What you've heard
Everyone should wear a glucose monitor to find their spikes
Verdict
No evidence of benefit for people without diabetes
No evidence of benefit for people without diabetes. A curiosity, not a health tool, and no substitute for a blood test.
Should people without diabetes wear a glucose monitor?
No evidence of benefit for people without diabetes. A curiosity, not a health tool, and no substitute for a blood test.
The first over-the-counter continuous glucose monitor was cleared by US regulators in 2024 for adults not using insulin, with a warning that users "should not make medical decisions based on the device's output without talking to their healthcare provider." The devices show something real: blood sugar rises after meals, sometimes well above its fasting level. That is normal physiology. Even healthy, slim people spend about half an hour a day above the top of the usual range, and older people with normal blood sugar about three hours. The monitor's estimate of average blood sugar can run high in healthy people, and the trials of glucose-monitor feedback were almost all in people with diabetes, with modest effects and frequent industry ties.17
Where the book tests it
Sources
- 17.US Food and Drug Administration (2024). "FDA clears first over-the-counter continuous glucose monitor." Press announcement, 5 March 2024. https://www.fda.gov/news-events/press-announcements/fda-clears-first-over-counter-continuous-glucose-monitor; Shah, V.N., DuBose, S.N., Li, Z., Beck, R.W., et al. (2019). "Continuous glucose monitoring profiles in healthy nondiabetic participants: a multicenter prospective study." Journal of Clinical Endocrinology and Metabolism, 104(10), 4356-4364. https://doi.org/10.1210/jc.2018-02763; Spartano, N.L., Sultana, N., Lin, H., Cheng, H., et al. (2025). "Defining continuous glucose monitor time in range in a large, community-based cohort without diabetes." Journal of Clinical Endocrinology and Metabolism, 110(4), 1128-1134. https://doi.org/10.1210/clinem/dgae626 (time above 140 mg/dL; the community sample had a mean age of 58.5); Shah, V.N., Vigers, T., Pyle, L., Calhoun, P., and Bergenstal, R.M. (2023). "Discordance between glucose management indicator and glycated hemoglobin in people without diabetes." Diabetes Technology and Therapeutics, 25(5), 324-328. https://doi.org/10.1089/dia.2022.0544; Richardson, K.M., Jospe, M.R., Bohlen, L.C., Crawshaw, J., et al. (2024). "The efficacy of using continuous glucose monitoring as a behaviour change tool in populations with and without diabetes: a systematic review and meta-analysis of randomised controlled trials." International Journal of Behavioral Nutrition and Physical Activity, 21(1), 145. https://doi.org/10.1186/s12966-024-01692-6 (25 trials, none in healthy adults with normal blood sugar as a group; 11 had conflicts of interest tied to glucose monitors)
Note numbers are those of Chapter 5, Eat.
This verdict is one of the "What you've heard" boxes in Chapter 5, Eat, where the book tests the claims people repeat against the studies behind them.
Educational content, not medical advice. Disclaimer.