The peer-reviewed research, published in The American Journal of Clinical Nutrition, warns that CGMs could be overestimating blood sugar levels in healthy adults, leading to unnecessary dietary changes
NEW DELHI — While continuous glucose monitors (CGMs) may be of significant help to people living with diabetes, they may harm healthy adults by showing inaccurate results that can lead to unnecessary food restrictions, according to a study on Wednesday.
CGMs were originally designed to help diabetics manage their blood sugar. It helps by tracking glycaemic index (GI) -- a measure of how quickly a food can make your blood sugar. However, these devices are now increasingly being used by health-conscious adults to track how different foods affect their glucose levels.
The peer-reviewed research, published in The American Journal of Clinical Nutrition, warns that CGMs could be overestimating blood sugar levels in healthy adults, leading to unnecessary dietary changes.
“CGMs are fantastic tools for people with diabetes because even if a measurement isn’t perfectly accurate, it's still better than not having a measurement at all. However, for someone with good glucose control they can be misleading based on their current performance,” said Professor Javier Gonzalez from the Department for Health, from the University of Bath.
“For healthy individuals, relying on CGMs could lead to unnecessary food restrictions or poor dietary choices. If you want to assess your blood sugar accurately, traditional methods are still the way to go. We want to better identify the sources of the error in CGMs so that we can improve their performance in the future and have active research on this topic,” Gonzalez added.
Researchers measured blood sugar responses in healthy volunteers (non-diabetic, within a healthy BMI range) using two methods -- a CGM and the gold standard finger-prick test -- to assess the accuracy of CGMs in fruit-based products, ranging from whole fruit to smoothies.
The CGM consistently reported higher blood sugar levels compared to finger-prick tests. When participants consumed a smoothie, the device overestimated the GI by 30 per cent, reporting a GI of 69 (medium) compared to the traditional test result of 53 (low).
Whole fruit was misclassified as medium or high-GI foods by CGMs, while the finger-prick test showed they were low-GI. This could lead users to mistakenly believe that fruit could cause harmful spikes in blood sugar.
The research also debunked the common myth that blending fruits into a smoothie raises their GI. Whether eaten whole or blended, fruits like apples, bananas, mangoes, and oranges remained low on the GI.
CGMs are unlikely to be a valid method to determine whether a food has high or low GI, said the researchers.
Gonzalez said the CGMs may be inaccurate because they measure glucose in the fluid surrounding your cells, not directly in your blood. “This can lead to discrepancies due to factors like time delays, blood flow, and how glucose moves between different parts of the body.”