The insulin tolerance test in morbidly obese patients undergoing bariatric surgery.
OBJECTIVE
To assess the effect of massive weight loss in relation to insulin resistance and its correlation to changes in glycemic homeostasis and lipid profile in severely obese patients.


METHODS
A prospective clinical intervention study was carried out with 31 morbidly obese women (body mass index: 54.2 +/- 8.8 kg/m(2)) divided into three groups according to their glucose tolerance test: 14 normal, 8 impaired glucose tolerance, and 9 type 2 diabetes. All subjects underwent an insulin tolerance test with intravenous bolus of 0.1 U insulin/kg body weight before silastic ring vertical gastroplasty Roux-en-Y gastric bypass surgery, and again at 2, 4, 6, and 12 months postoperatively. Fasting plasma glucose, hemoglobin A1c, and lipid profile were also evaluated.


RESULTS
A reduction of 68 +/- 15% in initial excess body weight was evident within 1 year. Along with weight loss, the following statistically significant changes were found: an increase in the insulin-sensitivity index (Kitt) and a decrease in fasting plasma glucose and hemoglobin A1c, most notably in the type 2 diabetes group. An overall improvement in lipid profile was observed in all three groups.


CONCLUSIONS
Bariatric surgery was an effective therapeutic approach for these obese patients because it reduced both weight and insulin resistance, along with improving metabolic parameters. Significant correlations were found between insulin resistance and metabolic improvements. Weight loss after bariatric surgery induced an improvement in metabolic fitness, related to the reduction in insulin resistance over a range of glucose tolerance statuses from normal to diabetic.
Geloneze
B
B
Endocrinology Service, Obesity Surgery Unit, Department of Surgery, University of Campinas, São Paulo, Brazil. Bgeloneze@aol.com
Tambascia
M A
MA
Pareja
J C
JC
Repetto
E M
EM
Magna
L A
LA
D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D002784:Cholesterol / Q000097:blood; D008076:Cholesterol, HDL / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000097:blood; D005215:Fasting; D005260:Female; D015390:Gastric Bypass; D018149:Glucose Intolerance / Q000097:blood; D005951:Glucose Tolerance Test; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D007328:Insulin; D007333:Insulin Resistance; D008875:Middle Aged; D009767:Obesity, Morbid / Q000097:blood* / Q000601:surgery*; D011446:Prospective Studies; D014280:Triglycerides / Q000097:blood; D015431:Weight Loss
D001786:Blood Glucose; D002784:Cholesterol; D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D006442:Glycated Hemoglobin; D007328:Insulin; D014280:Triglycerides