Is a glucose meter useful if you don't have diabetes?

A glucose meter, and especially a continuous glucose monitor (CGM) that measures around the clock via a sensor on the skin, also gives people without diabetes insight into how their blood sugar responds to meals, exercise and stress. A study of 153 healthy individuals (aged 7 to 80) found that blood sugar in healthy people falls between 70 and 140 mg/dL 96% of the time, with an average of approximately 98-99 mg/dL. People over 60 had a slightly higher average of 104 mg/dL. These reference figures are useful, but they do not prove that monitoring automatically leads to better health.

CGM could be of value for healthy adults in the early detection of impaired blood sugar regulation, for adjusting dietary and exercise behaviour, and for making the body's stress responses visible. In a large cohort of more than 7,000 non-diabetics (aged 40 to 70), higher average glucose levels were associated with abnormalities on retinal photographs and poorer sleep patterns. These are interesting associations, but they remain just that: associations. We do not know whether those higher glucose levels are the cause of these abnormalities, or whether a shared underlying factor is involved.

Among endurance athletes, the use of CGM to fine-tune nutrition around training is growing. However, there is as yet no scientific consensus on how to interpret CGM data in athletes, and clear protocols are lacking. One notable finding: after a week of extremely high training load, healthy subjects showed a marked deterioration in glucose tolerance and mitochondrial function, and elite athletes demonstrated measurably poorer glucose regulation via CGM than a comparable control group. This shows that in athletes CGM can also reveal unexpected, concerning patterns that would otherwise go unnoticed.

Scientists are also combining CGM data with artificial intelligence. In a large study of approximately 28,000 participants (the Human Phenotype Project), an AI model trained on CGM and nutritional data outperformed existing methods in predicting disease onset. This is promising, but the research is still in its infancy and cannot be directly translated to individual use of a sensor.

The common thread running through all available studies is that the clinical benefit of CGM for healthy people has not yet been demonstrated in long-term, controlled research. We know that the measurements yield interesting information, but we do not yet have a good understanding of how to best interpret that data in non-diabetics, whether monitoring leads to better decisions, or whether those better decisions ultimately produce health gains. The sensor can also cause anxiety or unnecessary concern about normally varying blood sugar levels, although that risk is not explicitly mentioned in the available claims.