Research Clinical

Obesity Surgery

, 19:1550

First online:

Plasma Glucose and Insulin Regulation Is Abnormal Following Gastric Bypass Surgery with or Without Neuroglycopenia

  • Sun H. KimAffiliated withDepartment of Medicine, Stanford University Medical Center Email author 
  • , Teresa C. LiuAffiliated withDepartment of Medicine, Stanford University Medical Center
  • , Fahim AbbasiAffiliated withDepartment of Medicine, Stanford University Medical Center
  • , Cindy LamendolaAffiliated withDepartment of Medicine, Stanford University Medical Center
  • , John M. MortonAffiliated withDepartment of Surgery, Stanford University Medical Center
  • , Gerald M. ReavenAffiliated withDepartment of Medicine, Stanford University Medical Center
  • , Tracey L. McLaughlinAffiliated withDepartment of Medicine, Stanford University Medical Center

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Abstract

Background

Enhanced insulin sensitivity is commonly seen following Roux-en-Y gastric bypass surgery (RYGB) whereas symptomatic hypoglycemia post-RYGB seems to occur infrequently. It is unclear how different plasma glucose and insulin responses are in patients with symptomatic hypoglycemia (SX-RYGB) versus those who remain asymptomatic (ASX-RYGB), nor when compared with non-surgical controls with varying degrees of insulin sensitivity.

Methods

Plasma glucose and insulin concentrations were determined following a 75-g oral glucose challenge in five groups: symptomatic and asymptomatic patients following RYGB (n = 9 each) and overweight/obese controls, divided into three subgroups (n = 30 each) on the basis of degree of insulin sensitivity measured by the insulin suppression test.

Results

SX-RYGB group had higher 30-min glucose after oral glucose compared with the ASX-RYGB group (p = 0.04). The two groups did not differ in peak glucose and insulin concentrations, nadir glucose concentration, or insulin-to-glucose ratio 30 min after oral glucose. These values were significantly different from the three control groups, and peak insulin concentrations post-RYGB were increased at every degree of insulin sensitivity as compared with the control groups.

Conclusions

Plasma glucose and insulin responses to oral glucose in patients with symptomatic hypoglycemia post-RYGB are minimally different when compared to individuals who remain asymptomatic, and both groups demonstrate hyperinsulinemia out of proportion to their degree of insulin sensitivity.

Keywords

Gastric bypass Hypoglycemia Obesity Hyperinsulinism Insulin resistance