Study published in The American Journal of Clinical Nutrition warns that CGMs may provide inaccurate readings for healthy adults, leading them to make unnecessary changes to their diets
Continuous glucose monitors (CGMs), originally designed to help people with diabetes manage blood sugar levels, may be misleading for healthy adults, according to a study published on Wednesday. The research highlights how the devices can overestimate blood sugar levels, potentially leading to unnecessary dietary restrictions.
CGMs track blood sugar fluctuations by measuring the glycaemic index (GI) of foods, which indicates how quickly a food raises blood sugar. While these monitors are vital for diabetics, they have recently gained popularity among health-conscious individuals eager to assess how different foods impact their glucose levels.
However, the study published in The American Journal of Clinical Nutrition warns that CGMs may provide inaccurate readings for healthy adults, leading them to make unnecessary changes to their diets.
Professor Javier Gonzalez from the Department for Health at the University of Bath explained, “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 healthy individuals, relying on CGMs could lead to unnecessary food restrictions or poor dietary choices.”
Gonzalez further emphasized that traditional blood sugar monitoring methods, such as the finger-prick test, remain more accurate for healthy individuals. He also noted the need for further research to identify the causes of inaccuracies in CGMs to improve their performance.
In the study, researchers compared the accuracy of CGMs with the traditional finger-prick test for blood sugar measurement. The study involved healthy volunteers (non-diabetic, within a healthy BMI range) who consumed various fruit-based products, including whole fruits and smoothies.
The results revealed that CGMs consistently overestimated blood sugar levels. For instance, when participants consumed a smoothie, the CGM reported a glycaemic index (GI) of 69, classifying it as medium GI. In contrast, the traditional test showed a GI of 53, categorizing the smoothie as low GI. The CGM also misclassified whole fruits as medium or high GI, while the finger-prick test classified them as low GI foods.
These inaccuracies could lead users to mistakenly believe that fruits, which are generally low-GI, could cause harmful blood sugar spikes. The study also debunked the myth that blending fruits into a smoothie increases their glycaemic index. Fruits like apples, bananas, mangoes, and oranges retained their low GI whether eaten whole or blended.
The researchers concluded that CGMs are not a reliable method for determining the glycaemic index of foods. Gonzalez explained that the inaccuracies arise because CGMs measure glucose in the fluid surrounding cells, rather than directly in the blood. Factors such as time delays, blood flow, and how glucose moves throughout the body can contribute to discrepancies between CGM readings and the traditional finger-prick test.
In conclusion, while CGMs remain invaluable for people with diabetes, the study emphasizes the need for caution when healthy adults use these devices for glucose tracking. For accurate blood sugar measurements, traditional methods are still the most reliable approach.
