Bariatric surgery for weight loss and glycemic control in nonmorbidly obese adults with diabetes: a systematic review.

Maggard-Gibbons M, Maglione M, Livhits M et al.
JAMA. 2013 Jun 5;309(21):2250-61. doi: 10.1001/jama.2013.4851

Background

In morbidly obese patients (BMI>35) bariatric surgery such as laparoscopic adjustable gastric banding and Roux-en-Y gastric bypass have yielded better glucose control and more weight loss after 1 or 2 years than non-surgical therapy [1,2]. Metabolic changes shortly after surgery suggest that part of the mechanism may be independent of weight loss [3-5].
There is controversy on whether bariatric surgical procedures should be recommended in persons with BMI 30-35 with obesity-related comorbidities. The authors therefore conducted a systematic review of the relative benefits and risks associated with surgical and non-surgical therapies to treat diabetes or impaired glucose tolerance in patients with a BMI of 30-35 [6,7].

Main results

• Different direct comparisons of surgical vs non-surgical interventions were too diverse methodologically and clinically to justify statistical pooling. Overall, they showed that patients who underwent bariatric surgery showed greater and more durable weight loss and decrease of metabolic syndrome than patients who received medical therapy.
• Small observational cohort studies also showed greater weight loss, a decrease in mean BMI and an improvement in HbA1c concentration in surgically treated patients as compared to patients receiving routine medical management for diabetes and weight control.
• In comparisons of surgical procedures, gastric bypass resulted in more weight loss after 1 year than sleeve gastrectomy. Lower fasting glucose was achieved in most patients receiving gastric bypass in one study, whereas another study showed similar results for gastric bypass and sleeve gastrectomy, although the latter group needed more medication for diabetes control.
  Gastric bypass resulted in more weight loss and better control of diabetes than did laparoscopic gastric banding.
  Another small cohort  study showed better diabetic control 1 year after biliopancreatic diversion than in patients who underwent gastric bypass surgery.
• Long-term follow-up (10-20 years) of non-surgical interventions have been published, but no such data are available for surgical procedures as yet. Overall, achieved weight loss after nonsurgical treatment did not persist in the long run, while reduced diabetes incidence did.

Conclusion

Current available evidence suggests that bariatric surgery is associated with more weight loss and better glucose control on the short term than nonsurgical therapy in patients with a BMI of 30-35 and diabetes. Long-term data on the benefits and risks of surgical approaches is needed to determine the preferred treatment of diabetes in this target population. 

Editorial comment [8]

Considering the considerable proportion of US adults with a BMI of 30-35, a part of whom have diabetes type 2, any proposal to treat this large group of patients surgically needs careful evaluation, as they will have substantial implications on the health care system.
Another study published in this issue of JAMA [9] found a favourable metabolic outcome in surgically treated patients (BMI 30-35, diabetes type 2) as compared to patients receiving lifestyle-medical management only. However, gastric bypass surgery was followed by a higher complication rate.
The overall health benefit of bariatric surgery should be considered. Furthermore, long-term safety needs to be established as well as the prevalence and severity of complications in the long run, and the diabetic recurrence rate. Economic aspects of bariatric surgery must also be evaluated.
The difficulties encountered by Maggard-Gibbons et al to perform a systematic review prove that more well-designed, randomised trials are needed to reveal what is the optimal approach for treatment of obesity and diabetes.

References

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