How to Get a Glucose Monitor: Prescription or OTC

Most glucose monitors in the United States still require a prescription, but the landscape shifted in 2024 when the FDA approved the first over-the-counter continuous glucose monitor. Whether you need a doctor’s sign-off depends on the type of device you want, whether you use insulin, and how you plan to pay for it. The distinction between prescription and OTC is less straightforward than it sounds, because insurance coverage, device type, and your specific health situation all factor into the best path forward.

The First Over-the-Counter Continuous Glucose Monitor

In March 2024, the FDA cleared the Dexcom Stelo Glucose Biosensor System as the first continuous glucose monitor (CGM) available without a prescription in the United States. The device is intended for adults 18 and older who do not use insulin, including people managing type 2 diabetes with oral medications or lifestyle changes, and people with prediabetes who want to track their glucose patterns.¹ Shortly after, Abbott followed with an OTC version of its Libre system. These devices are sold directly to consumers at pharmacies and online, no doctor visit required.

Traditional finger-prick blood glucose meters, by contrast, have been available without a prescription for decades. You can walk into most pharmacies and buy a basic glucometer and test strips off the shelf. These are cheap, well-understood devices. But the newer CGM systems represent a different category of technology altogether: instead of a single snapshot from a drop of blood, they use a tiny sensor inserted just under the skin to measure glucose in the fluid between your cells, delivering readings every few minutes around the clock.

Who Still Needs a Prescription

The OTC clearance applies only to specific CGM models designed for non-insulin users. If you use insulin to manage type 1 or type 2 diabetes, the CGMs intended for you remain prescription-only. Devices like the Dexcom G7, Abbott FreeStyle Libre 3, and the Medtronic Guardian system are classified as prescription medical devices because they are often integrated with insulin dosing decisions. Using a CGM to calculate an insulin dose carries real risk if the device malfunctions or readings are off, so the FDA maintains tighter oversight for that use case.

There is also a practical insurance consideration. Even if an OTC CGM would technically work for you, most health insurance plans and Medicare only cover CGMs that are prescribed by a physician and deemed medically necessary. If you want your insurance to help pay, you will almost certainly need a prescription regardless of whether the device itself could be purchased without one. So for many people with diabetes, the prescription route is not just a regulatory requirement but a financial one.

What CGMs Measure and Why It Matters

A CGM does not measure blood glucose directly. Its sensor sits in the interstitial fluid just beneath the skin and measures glucose there. Because glucose has to travel from your bloodstream into that fluid, there is a built-in delay. Direct measurements in healthy adults have clocked this lag at roughly five to six minutes under fasting conditions.² In practice, this means a CGM reading reflects where your blood sugar was a few minutes ago, not where it is right now. During rapid changes like after a meal or intense exercise, the gap between the CGM number and your actual blood glucose can widen.

For most everyday monitoring, this lag is small enough to be clinically irrelevant. But if you are making time-sensitive decisions about insulin dosing, especially during hypoglycemia, the delay can matter. This is one reason the FDA draws a line between CGMs for insulin users and those for everyone else. The OTC devices are designed for trend-watching and pattern recognition, not for split-second treatment decisions.

How Accurate Are Current Devices

CGM accuracy is typically measured using a metric called mean absolute relative difference, which tells you, on average, how far off the sensor reading is from a lab-quality blood glucose measurement. Lower numbers are better. A head-to-head comparison of two widely used systems found the FreeStyle Libre 3 had readings that deviated from reference values by about 9% on average, while the Dexcom G7 deviated by about 14%.³ Both are considered clinically acceptable, but the difference is noticeable. Neither system is as precise as a laboratory blood draw, and individual sensors can have good days and bad days.

Certain medications and substances can also throw off CGM readings. A pilot study found that acetaminophen (Tylenol), the blood pressure drug lisinopril, albuterol inhalers, and even red wine appeared to interfere with some CGM devices.⁴ The degree of interference varies by device. Testing on a different sensor system (the Eversense implantable CGM) found that acetaminophen did not produce clinically meaningful errors at normal doses, though tetracycline and mannitol did.⁵ If you take medications regularly, it is worth knowing that your readings could be slightly skewed, and checking with the manufacturer’s documentation for your specific device.

Insurance, Medicare, and Out-of-Pocket Costs

CGMs are not cheap. Without insurance, a month’s supply of sensors typically runs between $75 and $150, depending on the brand and where you buy them. OTC devices tend to sit at the higher end of that range because there is no insurance discount applied at the point of sale. For people who go the prescription route and have coverage, copays vary enormously by plan, but many commercial insurers now cover CGMs for insulin-dependent patients, and Medicare has expanded coverage in recent years.

From a health-system perspective, CGMs appear to be a reasonable investment. A cost analysis from the Medicare perspective found that continuous monitoring cost about $7,000 more in direct medical costs over a long time horizon compared to traditional finger-prick testing, but produced meaningfully better health outcomes. The incremental cost worked out to roughly $9,300 per quality-adjusted life year gained, well below the threshold that health economists generally consider cost-effective.⁶ That calculation matters because it strengthens the case for broader insurance coverage going forward, though it does not help much if you are paying cash today.

If you are uninsured or underinsured and have diabetes, the prescription path is still usually worth pursuing. Many manufacturers run patient assistance programs, and a prescription opens the door to discount cards and copay programs that are not available for OTC purchases. For someone without diabetes who is simply curious about their glucose trends, the OTC option is the only realistic path, since insurers have no reason to cover a device for a condition you do not have.

Do CGMs Actually Improve Health Outcomes

The evidence for CGMs in people with type 2 diabetes is solid and growing. A meta-analysis of randomized controlled trials in people with type 2 diabetes found that CGM use reduced HbA1c (a marker of average blood sugar over two to three months) by about 0.37 percentage points compared to standard monitoring.⁷ A separate meta-analysis focused specifically on non-insulin users found a nearly identical reduction in HbA1c, along with increased time spent in the target glucose range and less time spent above it.⁸ A 0.37-point HbA1c drop may sound modest, but sustained over years it is associated with real reductions in diabetes complications.

The benefit is clearest in people who are actually managing a metabolic condition. For healthy individuals with normal glucose regulation, the picture is different, which is an important distinction given the growing wellness-market interest in CGMs.

CGMs for People Without Diabetes

A fast-growing segment of CGM buyers are people without diabetes who want to “optimize” their metabolic health, often encouraged by wellness influencers and biohacking communities. The OTC availability of devices like the Stelo has made this easier than ever. But the evidence for benefit in this group is thin.

A systematic review of CGM use in non-diabetic populations found that CGMs did help lower mean blood glucose in people with prediabetes, but showed no appreciable glycemic benefit in people who already had normal glucose levels.⁹ There was also no significant effect on body weight. Where CGMs did seem useful for non-diabetic people was in guiding specific behavioral changes, like timing a walk after meals to blunt glucose spikes.¹⁰

The distinction between prediabetes and normal glucose regulation is relevant here. A matched comparison found that people with prediabetes spent less time in the target range, had higher mean glucose readings, and showed greater glucose variability compared to normoglycemic individuals, even though both groups would typically feel fine and have no symptoms.¹¹ If you have prediabetes and want to see how your body responds to meals and exercise in real time, an OTC CGM can be a genuinely useful tool. If your glucose is already normal, you are likely paying $100 or more a month to watch numbers that barely move.

How Wearing a CGM Changes Behavior

One of the more compelling arguments for CGMs, especially for people who do not use insulin, is the behavioral feedback loop. Seeing your glucose spike after a bowl of rice hits differently than reading a pamphlet about glycemic index. A meta-analysis of studies in people with diabetes found that CGM users added about 16 extra minutes of physical activity per day and cut their daily calorie intake by roughly 70 calories compared to control groups. Carbohydrate intake dropped by about 20 grams per day.¹² These are modest changes individually, but compounded over months they can add up.

The evidence is not entirely consistent, though. A separate meta-analysis found that while CGM users shifted their diet toward fewer carbohydrates, total calorie intake and physical activity levels did not always change significantly.¹³ The dietary effects seem more reliable than the exercise effects, which makes intuitive sense: seeing a glucose spike after a specific food is immediate and actionable feedback, while exercise effects on glucose are more diffuse and delayed.

The Psychological Side of Constant Monitoring

Strapping a sensor to your arm and watching glucose numbers stream to your phone all day can be motivating, but it can also be anxiety-inducing. A study of adults using CGMs found that distress levels varied widely, but more than two-thirds of participants reported feeling afraid of developing type 2 diabetes when they saw high glucose readings, regardless of whether they actually had diabetes.¹⁴ Younger people and those with obesity experienced greater distress. People with higher levels of eating disorder symptoms were more bothered by the device’s physical appearance on their body.

This is worth thinking about before you buy. If you have a history of anxious health monitoring or disordered eating, constant glucose data may do more harm than good. A normal postprandial glucose spike can look alarming on a graph if you do not know what a normal spike looks like, and the temptation to restrict food to keep the line flat can feed unhealthy patterns. For many people, CGMs are empowering. But they are not psychologically neutral.

Skin Reactions and Wear Comfort

CGM sensors attach to the skin with adhesive patches, and roughly one in four users develops some kind of skin reaction. A study of over 850 patients found that 28% of CGM users reported skin issues, most commonly redness and itching at the sensor site.¹⁵ Pain occurred in about a quarter of those with reactions, and blistering or peeling in a smaller fraction. Most of these reactions appeared to be irritation from the adhesive rather than true allergies, though genuine allergic contact dermatitis does occur. The most common culprit allergens are acrylate chemicals in the adhesives, particularly isobornyl acrylate.¹⁶

The good news is that reactions rarely forced people to stop using the device entirely. Only about 3% of all CGM users in that study permanently discontinued use because of skin problems. Barrier films, hydrocolloid patches placed under the sensor, and rotating insertion sites can help. If you develop persistent blistering or spreading redness, that warrants a conversation with a dermatologist, because true allergic reactions tend to worsen with repeated exposure.

Data Privacy With Connected Devices

Modern CGMs are connected devices. They transmit glucose data via Bluetooth to a smartphone app, which may sync to a cloud server where the data can be shared with your doctor, a caregiver, or a third-party wellness platform. This raises real privacy concerns. An analysis of the data ecosystem around CGMs found that patients have very little control over how their glucose data is collected, stored, and used, and that existing privacy protections are not robust enough to address the risks.¹⁷

For OTC devices, this concern may be amplified because the purchase is disconnected from a healthcare provider relationship. When a CGM is prescribed and used within a clinical context, the data typically falls under health privacy laws. When you buy one off the shelf and pair it with an app, the data may be governed by the app’s terms of service instead, which can be far less protective. If data privacy matters to you, read the app’s privacy policy before you buy, and pay attention to whether the manufacturer shares aggregated or de-identified data with third parties.

The Environmental Footprint of Disposable Sensors

Each CGM sensor is a small piece of electronics with a battery, a circuit board, and a plastic housing, designed to be worn for one to two weeks and then thrown away. At the scale the industry has now reached, that adds up fast. A quantification study estimated that the widespread use of CGM systems generates hundreds of tons of plastic waste and electronic waste, plus thousands of tons of packaging and applicators, every year.¹⁸ The batteries in particular are a concern because they contain materials that do not belong in landfills.

No major CGM manufacturer currently runs a consumer-facing recycling program for used sensors, though some pilot efforts exist. The implantable Eversense system, which lasts several months per sensor, produces less waste per unit of monitoring time, but it requires a minor procedure for insertion and removal and remains prescription-only. For the foreseeable future, if you use a CGM, you are generating a steady stream of small electronic waste. This is not a reason to avoid a device that genuinely helps manage your health, but it is a cost that rarely appears in the marketing materials.