Clinical Outcomes of Metabolic Surgery: Efficacy of Glycemic Control, Weight Loss, and Remission of Diabetes

Abstract

Since the 2007 Diabetes Surgery Summit in Rome, Italy, and the subsequent publishing of the world's first guidelines for the surgical treatment of type 2 diabetes (T2D), much new evidence regarding the efficacy and safety of metabolic surgery has emerged. Additional observational cohort studies support the superior effects of surgery over medical treatment with respect to glycemic control, weight loss, and even reduction in mortality and microvascular complications associated with T2D. Furthermore, new safety data suggest that the perioperative morbidity and mortality of metabolic surgery (5% and 0.3%, respectively) are now similar to that of common low-risk procedures, such as cholecystectomy and hysterectomy. The largest advance, however, has been the completion of 11 randomized controlled trials from around the globe that compare surgery with medical treatment of T2D. These studies with follow-up duration of 1-5 years involve nearly 800 patients without surgical mortality and with major complication rates of less than 5% and a reoperation rate of 8%. All but 1 of the 11 randomized controlled trials have shown the superiority of surgery over medical management at achieving remission or glycemic improvement. Surgery was also superior to medical treatment with respect to improving cardiovascular risk factors, such as weight loss and dyslipidemia, while reducing medication burden. This new efficacy and safety evidence should help guide physicians across the globe to the appropriate use of surgery as an effective treatment for patients suffering from T2D and obesity.

Figure 1

Common metabolic procedures and their frequency of use. Reprinted with permission from Cleveland Clinic Foundation.

Figure 2

Forest plot of mean differences (MDs) of %HbA_1c serum levels after bariatric/metabolic surgery compared with medical/lifestyle treatments in published RCTs. Data are arranged in order of ascending time to follow-up. Study duration and HbA_1c end point thresholds are shown in brackets in column 1, where “off meds” indicates a threshold achieved off all diabetes medications; otherwise, end points represent HbA_1c thresholds achieved with or without such medications. Negative MDs denote lower HbA_1c levels following surgery than medical/lifestyle treatment. MDs for each study are shown as the MD with its 95% CI.

Figure 3

Change in HbA_1c after LAGB, RYGB, SG, and BPD in 11 RCTs.

Figure 4

Change in HbA_1c after surgical vs. medical treatment of T2D in the studies by Schauer et al. (31) (A), Mingrone et al. (32) (B), Ikramuddin et al. (34) (C), and Courcoulas et al. (39) (D). LWLI, lifestyle weight-loss intervention; y, years. Reprinted with permission from the four studies.

Figure 5

Other secondary end points favoring surgery over medical treatment. A: Weight loss in the study by Mingrone et al. (33). *From ANOVA comparison. B: Change in HDL (33). †From nonparametric tests. C: Change in medications in the study by Schauer et al. (31). D: Change in quality of life (31). *P < 0.05 for the comparison between the gastric bypass group and the medical therapy group; †P < 0.05 for the comparison between the sleeve gastrectomy group and the medical therapy group. Reprinted with permission from the two studies.

Figure 6

Remission at 5 years in the study by Mingrone et al. (33).