The mechanism of diabetes control after gastrointestinal bypass surgery reveals a role of the proximal small intestine in the pathophysiology of type 2 diabetes.
BACKGROUND
Most patients who undergo Roux-en-Y gastric bypass (RYGB) experience rapid resolution of type 2 diabetes. Prior studies indicate that this results from more than gastric restriction and weight loss, implicating the rearranged intestine as a primary mediator. It is unclear, however, if diabetes improves because of enhanced delivery of nutrients to the distal intestine and increased secretion of hindgut signals that improve glucose homeostasis, or because of altered signals from the excluded segment of proximal intestine. We sought to distinguish between these two mechanisms.


METHODS
Goto-Kakizaki (GK) type 2 diabetic rats underwent duodenal-jejunal bypass (DJB), a stomach-preserving RYGB that excludes the proximal intestine, or a gastrojejunostomy (GJ), which creates a shortcut for ingested nutrients without bypassing any intestine. Controls were pair-fed (PF) sham-operated and untreated GK rats. Rats that had undergone GJ were then reoperated to exclude the proximal intestine; and conversely, duodenal passage was restored in rats that had undergone DJB. Oral glucose tolerance (OGTT), food intake, body weight, and intestinal nutrient absorption were measured.


RESULTS
There were no differences in food intake, body weight, or nutrient absorption among surgical groups. DJB-treated rats had markedly better oral glucose tolerance compared with all control groups as shown by lower peak and area-under-the-curve glucose values (P < 0.001 for both). GJ did not affect glucose homeostasis, but exclusion of duodenal nutrient passage in reoperated GJ rats significantly improved glucose tolerance. Conversely, restoration of duodenal passage in DJB rats reestablished impaired glucose tolerance.


CONCLUSIONS
This study shows that bypassing a short segment of proximal intestine directly ameliorates type 2 diabetes, independently of effects on food intake, body weight, malabsorption, or nutrient delivery to the hindgut. These findings suggest that a proximal intestinal bypass could be considered for diabetes treatment and that potentially undiscovered factors from the proximal bowel might contribute to the pathophysiology of type 2 diabetes.
Rubino
Francesco
F
IRCAD-European Institute of Telesurgery, University Louis Pasteur, Strasbourg, France. f.rubino@lycos.com
Forgione
Antonello
A
Cummings
David E
DE
Vix
Michel
M
Gnuli
Donatella
D
Mingrone
Geltrude
G
Castagneto
Marco
M
Marescaux
Jacques
J
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000503:physiopathology* / Q000517:prevention & control*; D004195:Disease Models, Animal; D005230:Fatty Acids, Nonesterified / Q000097:blood; D015390:Gastric Bypass; D005951:Glucose Tolerance Test; D007328:Insulin / Q000097:blood; D007408:Intestinal Absorption / Q000502:physiology; D007421:Intestine, Small / Q000378:metabolism / Q000503:physiopathology*; D008297:Male; D009767:Obesity, Morbid / Q000601:surgery*; D011184:Postoperative Period; D051381:Rats; D017208:Rats, Wistar; D016896:Treatment Outcome; D015430:Weight Gain
D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007328:Insulin