Bariatric surgery leads to short-term improved glycemic control and weight loss in moderately obese diabetics

Bariatric surgery in diabetic patients with a body mass index of 30 to 35 kg/m² is associated with more short-term weight loss and better intermediate outcomes than nonsurgical treatments, but data on long-term effects are limited, a review found.

Researchers reviewed 32 surgical studies and 11 systematic reviews on nonsurgical treatments, as well as 11 large nonsurgical studies published after those reviews, for data on weight loss, metabolic outcomes and adverse events. Results appeared in the June 5 Journal of the American Medical Association.

In three randomized clinical trials totaling 290 subjects, surgery was associated with greater weight loss (range, 14.4 to 24 kg) and glycemic control (range, 0.9 to 1.43 point improvements in hemoglobin A1c levels) during one to two years of follow-up compared to nonsurgical treatment. Indirect comparisons of evidence from observational studies of about 600 bariatric procedures and meta-analyses of more than 300 randomized, controlled trials of nonsurgical therapies support this finding as far out as two years of follow-up.

However, the authors wrote, there are no robust surgical data beyond five years of follow-up on outcomes such as glucose control and macrovascular and microvascular outcomes. Randomized controlled trial data on nonsurgical therapies show benefits at 10 years of follow-up or more.

In 14 studies reviewed for patient safety, surgeon-reported adverse events were low, but data were from select centers and surgeons. Only one death was reported in a patient receiving gastric banding with complications of a gastric perforation. Cardiovascular, respiratory, gastrointestinal and metabolic adverse events were relatively rare. Other complications included infections or seroma, incisional hernias, stricture, anastomotic leaks, and ulcers. Several complications specific to gastric banding were reported: band slippage in 3% of 361 patients, port or tube problems in about 1.9% of 462 patients, band removal in 3.3% of 210 patients and pouch dilation in 5.4% of 240 patients.

Researchers noted that these studies may represent best-case outcomes, since they were often small-population and single-site reports without long-term follow up.

“In contrast, behavior and medication interventions have been studied extensively in a wide variety of clinical settings; several large, long-term randomized clinical trials have found improved [hemoglobin]A1c levels for up to 10 years,” researchers wrote. “Therefore, the evidence for longer-term control of glucose in patients with diabetes is stronger for behavioral and medication therapies than for surgery.”