RESUMO
Objective To conduct breath test with a relatively large number of subjects for new data regarding breath acetone in diabetes using a high accuracy and high data throughput breath acetone analyzer based on the cavity ringdown spectroscopy (CRDS) technique.Methods The CRDS breath analyzer was validated by standard acetone gas samples with various concentrations and golden standard gas chromatography-mass spectrometry (GC-MS).A total of 917 breath samples from 260 type 2 diabetic (T2D) patients and 30 healthy individuals were collected under each of 4 different conditions: fasting, 2 h post-breakfast, 2 h post-lunch, and 2 h post-dinner, and the samples were tested by the breath analyzer.Results The linear fitting curve of standard acetone samples with various concentration had good linearity (R=1, P＜0.05).The linear fitting of the results of GC-MS and CRDS was 0.98, suggesting that the obtained acetone concentrations using both methods were consistent.For the 260 T2D subjects, the exhaled breath acetone concentrations ranged from 0.0 to 10.6×10-6, while for the 30 healthy subjects, the breath acetone concentration ranged from 0.1 × 10-6 to 2.0× 10-6.The mean breath acetone concentration of the 260 T2D subjects was (1.5±1.l)× 10-6, which was 1.4 times of(1.1±0.5)×10-6 for the 30 healthy subjects.The mean breath acetone concentrations under the 4 conditions for the 260 T2D subjects ((1.6±1.2)×10-6, (1.4±1.0)×10-6~, (1.4±0.9)×10-6, and (1.4±1.2)× 10-6) were higher than that of the 30 healthy subjects ((1.3±0.3)×10-6, (1.0±0.6)×10-6, (1.0±0.6)×10-6, and (1.1±0.4)×10-6), respectively.No correlation was found between the breath acetone concentration and the blood glucose level of the T2D subjects and the healthy individuals.Conclusions The GC-MS validation confirms that the CRDS breath acetone analyzer is a reliable instrument for fast response and on-line breath acetone measurement.An elevated mean breath acetone concentration exists in T2D subjects.The relationship between breath acetone level and physiological parameters needs to be further investigated.