STAMPEDE Trial: Bariatric Surgery Beats Medical Management for Obese Patients with Diabetes

For obese individuals with type 2 diabetes mellitus (DM), better glycemic control often occurs when body mass index (BMI) drops. Achieving long-term weight loss, however, is very difficult. Despite the growing popularity of the procedure in this patient population, the literature lacks rigorous examination of the effectiveness of bariatric surgery compared to intensive medical therapy for optimizing glycemic control in patients with type 2 diabetes.

At the American College of Cardiology 2014 Scientific Session, held in Washington, DC, the Cleveland Clinic’s Sangeeta Kashyap, MD, principal investigator for the STAMPEDE trial, presented good results for surgical patients at the one-year mark.

In a study of 150 moderately to severely obese patients with type 2 diabetes (BMI 27-43 kg/m² and HbA1c >7.0%), subjects were randomized 1:1:1 to receive intensive medical therapy alone, medical therapy plus gastric bypass (the Roux-en-Y procedure), or medical therapy plus sleeve gastrectomy. At the 12-month mark, STAMPEDE researchers reported 93% retention, with the population for primary analysis being 41, 50, and 49 subjects for the three arms respectively.

The study population was relatively young (mean age slightly less than age 50), had poor glycemic control (mean HbA1c 8.9, 9.3, and 9.5 among the three groups), and consisted of slightly more than 50% females. Mean body mass index for study subjects was 37. Most patients were on more than three diabetes medications, and nearly half were receiving insulin.

The primary endpoint was defined as the success rate of achieving HbA1c less than or equal to 6%. Secondary endpoints, in addition to safety and adverse events, included change in medications, fasting plasma glucose (FPG), BMI, lipids, blood pressure, or highly-sensitive C-reactive protein. Intensive medical care, delivered to all treatment arms, followed the ADA clinical care guidelines. In addition to optimal medical management, this included diet and lifestyle counseling, frequent home glucose monitoring, and regularly scheduled visits with physicians and allied health professionals.

In comparing both gastric bypass and sleeve gastrectomy against medical therapy, both surgical procedures outperformed medical therapy alone in all primary and secondary outcomes. All measures reached statistical significance. Notably, 42% of the bypass patients and 27% of the sleeve patients achieved HbA1c of less than or equal to 6% with no diabetes medications. The large majority (92 to 96%) of the surgical treatment arms no longer required insulin at 12 months post surgery, while just over 40% of the medical management patients were still using insulin. A total of 44 study participants in the surgical arms were taking no cardiovascular medications at one year after study enrollment, as compared with zero medical therapy patients at 12 months (P< .001 for both arms). At the beginning of the study period, just five of the surgical patients had been able to avoid cardiovascular medications.

As expected, BMI dropped nine to ten points in surgery recipients, but losses of almost two points were also seen in the medical therapy arm. Quality of life indices were also higher in surgical patients.

Study subjects, especially bypass recipients, experienced more adverse events then those undergoing medical therapy, but the study authors report that the complication rate was similar to other observational studies with gastric bypass, and no long-term morbidity was reported. Four of the Roux-en-Y patients required reoperation for anastomotic ulcer.

Study limitations include small sample size and single site design, as well as short follow-up period. The authors note that subjects will be followed out to four years, and recommended larger multisite studies to validate findings.

In a press conference following the morning’s Late-Breaking Clinical Trials session, Amit Khera, MD, University of Texas Southwestern Medical Center, remarked that long-term follow-up of these patients will show whether improved glycemic control from gastric bypass surgery will have a durable effect. He said follow-up care will also help clarify the outcome for patients with type 2 diabetes and only moderate obesity who receive gastric bypass.

He also noted the importance of gathering quality of life data for these patients, and remarked on the significant increases seen in quality of life for surgery patients, even taking into consideration the burden of surgery recovery.