Do You Need a Continuous Glucose Monitor If You're Not Diabetic?

I assumed I'd already be wearing one.

I track my macros to the gram. I know my fasting window to the quarter hour. I run a keto practice specifically because I want to keep my blood sugar out of the ditch, and I lead engineering teams for a living, which means my entire professional instinct is: if it matters, you instrument it. A glucose sensor that streams a number to your phone every few minutes seemed like the obvious next dashboard panel. Half the health accounts I follow are wearing one. So are two people on my own team, unprompted, because a coworker mentioned it in a Slack thread and it spread the way these things spread now.

But my day job carries a rule that never makes it into the wellness marketing: you don't add an alert to a dashboard unless you already know what you'll do the moment it fires. A panel that just produces a number, with no agreed threshold and no action behind it, isn't monitoring. It's noise with a timestamp.

So before I strapped anything to my arm, I wanted the trial that tells a healthy person what to do with the number. I expected that to take an evening.

It took most of a weekend, and what I found is stranger than either side of the current argument. The research is real, it supports exactly one narrow use, and it comes with a guidance vacuum that the industry selling these devices has almost no incentive to point out.

What You Can Actually Buy Now

Until recently, a continuous glucose monitor meant a prescription, a diabetes diagnosis, and a device covered — or not — by insurance. That changed. Dexcom's Stelo, Abbott's Lingo, and a handful of competitors are now cleared for over-the-counter sale in the United States to adults without diabetes. No prescription, no doctor's visit, roughly forty to a hundred dollars a month depending on the brand and the subscription tier. A small adhesive sensor sits on the back of your arm for about two weeks, reads glucose from the interstitial fluid under your skin, and streams a live number to an app.

Here is the detail that gets lost in every review roundup: FDA clearance for over-the-counter sale is a safety and accuracy bar. It is not a proof-of-benefit bar. The agency confirmed these sensors measure glucose reasonably well against a fingerstick reference. It did not require anyone to show that wearing one makes a healthy person's health outcomes any better. Clearance to sell and evidence of benefit are two different findings, and the marketing leans hard on the first one while quietly borrowing the credibility of the second.

That distinction matters more here than it does for most wearables, because a glucose sensor doesn't just log a data point — it hands you a live number that looks clinical, formatted the same way a hospital monitor formats one, with the same implied authority. A step counter undercounting your walk by 8% doesn't change how you feel about your body. A glucose number that reads "high" does, whether or not "high" means anything for you specifically. The device borrows medical-grade presentation for a use case medicine hasn't actually validated yet.

What "Normal" Even Looks Like

Before you can judge your own number, you need to know what a healthy person's number actually looks like — and until fairly recently, nobody had pinned that down under controlled conditions. Diabetes care has decades of validated targets. Wellness use has almost none.

The closest thing to a real answer came from a small exploratory trial published in PLOS Digital Health, which put continuous monitors on ten healthy adults, ages eighteen to forty, for fourteen days and ran them through standardized food challenges, two exercise sessions, and a deliberate stress test. The reference numbers it produced: mean daytime glucose of 107.6 mg/dL, a coefficient of variation around 17%, and 96% of all time spent in the 70–140 mg/dL range — comfortably above the 70% time-in-range target used to manage actual diabetes. Nobody in the trial had a single hypoglycemic episode.

That is a genuinely useful data point. It is also, on its own terms, thin — ten people, fourteen days, one small trial. And even inside that tight group, the individual spread was wide. The same bout of anaerobic exercise produced an average glucose swing of about 29 mg/dL, but the spread around that average was almost as large as the average itself — meaning two healthy people doing the identical workout can produce visibly different graphs, and neither one is doing anything wrong. Carbohydrate-heavy meals produced the highest peaks, unsurprisingly, but even there the range between individuals was substantial.

Now pair that with the second half of the problem: no major professional body has weighed in on what any of this should mean for someone without diabetes. I went through the current position statements — the American Diabetes Association, the Endocrine Society, the American Association of Clinical Endocrinology — and every one of them is scoped entirely to people already diagnosed with type 1 or type 2 diabetes. None sets a target range, a variability threshold, or an action plan for a healthy person's CGM data. That isn't an oversight. It's an honest reflection of how little has been established.

A wearable can hand you a number. It cannot hand you the guideline that tells you what the number means. For a healthy person, that guideline doesn't exist yet.

The One Thing the Evidence Actually Supports

I did find a real, replicated, well-evidenced use for a CGM in someone without diabetes. It's narrower than the marketing suggests, and it has nothing to do with wearing the thing indefinitely.

A 2025 systematic review in the journal Cureus pooled seven studies — a mix of randomized trials and observational work — looking specifically at CGM use in non-diabetic people for cardiovascular prevention. Its clearest, most consistent finding was that a CGM is genuinely good at personalizing when you move relative to a meal. When participants timed a walk to start right before their own individual post-meal glucose peak, the result was a significant drop in postprandial glucose, insulin, and C-peptide.

A tightly controlled trial published the same year in Scientific Reports put a number on that effect. Twelve healthy young adults did a randomized crossover trial: a 75-gram glucose drink, then either sitting, a ten-minute walk starting immediately, or a thirty-minute walk starting half an hour later. The ten-minute immediate walk dropped peak glucose to 164.3 mg/dL versus 181.9 mg/dL for sitting — roughly 10% lower, and statistically significant (p = 0.028). The two-hour glucose exposure and the average glucose over the test both dropped by similar, significant margins.

That's a real, well-controlled result. It is also a small one to lean on — twelve people, all young and healthy, drinking a lab beverage rather than eating an actual dinner. The authors say as much themselves: the sample restricts how far you can generalize, and a sugar drink "may not adequately reflect physiological postprandial glycemic responses compared with real meals." I'm not going to pretend a twelve-person trial with a glucose shot settles the question. But paired with the broader Cureus review, it's the most consistent, most mechanistically sensible finding in this entire literature — and it's honest about the fact that even this evidence has never been shown to move a hard outcome. The Cureus authors are direct about it: "evidence of a direct impact on hard cardiovascular endpoints remains limited." Nobody has shown that walking after meals because a sensor told you to changes your actual heart disease risk. What's shown is that it changes the shape of one afternoon's glucose curve.

What It Cannot Tell You

This is the part that matters most, and it's the part the product pages skip.

No randomized trial has tested whether a healthy person who wears a CGM long-term ends up with any better hard outcome — not weight, not a healthier HbA1c trajectory years later, not fewer cardiovascular events. Michael Fang, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health, put it plainly in a 2026 piece examining exactly this question: "In people without diabetes, we don't really know how to act on differing glucose patterns," and, more bluntly, "no major clinical trials have attempted to demonstrate these types of benefits." That's not evidence of absence. It's an honest description of a research base that hasn't been built yet, running well behind a consumer market that already exists.

A single elevated reading also doesn't tell you whether the swap you're making is actually a healthier one. Johns Hopkins diabetes researcher Elizabeth Selvin makes a version of this point that I found genuinely clarifying: glucose is one number among many that matter, and chasing it in isolation can push you toward a food swap — trading a piece of fruit for a processed meat that barely moves the needle — that looks like a win on the graph and isn't obviously one for your health overall. Her recommendation, and I think it's the right one: "regular screening using lab tests such as glucose and HbA1c is still the best way to understand risk." Those tests have decades of validated cutoffs behind them. A fourteen-day sensor snapshot does not.

The Data You Didn't Ask For

There's a cost to this that almost never shows up in a product review, and it's the one I take most seriously.

A 2025 mixed-methods study in Obesity Research & Clinical Practice surveyed fifty-six adults without insulin-dependent diabetes who'd used a CGM in the past year. Eighty-nine percent said it helped them adopt healthier diet and activity habits — a real, meaningful number. But 68% also reported fear of developing type 2 diabetes after seeing a single elevated reading, and the distress was significantly worse in younger adults and in people with obesity. Distress specifically about the device's appearance on their body correlated with existing eating-disorder symptoms.

The finding I keep coming back to is that the benefit and the harm weren't showing up in two separate groups of people. They were frequently the same people. The exact mechanism that nudges someone toward a better dinner choice is, structurally, the same mechanism that can tip a vulnerable person into obsessive tracking. That's not a reason to dismiss the device. It's a reason to take seriously that "just strap it on and see" is not a neutral instruction.

This is where my day job actually has something to say. Every platform team I've run has the same rule about telemetry: you don't wire up a panel or a page-worthy alert unless you already know the runbook — the specific action a person takes the moment that number crosses a line. An alert with no action behind it isn't information. It's anxiety with a timestamp, and it trains whoever's on call to either ignore real signals or panic at noise, with no way to tell which one they're doing in the moment. A glucose sensor handed to a healthy person, with no agreed target range and no clinical runbook behind most of what it shows you, is the exact same failure mode wearing a different industry's clothes. Good observability was never "monitor everything you can." It's monitoring the handful of things you've already decided you will act on — and being honest that everything else is just noise you're paying to look at.

An alert with no action behind it isn't information. It's anxiety with a timestamp. The best engineering teams I've led know the difference. Most CGM marketing does not.

Who This Is Actually For

Strip away the marketing and three honest categories are left.

People with diagnosed prediabetes or established insulin resistance, wearing a CGM as part of an actual care plan with a clinician — a different population than this article, with a different and stronger evidence base behind it. That's a legitimate medical use case and it isn't what I'm weighing here.

People running a genuinely bounded experiment: a specific question — does my after-dinner walk change my numbers, does my usual breakfast spike more than I'd guess — a two-to-four-week window, and then the sensor comes off. This is the one use the evidence actually supports, and it's worth doing if the question is real to you.

And then most healthy forty-something adults, for whom the honest answer is: you're probably better served by what already has decades of validated reference ranges behind it. A fasting glucose and an HbA1c at your annual physical costs a fraction of a CGM subscription, comes with an actual clinical target, and doesn't hand you two thousand unexplained data points a month to self-diagnose. If you're already eating low-carb for other reasons, as I am, a CGM is even less likely to tell you something new — it will mostly confirm what the diet is already doing, at a real monthly cost, with a real chance of turning a neutral number into a source of dread.