Gastric bypass leads to more significant and durable improvements in glycemic control than does sleeve gastrectomy or intensive medical therapy in moderately obese patients with type 2 diabetes, a prospective, randomized controlled trial has found.
Two years after the procedure, patients randomized to Roux-en-Y gastric bypass plus intensive medical therapy (IMT) had a mean HbA1c of 6.7 ± 1.2%, compared with 7.1 ± 0.8% for those who underwent sleeve gastrectomy and IMT, and 8.4 ± 2.3% for IMT alone, reported Dr Sangeeta R. Kashyap of the Cleveland Clinic and colleagues.
While both surgical procedures resulted in similar reductions in body weight, body mass index, and total body fat percentage at 24 months, gastric bypass resulted in the greatest absolute truncal fat reductions (–16% vs. –10%; P = .04), according to the findings, which were published online (Diabetes Care 2013 Feb. 25 [doi:10.2337/dc12-1596]).
The 2-year study enrolled a subset of 60 patients from the 1-year STAMPEDE trial, which evaluated the efficacy and safety of IMT alone – pharmacotherapy in conjunction with lifestyle interventions – or IMT combined with gastric bypass or sleeve gastrectomy. Of the 54 patients who completed the trial, the average age was 48.4 years, with a mean BMI of 36 kg/m2; most patients were taking at least three different diabetes medications.
The study extension examined the effects of the three treatment approaches on glucose control, pancreatic beta-cell function including insulin secretion and sensitivity, and body composition.
"Other long-term observational studies have documented greater relapse rates for glycemic control after gastric restrictive procedures such as sleeve gastrectomy, suggesting that surgical weight loss from enforced caloric restriction itself is insufficient to halt the disease," reported Dr Kashyap and colleagues. "Our results extend the findings from our initial 12-month report and suggest factors beyond weight loss that are specific to intestinal bypass patients help regulate glucose levels and restore pancreatic beta-cell function."
Gastric bypass was the only treatment to have any significant effects on pancreatic beta-cell function, with a median 5.8-fold (quartile 1: –7.00; quartile Q3: 11.29) increase in beta-cell function from baseline compared with only negligible increases for sleeve gastrectomy and IMT.
Researchers also observed a 2.7-fold (N = 9, 3.8 vs. 1.4; P < .001) increase in insulin sensitivity with gastric bypass among subjects not using insulin, compared with a 1.2-fold (N=10; 5.8 vs. 5.3) increase after sleeve gastrectomy, and no change in those randomized to IMT (2.6 vs. 2.4; P = NS).
"Bariatric surgery, particularly gastric bypass surgery, uniquely restores normal glucose tolerance and pancreatic [beta]-cell function, presumably by targeting the truncal fat that represents the core metabolic defect involved in diabetes pathogenesis," the researchers wrote.
Primary funding for the study came from Ethicon Endo-Surgery, with ancillary funding from the American Diabetes Association and the National Institutes of Health. The authors reported receiving research grants, consultations and honoraria from various companies and organizations, and one author received grants and honoraria from Ethicon Endo-Surgery as scientific advisory board member, consultant, and speaker.