Abstract
Many volatile organic compounds are present in exhaled breath and may represent by-products of endogenous biological processes. Ethanol is produced via alcoholic fermentation of glucose by gut bacteria and yeast, while acetone derives from oxidations of free fatty acids, influenced by glucose metabolism. We hypothesized that the integrated analysis of breath ethanol and acetone would provide a good approximation of the blood glucose profile during a glucose load. We collected simultaneous exhaled breath gas, ambient air, and serum glucose and insulin samples from 10 healthy volunteers at baseline and during an oral glucose tolerance test (OGTT) (ingestion of 75 g of glucose followed by 120 min of sampling). Gas samples were analyzed by gas chromatography/mass spectrometry. Mean glucose values displayed a typical OGTT pattern (rapid increase, peak values at 30-60 min, and gradual return to near baseline by 120 min). Breath ethanol displayed a similar pattern early in the test, with peak values at 30 min; this was followed by a fast return to basal levels by 60 min. Breath acetone decreased progressively below basal levels, with lowest readings obtained at 120 min. A multiple regression analysis of glucose, ethanol, and acetone was used to estimate glucose profiles that correlated with measured glucose values with an average individual correlation coefficient of 0.70, and not lower than 0.41 in any subject. The integrated analysis of multiple exhaled gases may serve as a marker of blood glucose levels. Further studies are needed to assess the usefulness of this method in different populations.
Highlights
THE HUMAN BREATH contains numerous volatile organic compounds (VOCs), many of them present at concentrations in the part per trillion range.[1]
We hypothesized that subtler changes in exhaled ethanol and acetone, significantly smaller than those observed in the conditions reported above, may occur during the comparatively small fluctuations in blood glucose that physiologically follow ingestion of a normal meal and that the integrated analysis of these exhaled gas profiles may yield an indirect assessment of circulating glucose levels
Peak serum glucose concentrations were recorded at 30 min (139 Ϯ 5 mg/dL, range 116–162 mg/dL), the highest reading in the whole data set was 185 mg/dL measured in one subject at 60 min
Summary
We collected simultaneous exhaled breath gas, ambient air, and serum glucose and insulin samples from 10 healthy volunteers at baseline and during an oral glucose tolerance test (OGTT) (ingestion of 75 g of glucose followed by 120 min of sampling).
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