To Örebro University

BACKGROUND: This study evaluated the accuracy and function of the Continuous Glucose Monitoring System (CGMS, Minneapolis, MN) during recreational scuba diving in individuals with type 1 diabetes.

METHODS: Twenty-four adults, 12 with type 1 diabetes and 12 healthy controls, were studied during five recreational scuba dives performed on three consecutive days. All the participants used the CGMS on all the days and during all the dives. Comparisons were made between plasma glucose at specific time intervals and the CGMS.

RESULTS: The recording by the CGMS was robust, with few sensor problems. The mean sensor survival time was >48 h. Eighty-five percent of the individuals used one sensor during the entire length of the trial. The overall mean absolute difference (MAD) within the group with diabetes was 14.4 +/- 6%, and the corresponding daily figures were 23.2 +/- 19.3% on day 1, 11.6 +/- 4.5% on day 2, and 11.2 +/- 5.7% on day 3. A significant improvement regarding MAD when day 1 was compared with day 2 and 3 (P < 0.05). With a limit set at 70 mg/dL, hypoglycemia pre- and post-dive was detected with a positive predictive value of 0.39, negative predictive value of 0.98, sensitivity of 0.64, and specificity of 0.94.

CONCLUSIONS: We demonstrate that the CGMS was used with accuracy in such difficult conditions as scuba diving and provided robust information on glucose variations.