The comparative effects of bariatric surgery on weight and type 2 diabetes

Background: Epidemiological evidence confirms that risk of developing type 2 diabetes is related to weight gain. Weight reduction is beneficial as relative risk is reduced to 0.13 for weight loss > 20 kg. This raises the question of effectiveness of bariatric surgery on 1) weight loss and 2) diabetes-related outcomes in morbidly obese patients. Methods: We reviewed the literature using Medline. Only 2 meta-analyses reporting on both outcomes were included, as well as 50 systematic reviews or primary studies. Results: Meta-analyses mainly based on case series data as well as controlled studies confirm that bariatric surgery is highly effective in obtaining weight reduction in morbidly obese patients up to 60% of the excess weight, along with resolution of preoperative diabetes in more than 75% of cases. Among bariatric surgery techniques, malabsorptive procedures (biliopancreatic diversion and gastric bypass) appear to be more effective on both outcomes than restrictive procedures (gastroplasty and gastric banding). Conclusion: Even if more studies are needed to confirm current evidence, bariatric surgery is effective for controlling diabetes. It appears as an efficient strategy from economic modeling due to savings from reduction in diabetes-related costs.