Breath Test Possible Diagnostic Screening Tool for Diabetes

Abnormal glucose tolerance can be detected by a carbon-13 labeled oral glucose tolerance test in which 13-CO2 excreted in the breath is measured with a standard breath analyzer, according to research conducted at the University of Texas Medical Branch in Galveston.

“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,” Dr. Melinda Sheffield-Moore of the University of Texas Medical Branch in Galveston and co-investigators report.
The research team collected blood and breath samples from 17 subjects at baseline and every 30 minutes for 10 hours after they consumed a drink containing 75 g glucose and 150 mg radiolabeled glucose. The investigators measured ratios of labeled-to-unlabeled CO2 in single breath samples using an infrared spectrophotometer.

Standard oral glucose tolerance test results indicated that 10 of the subjects had normal glucose tolerance (2-hour blood glucose < 140mg/dL. [7.8 mmol/L] ), and 7 had either pre-diabetes or early-stage diabetes (2-hour blood glucose 140mg.dL.[7.8-16 mmol/L]). Mean fasting plasma glucose levels in the two groups were 91.8mg/dL. and 122mg/dL. (5.1 and 6.8 mmol/L), respectively.

“Remarkably,” the authors write, “the breath analyzer was capable of detecting marked differences in glucose-derived breath CO2 kinetics between individuals (with normal and impaired glucose tolerance) within 60 minutes.”

The results showed that 13-CO2 abundance was significantly lower in the group with impaired glucose tolerance than in the nondiabetic subjects between 1 and 3 hours after the glucose load. Furthermore, the 2-hour 13-CO2 measurements significantly correlated with three measured indices of insulin resistance.

“The use of a point-of-care diagnostic breath 13-CO2 analyzer and storable breath collection bags is suitable for large-scale population testing in research as well as the clinical setting,” Dr. Sheffield-Moore and her associates note.
They anticipate future research to validate their findings and to establish diagnostic cutoff values.

Diabetes Care 2009;32:430-435.