Oral Glucose Tolerance Test Outcome Not Consistent in Overweight Pediatric Patients

In the November issue of The Journal of Clinical Endocrinology & Metabolism, Dr. Ingrid M. Libman of Children's Hospital of Pittsburgh and colleagues report that they came to this conclusion after studying 60 patients aged 8 to 17 years with a mean BMI in the 99th percentile.

The subjects underwent two oral glucose tolerance tests between 1 and 25 days apart. The results showed little concordance.

Of the 10 subjects with impaired glucose tolerance during the first test, only 3 had such findings during the second test. Agreement between the first and second test was only 22.2% for impaired fasting glucose and 27.3% for impaired glucose tolerance. Compared to results for 2-hour glucose, those for the fasting value had higher reproducibility.

Overall, subjects with discordant results were more insulin resistant and had a lower glucose disposition index "with higher risk of developing type 2 diabetes."
Co-author of an accompanying editorial, Dr. Philip S. Zeitler of the University of Colorado, Denver, stated that, "probably the most important points made in this article are that the oral glucose tolerance test in children is not adequately reproducible in the clinical setting, as has been previously demonstrated in adults."
"Therefore," he advised, "the results of a single test should not be relied upon to make the formal diagnosis of abnormalities in glucose metabolism. At the same time, however, the study suggests that even intermittent abnormalities in glucose metabolism may reflect early derangements in glucose regulation in at-risk kids."

J Clin Endocrinol Metab 2008;93:4231-4237.