Continuous glucose monitoring and recreational scuba diving in type 1 diabetes: head-to-head comparison between Free Style Libre 3 and Dexcom G7 performance.

Abstract

Background Scuba diving was previously excluded because of hypoglycemic risks for type 1 diabetic patients (T1DM). Specific eligibility criteria and a safety protocol have been defined, while continuous glucose monitoring (CGM) systems have enhanced diabetes management. This study aims to assess the feasibility and accuracy of CGM Dexcom G7 (DG7) and Free Style Libre 3 (FSL3) in a setting of repetitive scuba diving in T1DM, exploring the possibility of non-adjunctive use. Material and methods The study was conducted during an event of Diabete Sommerso® association in November 2023. Participants followed a safety protocol, with capillary glucose as reference standard (Beurer GL50Evo). Sensors accuracy was evaluated through Median and Mean Absolute Relative Difference (MeARD and MARD) and Surveillance Error Grid (SEG) Analysis. Sub-analyses were performed by glycemic range, timing, gender. Data distribution and correlation was estimated by Spearman test and Bland-Altman plots. The ability of sensors to identify hypoglycaemia was assessed by contingency tables. Participants completed a satisfation questionnaire. Results Data from 202 dives of 13 patients were collected. The overall MARD was 31% for DG7 and 14.2% for FSL3, MeARD 19.7% and 11.6% respectively. FSL3 exhibited better accuracy in normoglycemic and hyperglycemic ranges. SEG analysis showed 82.1% (DG7) and 97.4% (FSL3) data on no-risk zone. FSL3 better performed on hypoglycemia identification (diagnostic odds ratio of 254.10 vs 58.95). Neither of sensors reached the MARD for non-adjunctive use. Patient satisfaction favored FSL3 for size and minimal bulk, while DG7 received positive feedback for versatility. Conclusions The study reveals FSL3 superior accuracy compared to DG7 in a setting of repetitive scuba diving in T1DM, except for hypoglycemic range. Both sensors fails to achieve accuracy for non-adjunctive use. Capillary tests remain crucial for safe dive planning, and sensor data should be interpreted cautiously. We suggest exploring additional factors potentially influencing sensor performance.