Obesity affects more than one-third of adults in the U.S., greatly increasing the risk of type 2 diabetes mellitus (T2DM), one of the most challenging contemporary threats to public health. Uncontrolled diabetes leads to macrovascular and microvascular complications, including myocardial infarction, stroke, blindness, neuropathy, and renal failure in many patients.

In the last few years, efforts have been made to change the conversation from thinking of bariatric surgery as a means of achieving weight loss, and instead to think of it more as metabolic surgery and comorbid condition resolution. This effort has been reinforced by recent data from the STAMPEDE trial (Surgical Therapy And Medications Potentially Eradicate Diabetes Efficiently).¹ This randomized, controlled, single-center study compared intensive medical therapy with surgical treatment as a means of improving glycemic control in obese T2DM patients.

STAMPEDE for Uncontrolled Diabetes

Investigators screened 218 patients at the Cleveland Clinic and assigned 150 eligible patients to undergo intensive medical therapy alone or intensive medical therapy plus either Roux-en-Y gastric bypass or sleeve gastrectomy. Bariatric procedures were performed laparoscopically by a single surgeon. Gastric bypass consisted of the creation of a 15- to 20-ml gastric pouch, a 150-cm Roux limb, and a 50-cm biliopancreatic limb. Sleeve gastrectomy involved a gastric-volume reduction of 75-80 percent by resecting the stomach alongside a 30-Fr endoscope beginning 3 cm from the pylorus and ending at the angle of His.

The study population had moderate to severe obesity (BMI >30 kg/m²) and relatively advanced, poorly controlled diabetes, including many patients with diabetes-related coexisting illnesses or evidence of end-organ damage. Patients had an average disease duration of longer than eight years and a mean baseline glycated hemoglobin (A1c) level of 8.9-9.5 percent. At baseline, study participants were receiving, on average, nearly three antidiabetic agents, including relatively high use of insulin (44 percent of patients) or other injectable therapies (14 percent).

The primary endpoint was the proportion of patients with an A1c level of 6 percent or less (with or without diabetes medications) at 12 months after randomization (average baseline level was 9.2±1.5 percent). Patients undergoing surgery were significantly more likely to achieve an A1c level of 6 percent or less 12 months after randomization than patients receiving intensive medical therapy alone.

According to Philip Schauer, MD, first author of the study, "Interestingly, all of the gastric bypass patients who reached an A1c of 6% or less did so without any medication—in other words, they were weaned off all of their antidiabetic medications, including insulin, to reach this target. This is as close to a definition of remission that you can get."

Similarly, lipid-lowering drugs were required at baseline for the vast majority of patients, but after gastric bypass and sleeve gastrectomy, use declined to 27 percent and 39 percent respectively after 12 months, compared to 92 percent for medical therapy (p < 0.001).

For other clinical and laboratory outcomes, surgical intervention was superior to intensive drug therapy in regards to weight loss, decreased BMI, reduced prevalence of metabolic syndrome, lowered rates of hyperinsulinemia, and insulin resistance (Figure 2). A significant decrease in triglycerides occurred at 12 months after gastric bypass but not after sleeve gastrectomy, as compared with medical therapy. There was a marked increase in high-density lipoprotein cholesterol, as well as a significant decrease in high-sensitivity C-reactive protein level after the two surgical procedures compared to intensive medical therapy alone.

The authors noted that observational studies of bariatric procedures have shown rates of remission of T2DM of 55-95%, although they added that resolution was often determined without biochemical evidence (levels of glycated hemoglobin or fasting plasma glucose) or with the use of more liberal definitions of remission. The inclusion of patients with more advanced T2DM in the STAMPEDE trial probably explains the lower observed rate of diabetes remission.

Reference

1. Schauer PR, Kashyap SR, Wolski K, et al. N Engl J Med. 2012;366:1567-76.

To listen to an interview with Philip Schauer, MD, about bariatric surgery for diabetes treatment, visit youtube.cswnews.org. The interview was conducted by Steven Nissen, MD.

Keywords: Bariatric Surgery, Insulin, Gastric Bypass, Weight Loss, Diabetes Mellitus, Type 2, Glycated Hemoglobin A, Public Health, C-Reactive Protein, Gastrectomy, Obesity, Cholesterol, HDL, Triglycerides

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