A breath test can spot someone whose metabolism is not handling glucose properly, indicating that he or she runs the risk of becoming diabetic, scientists report.

For the test, the subject drinks a solution of glucose labeled with a short-lived radioisotope, carbon-13. A breath analyzer then measures the amount of exhaled carbon dioxide labeled with carbon-13.

"This novel breath test method may assist in recognition of pre-diabetes or early-stage diabetes in at-risk persons without the need for invasive blood sampling, thus making it an attractive option for large-scale testing of at-risk populations, such as children," the researchers write in the medical journal Diabetes Care.

To test the method, Dr. Melinda Sheffield-Moore, at the University of Texas Medical Branch in Galveston, and her colleagues collected blood and breath samples from 17 subjects every 30 minutes for 10 hours after they consumed a drink containing radiolabeled glucose. The team measured glucose level in the blood samples and the ratio of labeled-to-unlabeled carbon dioxide in the breath samples.

Based on the blood glucose readings, 10 of the subjects were normal while 7 had either pre-diabetes or early-stage diabetes.

"Remarkably," the investigators report, "the breath analyzer was capable of detecting marked differences in glucose-derived breath carbon dioxide kinetics between (normal and pre-diabetic) individuals within 60 minutes."

Specifically, the amount of carbon-13 labeled carbon dioxide was much lower in the pre-diabetic group than the non-diabetic subjects between 1 and 3 hours after the glucose load.

Sheffield-Moore and her associates suggest that it would be feasible to use a breath analyzer and storable breath collection bags for large-scale diabetes screening.