Diabetes and Weight in Comparative Studies of Bariatric Surgery vs Conventional Medical Therapy: A Systematic Review and Meta-Analysis

Abstract

We performed a meta-analysis of weight loss and remission of type 2 diabetes mellitus (T2DM) evaluated in randomized controlled trials (RCTs) and observational studies of bariatric surgery vs conventional medical therapy. English articles published through June 10, 2013 that compared bariatric surgery with conventional therapy and included T2DM endpoints with ≥12-month follow-up were systematically reviewed. Body mass index (BMI, in kilogram per square meter), glycated hemoglobin (HbA1C, in degree), and fasting plasma glucose (FPG, in milligram per deciliter) were analyzed by calculating weighted mean differences (WMDs) and pooled standardized mean differences and associated 95 % confidence intervals (95 % CI). Aggregated T2DM remission event data were analyzed by calculating the pooled odds ratio (POR) and 95 % CI. Random effects assumptions were applied throughout; I2 ≥ 75.0 % was considered indicative of significant heterogeneity. Systematic review identified 512 articles: 47 duplicates were removed, 446 failed inclusion criteria (i.e., n < 10 per arm, animal studies, reviews, case reports, abstracts, and kin studies). Of 19 eligible articles, two not focused on diagnosed T2DM and one with insufficient T2DM data were excluded. In the final 16 included papers, 3,076 patients (mean BMI, 40.9; age, 47.0; 72.0 % female) underwent bariatric surgery; 3,055 (39.4; 48.6, 69.0 %) received conventional or no weight-loss therapy. In bariatric surgery vs conventional therapy groups, the mean 17.3 ± 5.7 month BMI WMD was 8.3 (7.0, 9.6; p < 0.001; I2 = 91.8), HbA1C was 1.1 (0.6, 1.6; p < 0.001; I2 = 91.9), and FPG, 24.9 (15.9, 33.9; p < 0.001; I2 = 84.8), with significant differences favoring surgery. The overall T2DM remission rate for surgery vs conventional group was 63.5 vs 15.6 % (p < 0.001). The Peto summary POR was 9.8 (6.1, 15.9); inverse variance summary POR was 15.8 (7.9, 31.4). Of the included studies, 94.0 % demonstrated a significant statistical advantage favoring surgery. In a meta-analysis of 16 studies (5 RCTs) with 6,131 patients and mean 17.3-month follow-up, bariatric surgery was significantly more effective than conventional medical therapy in achieving weight loss, HbA1C and FPG reduction, and diabetes remission. The odds of bariatric surgery patients reaching T2DM remission ranged from 9.8 to 15.8 times the odds of patients treated with conventional therapy.Electronic supplementary materialThe online version of this article (doi:10.1007/s11695-013-1160-3) contains supplementary material, which is available to authorized users.

Costs and outcomes of increasing access to bariatric surgery for obesity: cohort study and cost-effectiveness analysis using electronic health records

“…About one-third of all participants who received bariatric surgery were diabetic, indicating positive selection of diabetes patients for this intervention, consistent with current policy recommendations that bariatric surgery should be utilised in the management of obesity-associated comorbidity. Changes in mean HbA 1c in our study were similar to those reported in previous studies, 72 but rates of diabetes remission after surgery reported in the present study were generally lower than those noted in published reviews, which ranged from 59% to 92%. 6,32,70 However, case definitions have varied.…”

“…One incorporated RCTs and controlled cohorts both separately and together into random-effect meta-analyses. 72 Combining the 11 observational studies and five RCTs together gave a pooled OR of 9.8 (95% CI 6.1 to 15.9). The other used narrative analysis to discuss the results of five RCTs, four of which matched the former review.…”

Type 2 Diabetes Mellitus- Disease, Diagnosis and Treatment

“…The diabetic patients with BMI > 35 kg/m 2 are currently eligible for bariatric surgery, according to the NIH Consensus Criteria for bariatric surgery. Recent meta-analyses of 16 studies with 6131 patients and mean 17.3-month follow-up have found bariatric surgery to be superior to conventional medical therapy in achieving significant weight loss, HbA1c and fasting plasma glucose reduction and diabetes remission [51]. Thus, bariatric surgery has been accepted as the most effective treatment along with significant metabolic benefits for patients with T2DM and BMI > 35 kg/ m 2 [52].…”

For a Step Change to Curb the Obesity Epidemic

“…Bariatric surgery has emerged as the first (and, so far, only) technology associated with significant success against severe obesity [29][30][31] and its associated comorbidities [32] for a large proportion of treated patients. The procedure has demonstrated significant cost savings and return on investment for patients with class 3 obesity (i.e., BMI C40.0 patients) [33][34][35][36][37][38][39][40][41] and may be of benefit for other categories of patients [19].…”