Safety of recreational scuba diving in type 1 diabetic patients: the Deep Monitoring programme

Aim: To verify whether, with thorough practical and theoretical training, well-controlled, non-complicated diabetic patients can safely go diving underwater with no additional medical or metabolic risks. Methods: Twelve diabetic patients participated in the study after undergoing training focused on their diabetic status. Two dives per day were scheduled during two five-day stays on the island of Ventotene (Italy). Capillary blood glucose (BG) was checked at 60, 30 and 10 minutes before diving, and corrective measures adopted if necessary, based on BG absolute levels and dynamics. A device for continuous subcutaneous glucose monitoring (CGM), expressly modified for the purpose, was worn during dives. Results: Data were gathered from 90 dives; mean BG at 60, 30 and 10 minutes before diving was 205.8 ± 69.6 mg/dL, 200.0 ± 66.4 mg/dL and 200.5 ± 61.0 mg/dL, respectively. In 56 of the 90 dives, supplementary carbohydrates or insulin were necessary, but only one dive was interrupted on account of hypoglycaemic symptoms. Mean post-dive BG was 158.9 ± 80.8 mg/dL. CGM recordings showed that glucose levels gradually decreased during the dives (nadir: -19.9%). Conclusion: Experienced, well-controlled, complication-free young diabetic patients can safely go scuba diving, provided that they apply a rigorous protocol based on serial pre-dive BG measurements. The specific variables of underwater diving do not appear to involve significant additional risks of hypoglycaemia.