Continuous glucose monitor overestimates glycemia

Researchers warn continuous glucose monitors can overestimate blood sugar levels

https://www.sciencedirect.com/science/article/pii/S0002916525000929?via%3Dihub

The research measured blood sugar responses in healthy volunteers (non-diabetic, within a healthy BMI range) using two methods: a CGM (the Abbot Freestyle Libre 2, a commercially available device, also provided on the NHS) and the gold standard finger-prick test. The research aimed to assess the accuracy of CGMs in measuring responses to various fruit-based products, ranging from whole fruit to smoothies. The findings were striking. The CGM consistently reported higher blood sugar levels compared to finger-prick tests. When participants consumed a smoothie, the Abbott Freestyle Libre 2 CGM overestimated the GI by 30%, 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. CGMs overestimated the time spent above the blood sugar level threshold recommended by Diabetes UK, by nearly 400%, potentially causing unnecessary worry for people whose blood sugar is actually well-controlled. 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 glycaemic index. The research concludes that CGMs are unlikely to be a valid method to determine whether a food is high or low-GI.