Washington: Obese children, facing a higher risk of pre-diabetes and Type-2 diabetes, might be undergoing a flawed screening test, according to a new study.

The standard screening test for high blood sugar in children with risk factors - called the blood glucose test - identified nearly three times fewer children with pre-diabetes than a longer blood test.

Katherine Morrison of McMaster University, Ontario, said the more accurate test was the glucose stress test, also called the oral glucose tolerance test.

This test takes longer because the patient has blood drawn after fasting and again two hours after drinking a sugary solution.

Compared with the glucose stress test, the fasting blood glucose test also was not as sensitive in detecting metabolic syndrome. This syndrome is a cluster of risk factors for heart disease and diabetes, including a high blood sugar level.

"Pre-diabetes and metabolic syndrome are common in obese children but are not readily identified with the currently recommended test," Morrison said. "They require a glucose stress test."

The authors studied 172 obese children, aged five to 17, who joined a programme to help attain a healthy weight. All children had evaluation of risk factors for diabetes or its precursor, pre-diabetes and metabolic syndrome, including testing of blood sugar.

Using the glucose stress test, the researchers found that 25 percent of the children met the diagnostic criteria for pre-diabetes. But when they relied on results of the fasting blood glucose test, as recommended by American and Canadian diabetes associations, they found that only eight percent of the children had pre-diabetes.

These results were presented Sunday at The Endocrine Society's 90th Annual Meeting in San Francisco.