531-P: Continuous Glucose Monitoring Placement during Physical Activity

Objectives: Individuals living with type 1 diabetes (T1D) are encouraged to participate in physical activity (PA) . It is vital that technology used to manage diabetes, such as a continuous glucose monitor (CGM) , provides reliable results during and after exercise. Currently, the Dexcom G6 CGM is approved to be inserted on the abdomen or upper buttock. The following study compared various location sites to assess reliability of those differing locations during times of moderate intensity PA. Methods: Thirty adolescents and young adults (age 13-20 years, µ=14.3 years) with T1D performed moderate intensity PA on a treadmill. Intensity was determined by Karvonen heart rate reserve formula. The PA consisted of walking/jogging for 40 minutes, with a 10-minute break occurring at the halfway point. Dexcom G6 CGM and glucometer measurements were collected and analyzed every minutes during and after exercise. Dexcom locations included arm, abdomen, thigh, and upper buttock. Analysis of accuracy metrics included mean absolute relative difference (MARD) and clinical reliability was assessed by Clarke Error Grid Analysis. Results: Analysis of CGM location sites revealed that CGMs placed on the arm and buttocks, statistically, had a worse MARD in comparison to abdomen. The CGM being placed on the buttocks increased the MARD by a ratio of 2.15 when compared to the abdomen. Additionally, we found that individuals who wore the CGM on their buttocks had an increased risk of having glucoses in Zone D of the Clarke Error Grid in comparison to those wearing it on the abdomen. Conclusions: The results suggest that CGM location does matter during and after exercise, with the abdomen providing the most reliable results. Furthermore, we found that CGM placement on the buttocks may lead to failure to detect dysglycemia during exercise. We hypothesize this may be due to interstitial fluid changes in actively exercising muscles which alter the accuracy during exercise. However, additional research in this area is needed to support this theory.