Flash monitoring is an option that comes with certain continuous glucose monitoring (CGM) systems, all of which involve wearing a sensor that is inserted into your skin and worn for several days continuously. While CGM systems record your glucose levels on a regular basis — typically every minute or so — taking a flash reading involves looking at the current reading from the sensor, which can be done by holding a scanning device such as a smartphone over the sensor in your arm. Software on the scanning device will show your latest glucose reading in about one second — allowing for a much faster glucose reading than traditional finger-stick test. This speed may help people check their glucose level more frequently throughout the day, and make adjustments to their food intake or insulin doses accordingly.
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For the latest study, flash glucose readings from 16,331 CGM systems were anonymously collected by researchers for analysis. This collection took place between September 2014 and March 2020. For each CGM system in the study — each presumably representing one person — the researchers calculated the rate of scanning for flash readings, and participants were placed in 20 groups of equal size based on how often they took flash readings (each group contained 817 participants).
More frequent flash readings linked to better blood glucose control
Overall, the median number of scans per day (the number at the very center of all participants) was 11.5. Participants in the top group for flash readings took an average of 40.0 scans per day, while those in the bottom group took an average of 3.7 scans. Those in the top group for scans had an average estimated A1C level (a measure of long-term blood glucose control) of 6.9%, while those who scanned the least had an average A1C level of 8.6%. Among all participants, taking more flash readings was linked to a greater proportion of time spent in the target glucose range of 70 mg/dl to 180 mg/dl. An estimated A1C level of 7.0% translated into spending about 65% of the time in the target range, 30% of the time with high glucose, and 5% of the time with low glucose — showing that even participants with the lowest A1C levels had room for improvement when it came to staying in the target glucose range.
The researchers concluded that among CGM system users, taking more frequent flash readings was linked to better overall glucose control. It’s important to note, though, that it’s not clear how big of a role more frequent readings actually played in glucose control. People who took more frequent readings may have been more vigilant about their glucose control in many different areas — including their diet, insulin dosing, physical activity, and more. But the sheer number of flash readings taken each day in the top group suggests that this type of glucose reading may play a helpful role in glucose control, since it’s unlikely that anyone would undertake 40 finger-stick glucose readings daily.
Want to learn more about blood glucose management? See our “Blood Sugar Chart,” then read “Blood Sugar Monitoring: When to Check and Why” and “Strike the Spike II: How to Manage High Blood Glucose After Meals.”
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