Zaharieva DP, Riddell MC, Henske J. The accuracy of continuous glucose monitoring and flash glucose monitoring during aerobic exercise in Type 1 diabetes. J Diabetes Sci Technol. 2018 Oct 7:1932296818804550. doi: 10.1177/1932296818804550. [Epub ahead of print]
Significance of the research:
For patients living with type 1 diabetes, the traditional method for self-monitoring of blood glucose (SMBG) is using a fingerstick capillary blood sample and a glucose meter. With recent advancements in technology, devices have emerged that measure glucose levels using a sensor that is implanted under the skin and can detect interstitial glucose changes over 24 hours. These glucose values can then be wirelessly displayed on a number of different devices including an insulin pump, a smartphone, or a handheld receiver. Overall, these devices provide valuable information to patients with type 1 diabetes such as trend arrows indicating the direction glucose values are going and alerts when glucose levels go too high or too low. However, research has shown that there are often delays between interstitial and blood glucose levels during exercise and this may result in an underestimation of the true change in blood glucose during exercise.
In this case study, we present data on one physically active male with type 1 diabetes that completed 13 continuous, steady state moderate-intensity or ‘aerobic’ exercise sessions to compare the accuracy of three different glucose-monitoring devices to SMBG. We found that glucose-monitoring devices correlate well with SMBG during periods of relatively stable blood glucose levels; however, a 10-15 minute delay was observed during exercise when blood glucose levels dropped rapidly. In summary, all glucose-monitoring devices tended to overestimate glucose values with moderate-intensity exercise. Due to the observed delay in interstitial glucose as compared to SMBG during exercise, we recommend to initiate carbohydrate feeding sooner when the patient is relying on glucose-monitoring devices for decision-making.