COMMENTS AND RESPONSES Novel Noninvasive Breath Test Method for Screening Individuals at Risk for Diabetes

W e thank Dr. Davidson (1) for hisinsightful alternative to the inter-pretation of our results (2). While the validity of the breath test method to distinguish between individu-als with normal glucose tolerance (NGT) and pre-diabetes and early-stage diabetes (PDED) is not affected by this interpreta-tion, he brings up a valid point that tracer dilution due to differences in fasting glu-cose may influence the appearance of 13CO2 in breath. However, we argue that the shapes of the curves we obtained for NGT and PDED do not support this as the only explanation. We expect that a dilu-tion effect by itself would have mainly af-fected themagnitude of the 13CO2 peak