BACKGROUND: Breath acetone (BrACE) is an end product of ketone metabolism that is measurable by noninvasive breath ketone analyzers. We assessed the correlation between capillary blood β-hydroxybutyrate (BOHB) and BrACE in people with type 1 diabetes (T1D) during 14 days of outpatient care with and without dapagliflozin treatment and during supervised insulin withdrawal studies with and without dapagliflozin. METHODS: In this randomized crossover study, participants completed 14-day two outpatient periods with or without dapagliflozin 10 mg daily. Each 14-day unsupervised outpatient period was followed by a one-day supervised insulin withdrawal study. Paired BOHB and BrACE measurements were obtained three times daily during outpatient periods, then hourly during supervised insulin withdrawal. The correlation between BrACE and BOHB was assessed by Spearman's ρ. RESULTS: Twenty people with T1D completed the study. During outpatient periods, BrACE and BOHB were moderately correlated (n=1425 paired readings
ρ = 0.41
95% CI: 0.36 to 0.45
CONCLUSIONS: In adults with T1D, measurement of breath acetone provides a noninvasive estimate of blood BOHB concentration. The correlation between BrACE and BOHB was suboptimal during unsupervised outpatient care, but was strong during supervised insulin withdrawal.Trial registration: clinicaltrials.gov (NCT05541484).