Exhaled breath isoprene rises during hypoglycemia in Type 1 Diabetes

Hypoglycemia and/or fear of hypoglycemia are major challenges for many with type 1 diabetes (T1D), limiting ability to lower glycemia. Given anecdotal reports of domestic pets alerting owners to blood glucose changes, especially hypoglycemia (1), we hypothesized that volatile organic compounds (VOCs) in exhaled breath might change at low glucose. We studied eight female nonsmoking participants with T1D (aged 46 ± 5 years, diabetes duration 23 ± 7 years, none treated with statins) twice using a single-blinded, computer code–randomized crossover design. An independent research ethics committee approved studies in advance, and subjects provided written consent. Using a stepped insulin clamp (Actrapid; Novo Nordisk, Crawley, U.K.; 0.3 mU/kg/min increasing to 1.5 mU/kg/min), on one occasion (STEP), arterialized plasma glucose (Yellow Springs Instrument 2300 STAT Plus Analyzer) was raised sequentially (7.1 ± 0.8, 8.7 ± 0.4, and 10.7 ± 0.1 mmol/L) then lowered with higher insulin infusion to 4.3 ± 0.3 and 2.8 ± …