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Breath analysis offers potential for noninvasive blood sugar monitoring in diabetes

September 25, 2007

Diabetics found to have elevated methyl nitrate content in exhaled breath

Irvine, Calif. - Breath-analysis testing may prove to be an effective, non-invasive method for monitoring blood sugar levels in diabetes, according to a University of California, Irvine study.

By using a chemical analysis method developed for air-pollution testing, UC Irvine chemists and pediatricians have found that children with type-1 diabetes exhale significantly higher concentrations of methyl nitrates when they are hyperglycemic.

The study heralds the potential of a breath device that can warn diabetics of high blood sugar levels and of the need for insulin. Currently, diabetics monitor blood sugar levels using devices that break the skin to attain a small blood sample. Hyperglycemia is common in type-1 diabetes mellitus.

Study results appear this week in the early online version of the Proceedings of the National Academy of Sciences.

"Breath analysis has been showing promise as a diagnostic tool in a number of clinical areas, such as with ulcers and cystic fibrosis," said Dr. Pietro Galassetti, a diabetes researcher with the General Clinical Research Center (GCRC) at UC Irvine. "While no clinical breath test yet exists for diabetes, this study shows the possibility of non-invasive methods that can help the millions who have this chronic disease."

In the study, Galassetti, Dr. Dan Cooper and Andria Pontello of the GCRC conducted breath-analysis testing on 10 children with type-1 diabetes mellitus. The researchers took air samples during a hyperglycemic state and progressively as they increased the children's blood insulin levels.

The breath samples were sent to the laboratory of UC Irvine chemists F. Sherwood Rowland and Donald Blake, who examined the exhaled breath using methods developed for their atmospheric chemistry work. In that work, they measure the levels of trace gases in excess of the parts-per-billion range that contribute to local and regional air pollution. Their research group is one of the few in the world recognized for its ability to measure accurately at such small amounts.

The Rowland-Blake group analyzed the children's breath samples for more than 100 gasses at parts-per-trillion levels and found methyl nitrate exhaled concentrations to be increased as much as 10 times more in diabetic children during hyperglycemia than when they had normal glucose levels. The methyl nitrate concentrations corresponded with the children's glucose levels - the higher the glucose, the higher the exhaled methyl nitrates.

Galassetti said that during hyperglycemia, in type 1 diabetes there are more fatty acids in the blood that cause oxidative stress. Methyl nitrate is likely a by-product of this increased oxidative stress. It is commonly present in ambient air at very low concentrations, Galassetti noted, and normally appears in the exhaled breath samples of healthy subjects at parts-per-trillion levels.

"Currently, we are involved with new studies looking at the correlation of other gases with hyperglycemia and other variables, including insulin," Galassetti said. "Eventually, we hope to put together a full exhaled gas profile of diabetes, and our efforts look promising."

University of California - Irvine