The Impact of Identifying Sleep with a Fitbit on Calculated Rates of Nocturnal Hypoglycemia-The Hypo-Metrics Study

Consensus defines nocturnal hypoglycemia as occurring between 00:00 and 06:00 hrs. However, this may introduce bias, as for many, these hours only partially match real sleeping hours. Therefore, we compared rates of hypoglycemia while asleep (defined by Fitbit Charge 4) to rates of conventionally-defined nocturnal hypoglycemia. Hypo-METRICS study participants wore a Fitbit charge 4 and blinded FreeStyle Libre glucose monitor for up to 70 days. Every hypoglycemia episode (≤70mg/dL or ≤54mg/dL for ≥15 min) was classified as ‘asleep’ or ‘awake’ based on Fitbit sleep intervals and ‘nocturnal’ (00:00-06:00 hrs) or ‘day-time’. We compared weekly sensor-detected hypoglycemia (SDH) rates whilst asleep to nocturnal SDH rates using a paired sample Wilcoxon test. We included 542 participants (269 with type 1 diabetes, median (IQR) age 56 (44-66) years, HbA1c 7.3%(6.7-7.9), with 69 (65-70) nights with sleep data/participant). Sleep duration was 6.1 (5.2-6.8) hours. Median weekly rates of SDH while asleep were higher than rates of nocturnal SDH both ≤70mg/dL (1.3 (0.6-2.5) vs 0.9 (0.4-1.8), p<0.001) and ≤54mg/dL (0.4 (0.2-0.9) vs 0.3 (0.1-0.7), p<0.001). Stratifying by type of diabetes did not change the direction or magnitude of the differences in SDH rates. Using clock time to estimate nocturnal hypoglycemia underestimates hypoglycemia whilst asleep by up to a third. Using activity trackers such as Fitbit to identify sleep offers a novel way to estimate hypoglycemia whilst asleep to better reflect lived experience of nocturnal hypoglycemia. Disclosure G.Martine-edith: Other Relationship; Novo Nordisk A/S. R.J.Mccrimmon: Advisory Panel; Sanofi, Speaker's Bureau; Novo Nordisk A/S. E.Renard: Consultant; Abbott Diabetes, Dexcom, Inc., AstraZeneca, Boehringer-Ingelheim, Eli Lilly and Company, Insulet Corporation, MannKind Corporation, Novo Nordisk, Sanofi, Roche Diabetes Care. S.R.Heller: Advisory Panel; Zealand Pharma A/S, Zucara Therapeutics, Other Relationship; Eli Lilly and Company, Research Support; Dexcom, Inc., Speaker's Bureau; Novo Nordisk, Medtronic. M.Evans: Advisory Panel; Zucara Therapeutics, Pila Pharma, Dexcom, Inc., Other Relationship; Novo Nordisk, AstraZeneca, Abbott Diabetes, Speaker's Bureau; Eli Lilly and Company. J.K.Mader: Advisory Panel; Novo Nordisk A/S, Abbott Diabetes, Roche Diabetes Care, Eli Lilly and Company, Sanofi, Medtronic, Becton, Dickinson and Company, Pharmasense, embecta, Research Support; A. Menarini Diagnostics, Abbott Diabetes, Roche Diabetes Care, Dexcom, Inc., Profusa, Inc., Speaker's Bureau; Novo Nordisk A/S, A. Menarini Diagnostics, Abbott Diabetes, Roche Diabetes Care, Eli Lilly and Company, Sanofi, Boehringer Ingelheim Inc., Becton, Dickinson and Company, Ypsomed AG, Viatris Inc., Servier Laboratories, Medtrust, Stock/Shareholder; Decide Clinical Software GmbH. S.A.Amiel: Advisory Panel; Medtronic, Other Relationship; Sanofi, Novo Nordisk. P.Choudhary: Advisory Panel; Medtronic, Novo Nordisk, Dexcom, Inc., MannKind Corporation, Insulet Corporation, Research Support; Abbott Diabetes, Speaker's Bureau; Sanofi, Lilly. Hypo-resolve consortium: n/a. P.Divilly: None. N.Zaremba: None. U.Soeholm: Employee; Novo Nordisk A/S. A.Kingsnorth: None. Z.Mahmoudi: Employee; Novo Nordisk. M.Gomes: Employee; Novo Nordisk A/S. B.E.De galan: Research Support; Novo Nordisk. U.Pedersen-bjergaard: Advisory Panel; Novo Nordisk A/S, Sanofi, Vertex Pharmaceuticals Incorporated. Funding Innovative Medicines Initiative 2 Joint Undertaking (777460)