Glucose and Insulin Response to GTT: A prospective comparison between Roux En Y Gastric Bypass, Vertical Sleeve Gastrectomy and Duodenal Switch at 1 year

Mitchell S Roslin, MD, FACS, Yuriy Dudiy, MD, Joanne Weiskopf, PA, Paresh C Shah, MD, FACS

Lenox Hill Hospital, North Shore-LIJ Health System

Background: Long term glucose and insulin homeostasis after bariatric surgery is still poorly understood. Reactive hypoglycemia after Gastric Bypass has been characterized by our group and others as having a strong hyperinsulinemia component which may contribute to weight regain thru food seeking behaviors. This prospective, non randomized IRB approved study is designed to assess the impact of 3 common stapling procedures (RYGB, VSG, DS) on glucose and insulin as measured by liquid and solid Glucose Tolerance Testing at 6,9, and 12 months post operatively. 38 patients were enrolled.

Methods: All patients enrolled had a Oral Glucose Tolerance Test (OGTT) as well as fasting glucose, insulin, HbA1c, c Peptide levels pre-operatively and at 6, 9, and 12 months post-operatively. The 9 month testing was performed with a solid meal. Ratios of Glucose and Insulin at 1hr/2hr and fasting/1hr were calculated. Statistical Analysis was performed with ANOVA and students paired T test.

Results: All groups were similar at baseline other than the DS group having a higher BMI. The results of GTT between liquid and solid challenges were not statistically different. All operations resulted in significant weight loss, reduction of fasting glucose, and improved insulin sensitivity. The rates of increase and the peak glucose and insulin levels after GTT were greatest in RYGB patients. The 1hr insulin level was higher than the pre-operative in this group. This was accompanied by a faster decline in glucose at 2 hrs. In comparison, the DS patients had a slower and lower total rise in glucose and insulin and the lowest HGBA1c levels (p<0.05). The VSG patients had results that were in between RYGB and DS, but were significantly different from RYGB as well.

Conclusions:The RYGB has a significantly dysfunctional insulin response to OGTT and creates hypoglycemia as a result. The VSG and DS preserve a more physiologic insulin response to OGTT without the supra-normal peaks. The DS response is substantially better than the VSG as well, suggesting that pyloric preservation, is not the only factor contributing to improved glucose homeostasis.

# of ptsBMIGlucose, fastingGlucose, 1hrGlucose, 2hrsInsulin, fastingInsulin, 1hrInsulin, 2hrs

6 mo1236.8±786.9±14165.3±87†88.9±513.6±176.25±45†‡15.7±23
9 mo1136.1±884.7±10138.6±64*†87.2±423.9±2.4†72.8±7411.4±9.5†
12 mo930.8±896.0±27165.5±10090.8±688.7±7.2°136.9±111*°10.8±6.8*

9 mo1335.0±1081.9±1397.9±32*83.0±2711.0±2340.0±4424.8±55
12 mo1033.8±585.8±20133.7±6282.7±4012.0±2656.9±43.0*40.2±62*‡

6 mo1338.2±777.9±18102.9±61†80.8±313.4±1.636.6±28†‡15±9
9 mo930.5±1479.8±1497.3±27†79.0±213.2±1.4†29.0±326.7±3.4†
12 mo828.0±783.0±23102.7±4268.7±243.1±1.1°31.1±15°6.5±5.2‡

* p < 0.05 RYGB versus VSG
† p < 0.05 RYGB versus DS
‡ p < 0.05 VSG versus DS
° p < 0.01 RYGB versus DS

Session: Podium Presentation

Program Number: S100

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