1949-P: Perioperative Accuracy and Reliability of CGM in Cardiac Surgery

Introduction and Objective: CGM accuracy during cardiac surgery and early postop recovery is not well defined. We evaluated the accuracy and reliability of a current-generation CGM across the perioperative period. Methods: 15 adults with T2D (HbA1c 6.9±0.9%) undergoing open cardiac surgery wore three Dexcom G7 CGMs (upper arm, forearm, abdomen) from 1 day preop through 48 h postop. CGMs not within ±20/20 of preop POCT were calibrated. Routine ABG and POCT collections served as intra and postop reference glucose values, respectively. Results: Of 45 sensors, 4 failed preop (1 replaced), none failed intraop or postop, and 18 required preop calibration. Mean intraop time was 4.6±1.4 h; prolonged signal loss (≥15 min) occurred on 5 occasions in 3 sensors (3.1% of intraop time), without clustering by surgical phase (e.g., bypass) or impacting postop data availability. Accuracy metrics are summarized in the Table. Sensor-level MARDs showed moderate variability (median intraop 8.7% [IQR 6.1-11.9%]; postop 12.2% [IQR 8.6-14.7%]) without consistent intraop-postop relationship. Conclusion: CGM use was feasible in cardiac surgery with minimal prolonged signal loss, limited to forearm use. Intraop accuracy was acceptable across sites. Postop accuracy was lower which may reflect the glucose reference changing from ABG intraop to POC postop rather than intrinsic sensor reliability. These findings support potential CGM integration in surgical care but larger studies must optimize site selection and protocols. Disclosure E. Zakheim: None. M.B. Pasmooij: None. R. Deshmane: None. M. Basina: None. J. Boyd: Other - DSMB; Current; Medtronic. D.R. Drover: Stock/Shareholder; Current; Vine Medical, World Medical COnceirge. A. Peterson: Research Support; Current; Octapharma. R. Lal: Consultant; Current; Abbott Diabetes, Adaptyx Biosciences. Consultant; Ended; Biolinq, Capillary Biomedical, Deep Valley Labs. Consultant; Current; Gluroo, Portal Diabetes, Tidepool. Advisory Panel; Ended; ProventionBio, Lilly, Sanofi, Rezolute. V. Fielding-Singh: Research Support; Current; Seastar Medical, Calcimedica, PyrAmes. Research Support; Ended; Dexcom, Inc. M.S. Hughes: Consultant; Current; Dexcom, Inc., Sanofi, Sequel Med Tech, LLC. Funding CGM devices were provided by Dexcom, Inc. through an investigator-initiated research agreement. Dexcom had no role in study design or data analysis.