Continuous glucose monitoring
What is continuous glucose monitoring?
A continuous glucose monitor is a small sensor worn on the arm or belly that reads glucose in the fluid under the skin every few minutes and sends it to a phone. It is a standard tool for diabetes. Since 2024, over-the-counter sensors let people without diabetes see how food, exercise and sleep move their glucose.
Listed here because well-known people have tried it on themselves. Trying something is not recommending it; each entry says whether the person tells others to do it.
Who has tried it
Tried by 4 people we can source: 3 kept, 1 stopped.
Kept
Peter AttiaPhysician, author of OutliveOutlive and Medicine 3.0 (Peter Attia)
Started 2015 · Does not recommend it to others
Has worn a glucose monitor for years to see how food, exercise and poor sleep move his glucose, and calls it a useful tool rather than a necessity.
“I remember for me, it’s been about eight years since I started.”
The Tim Ferriss Show, Dr. Peter Attia on Outlive (transcript, March 2023) · Status checked March 17, 2023 · Suggest a correction
Casey MeansPhysician, co-founder of Levels
Started 2019 · Recommends it to others
Had worn a sensor continuously for about a year and a half by mid-2021 and used it to find foods such as sweet potato that spike her glucose; she co-founded Levels, a CGM company, and promotes CGMs for people without diabetes.
“Almost a year and a half. I can't even imagine taking it off.”
The Melanie Avalon Biohacking Podcast #96, Casey Means on continuous glucose monitors (transcript, June 2021) · Status checked June 3, 2021 · Suggest a correction
Michael SnyderGeneticist at Stanford
Dates not stated · Recommends it to others
Wears a continuous glucose monitor along with several smartwatches and an Oura ring as part of tracking his own health, after his lab's profiling caught the onset of his type 2 diabetes.
“I had a pulled pork sandwich and I ate this and I watched my glucose just go up, to start going over 300.” Source of quote
Stanford Magazine, Body Count: how Michael Snyder's self-monitoring project could transform human health (December 2021) · Status checked December 1, 2021 · Suggest a correction
Stopped
Eric TopolCardiologist at Scripps Research, author of Super Agers
Dates not stated · Does not recommend it to others
Wore a glucose sensor for a two-week Weizmann Institute diet study; the diet it produced favored foods he disliked and high-oxalate foods he must avoid after kidney stones.
“I had several glucose spikes as high as 160 milligrams per deciliter of blood”
The New York Times, The A.I. Diet, by Eric Topol (March 2019) · Status checked March 2, 2019 · Suggest a correction
What the evidence shows
Monitors show things a single fasting test misses. In one Stanford study, people classed as normal by standard tests still spent some time in prediabetic and diabetic glucose ranges [1], though other researchers questioned how well those patterns generalize [2]. Reference data from healthy adults show glucose stays between 70 and 140 mg/dL (3.9 to 7.8 mmol/L)3.9 to 7.8 mmol/L (70 and 140 mg/dL) about 96% of the time [3].
Whether wearing one improves health in people without diabetes is not established. A meta-analysis of 25 trials, mostly in people with diabetes, found a modest fall in HbA1c and no clear effect on weight [4]. A 2026 review of adults without diabetes found some dietary changes but low-certainty evidence and no proven stand-alone benefit [5].
Personal food rankings may not be reliable. The same meal eaten twice gave very different readings in the same person [6], and sensors read higher than fingertip blood after meals, by different amounts in different people [7].
Safety
- The main side effects are skin irritation or rash from the adhesive, and minor bleeding at insertion.
- Readings lag blood glucose and can read high after meals, so a single spike is not a diagnosis. Diabetes is diagnosed with lab tests such as HbA1c.
- Over-the-counter sensors are cleared for adults who do not use insulin and are not built to warn of dangerous lows.
- Constant tracking can feed food anxiety in some people, especially with a history of disordered eating.
Common questions
Does Peter Attia wear a CGM?
Yes. He has worn one for years to see how food, exercise and poor sleep move his glucose. He calls it a useful tool rather than a necessity and does not say everyone needs one.
Should people without diabetes wear a CGM?
There is no proof that it improves health on its own. It can show patterns and prompt changes, but readings vary from meal to meal, so decisions based on single spikes may mislead.
Can I buy a CGM without a prescription?
In the US, yes. The FDA cleared the first over-the-counter CGM, Dexcom's Stelo, in March 2024 for adults who do not use insulin.
What are normal CGM readings without diabetes?
In healthy adults, average sensor glucose was about 98 to 104 mg/dL (5.4 to 5.8 mmol/L)5.4 to 5.8 mmol/L (98 to 104 mg/dL), and readings stayed between 70 and 140 mg/dL about 96% of the time.
Does Casey Means wear a CGM?
Yes, at least through 2021, when she said she had worn one continuously for about a year and a half. She co-founded Levels, which sells a CGM program, so she has a financial interest in the devices.
Sources
- 1.Hall H, Perelman D, Breschi A, et al. Glucotypes reveal new patterns of glucose dysregulation. PLoS Biol, 2018. doi:10.1371/journal.pbio.2005143
- 2.Hulman A, Foreman YD, Brouwers MCGJ, et al. Towards precision medicine in diabetes? A critical review of glucotypes. PLoS Biol, 2021. doi:10.1371/journal.pbio.3000890
- 3.Shah VN, DuBose SN, Li Z, et al. Continuous Glucose Monitoring Profiles in Healthy Nondiabetic Participants: A Multicenter Prospective Study. J Clin Endocrinol Metab, 2019. doi:10.1210/jc.2018-02763
- 4.Richardson KM, Jospe MR, Bohlen LC, et al. 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. Int J Behav Nutr Phys Act, 2024. doi:10.1186/s12966-024-01692-6
- 5.Makkena HB, Nimmagadda Y, Boinapelly N, et al. Behavioral and Psychosocial Effects of Participant-Visible Continuous Glucose Monitoring in Adults Without Diabetes: A Systematic Review. Medicina (Kaunas), 2026. doi:10.3390/medicina62091814
- 6.Hengist A, Ong JA, McNeel K, Guo J, Hall KD. Imprecision nutrition? Intraindividual variability of glucose responses to duplicate presented meals in adults without diabetes. Am J Clin Nutr, 2025. doi:10.1016/j.ajcnut.2024.10.007
- 7.Hutchins KM, Betts JA, Thompson D, et al. Continuous glucose monitor overestimates glycemia, with the magnitude of bias varying by postprandial test and individual - a randomized crossover trial. Am J Clin Nutr, 2025. doi:10.1016/j.ajcnut.2025.02.024
- 8.US Food and Drug Administration. FDA Clears First Over-the-Counter Continuous Glucose Monitor. FDA, 2024. Link