Comparison of breath gases, including acetone, with blood glucose and blood ketones in children and adolescents with type 1 diabetes.

Previous studies have suggested that breath gases may be related to simultaneous blood glucose and blood ketone levels in adults with type 2 and type 1 diabetes. The aims of this study were to investigate these relationships in children and young people with type 1 diabetes in order to assess the efficacy of a simple breath test as a non-invasive means of diabetes management. Gases were collected in breath bags and measurements were compared with capillary blood glucose and ketone levels taken at the same time on a single visit to a routine hospital clinic in 113 subjects (59 male, age 7 years 11 months-18 years 3 months) with type 1 diabetes. The patients were well-controlled with relatively low concentrations of the blood ketone measured (ß hydroxybutyrate, 0-0.4 mmol l(-1)). Breath acetone levels were found to increase with blood ß hydroxybutyrate levels and a significant relationship was found between the two (Spearman's rank correlation ρ = 0.364, p < 10(-4)). A weak positive relationship was found between blood glucose and breath acetone (ρ = 0.16, p = 0.1), but led to the conclusion that single breath measurements of acetone do not provide a good measure of blood glucose levels in this cohort. This result suggests a potential to develop breath gas analysis to provide an alternative to blood testing for ketone measurement, for example to assist with the management of type 1 diabetes.

Noise-immune cavity-enhanced optical heterodyne detection of HO2 in the near-infrared range.

Accurate measurements of the absolute concentrations of radical species present in the atmosphere are invaluable for better understanding atmospheric processes and their impact on Earth systems. One of the most interesting species is HO(2), the hydroperoxyl radical, whose atmospheric daytime levels are on the order of 10 ppt and whose observation therefore requires very sensitive detection techniques. In this work, we demonstrate the first steps toward the application of external-cavity diode-laser-based noise-immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS) to the detection of the HO(2) radical in the near-infrared range. Measurements of stable species and of HO(2) were made in a laboratory setting, and the possibilities of extending the sensitivity of the technique to atmospheric conditions are discussed.