Grapevine, Tex. — A patient's preoperative estimated glucose disposition index provides a potent predictor of the likelihood of type 2 diabetes remission after gastric bypass for severe obesity, results of a 270-patient series suggest.
“This is a nice practical application of a parameter you can determine very simply in your clinic … You can tell somebody whether they have a very good chance or less good chance of cure,” Dr. Richard A. Perugini said at the annual meeting of the American Society for Metabolic and Bariatric Surgery.
Dr. Perugini of the University of Massachusetts, Worcester, reported on a consecutive series of 270 morbidly obese patients scheduled for laparoscopic gastric bypass for whom he determined the homeostatic model of assessment (HOMA)–estimated glucose disposition index. Seventy of these patients had type 2 diabetes.
The glucose disposition index (GDI) is the product of insulin sensitivity multiplied by beta cell sensitivity. It provides an indication of how advanced a patient's type 2 diabetes is. Both insulin sensitivity and beta cell sensitivity can readily be estimated by plugging data from an oral glucose tolerance test into the HOMA calculator developed by and available for free download from the Diabetes Trials Unit at the University of Oxford, England (www.dtu.ox.ac.uk
Dr. Perugini found that 1 year post surgery, the patients in the top one-third of GDI values preoperatively had a 94% rate of diabetes remission (symptom free and off all diabetes medications). This was significantly greater than the 78% diabetes remission rate in patients in the middle tertile for GDI or the 71% rate for the lowest tertile.
In a multivariate logistic regression analysis incorporating patient age, gender, preoperative body mass index, and other variables, a presurgical HOMA-estimated that a GDI greater than 29 was an independent predictor of postsurgical diabetes remission, conferring a 7.9-fold increased likelihood of remission.
The only other significant predictive factor was preoperative use of insulin; insulin users had a 1 in 8 chance of diabetes remission after surgery.
Dr. Perugini noted that the traditional gold standard for studying insulin sensitivity and beta cell sensitivity is the insulin and glucose clamp. In his view, it's a test with major drawbacks.
“It's quite a cumbersome test, it's expensive, and it's not at all physiologic,” the surgeon said. “Regardless of what your thoughts on the HOMA are, it actually works.”