Mechanism for improved insulin sensitivity after gastric bypass surgery.
BACKGROUND
Surgical treatments of obesity have been shown to induce rapid and prolonged improvements in insulin sensitivity.


OBJECTIVE
The aim of the study was to investigate the effects of gastric bypass surgery and the mechanisms that explain the improvement in insulin sensitivity.


METHODS
We performed a cross-sectional, nonrandomized, controlled study.


METHODS
This study was conducted jointly between the Departments of Exercise Science and Physiology at East Carolina University in Greenville, North Carolina.


METHODS
Subjects were recruited into four groups: 1) lean [body mass index (BMI) < 25 kg/m(2); n = 93]; 2) weight-matched (BMI = 25 to 35 kg/m(2); n = 310); 3) morbidly obese (BMI > 35 kg/m(2); n = 43); and 4) postsurgery patients (BMI approximately 30 kg/m(2); n = 40). Postsurgery patients were weight stable 1 yr after surgery.


METHODS
Whole-body insulin sensitivity, muscle glucose transport, and muscle insulin signaling were assessed.


RESULTS
Postsurgery subjects had insulin sensitivity index values that were similar to the lean and higher than morbidly obese and weight-matched control subjects. Glucose transport was higher in the postsurgery vs. morbidly obese and weight-matched groups. IRS1-pSer(312) in the postsurgery group was lower than morbidly obese and weight-matched groups. Inhibitor kappaBalpha was higher in the postsurgery vs. the morbidly obese and weight-matched controls, indicating reduced inhibitor of kappaB kinase beta activity.


CONCLUSIONS
Insulin sensitivity and glucose transport are greater in the postsurgery patients than predicted from the weight-matched group, suggesting that improved insulin sensitivity after bypass is due to something other than, or in addition to, weight loss. Improved insulin sensitivity is related to reduced inhibitor of kappaB kinase beta activity and enhanced insulin signaling in muscle.
Bikman
Benjamin T
BT
The Metabolic Institute for the Study of Diabetes and Obesity, East Carolina University, 6N98 600 Moye Boulevard, Greenville, North Carolina 27834, USA.
Zheng
Donghai
D
Pories
Walter J
WJ
Chapman
William
W
Pender
John R
JR
Bowden
Rita C
RC
Reed
Melissa A
MA
Cortright
Ronald N
RN
Tapscott
Edward B
EB
Houmard
Joseph A
JA
Tanner
Charles J
CJ
Lee
Jihyun
J
Dohm
G Lynis
GL