First-phase insulin secretion restoration and differential response to glucose load depending on the route of administration in type 2 diabetic subjects after bariatric surgery.
OBJECTIVE
The purpose of this study was to elucidate the mechanisms of diabetes reversibility after malabsorptive bariatric surgery.


METHODS
Peripheral insulin sensitivity and beta-cell function after either intravenous (IVGTT) or oral glucose tolerance (OGTT) tests and minimal model analysis were assessed in nine obese, type 2 diabetic subjects before and 1 month after biliopancreatic diversion and compared with those in six normal-weight control subjects. Insulin-dependent whole-body glucose disposal was measured by the euglycemic clamp, and glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) were also measured.


RESULTS
The first phase of insulin secretion after the IVGTT was fully normalized after the operation. The disposition index from OGTT data was increased about 10-fold and became similar to the values found in control subjects, and the disposition index from IVGTT data increased about 3.5-fold, similarly to what happened after the euglycemic clamp. The area under the curve (AUC) for GIP decreased about four times (from 3,000 +/- 816 to 577 +/- 155 pmol x l(-1) x min, P < 0.05). On the contrary, the AUC for GLP1 almost tripled (from 150.4 +/- 24.4 to 424.4 +/- 64.3 pmol x l(-1) . min, P < 0.001). No significant correlation was found between GIP or GLP1 percent changes and modification of the sensitivity indexes independently of the route of glucose administration.


CONCLUSIONS
Restoration of the first-phase insulin secretion and normalization of insulin sensitivity in type 2 diabetic subjects after malabsorptive bariatric surgery seem to be related to the reduction of the effect of some intestinal factor(s) resulting from intestinal bypass.
Salinari
Serenella
S
Department of Systems Analysis and Informatics, University of Rome La Sapienza, Rome, Italy. salinari@dis.uniroma1.it.
Bertuzzi
Alessandro
A
Asnaghi
Simone
S
Guidone
Caterina
C
Manco
Melania
M
Mingrone
Geltrude
G
D000328:Adult; D050110:Bariatric Surgery; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism* / Q000601:surgery*; D004333:Drug Administration Routes; D005260:Female; D005749:Gastric Inhibitory Polypeptide / Q000378:metabolism; D052216:Glucagon-Like Peptide 1 / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical
D007328:Insulin; D005749:Gastric Inhibitory Polypeptide; D052216:Glucagon-Like Peptide 1; D005947:Glucose