78-OR: Breath Acetone Correlates with Capillary Beta Hydroxybutyrate in Type 1 Diabetes

Introduction: Prior work has shown a linear relationship between breath acetone (BrACE) and capillary blood beta hydroxybutyrate (BOHB) in persons without diabetes. This innovative study investigates the correlation between capillary BOHB and BrACE in T1D during usual care and while taking an SGLT2 inhibitor in both insulin-sufficient and -deficient states. The primary outcome of the study is the correlation of capillary BOHB and BrACE.

Methods: Participants provided written consent and were randomized to 2 weeks of usual care and 1 day of insulin withdrawal followed by 2 weeks of usual care plus dapagliflozin, 10 mg daily and 1 day of insulin withdrawal or the opposite sequence. Paired BOHB (Precision Xtra®, Abbott) and BrACE (Biosense®, Readout) were obtained 3X daily for 2 weeks, then hourly during supervised insulin withdrawal. Sick day rules were reviewed and insulin doses were minimally adjusted when taking dapagliflozin. The data was tested for normality and the Spearman’s test was utilized due to non-normally distributed data.

Results: Participant age was 48 ±18 years (mean ± SD), baseline A1c 7.0 ± 0.9%, and CGM time in range [70-180mg/dL] 61 ± 18%. During outpatient care, BrACE and BOHB were weakly correlated both without dapagliflozin (n=689 paired readings; Spearman’s ρ = 0.44; 95% CI: 0.37 to 0.50) and with dapagliflozin (n=718 paired readings; ρ = 0.32; 95% CI: 0.25 to 0.39). However, BrACE and BOHB were strongly correlated during supervised insulin withdrawal (n=246 paired values, ρ = 0.81; 95% CI: 0.77 to 0.85). In ROC analysis, BrACE of ≥ 5 demonstrated optimal sensitivity (93%) and specificity (87%) for detecting a capillary BOHB <u>></u> 1.5 mmol/L. No serious adverse events occurred.

Conclusion: In adults with T1D, BrACE monitoring provides a noninvasive estimate of ambient ketone levels when compared to blood BOHB but is more useful under supervised conditions with greater range of ketone production and less potential for interference with volatile organic compounds than in typical outpatient settings.