

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