Continuous glucose monitors were a closely guarded category for two decades, prescribed only to people with diabetes (mostly type 1) and tied tightly to insurance approval. That changed when the FDA cleared Dexcom Stelo in March 2024, followed by Abbott Lingo and Libre Rio in 2024 and 2025. All three are now sold over the counter to adults not using insulin, marketed primarily as wellness and metabolic-awareness tools. The technology is the same as the prescription versions in most respects, but the use case and the data interpretation are very different. This guide explains what the devices do, where they help, where the marketing overpromises, and what your doctor needs to know about your interest in the data.
What the sensor actually measures
A CGM is a small filament that sits in the interstitial fluid just under the skin, typically on the back of the upper arm. The filament uses a glucose oxidase reaction (or a fluorescence-based variant in some newer sensors) to estimate glucose concentration in the interstitial fluid. The transmitter chip on top of the skin reads the sensor and broadcasts the measurement to a phone every 1 to 5 minutes.
Critically, the sensor measures interstitial glucose, not blood glucose. Interstitial glucose lags blood glucose by 5 to 15 minutes, longer during rapid changes. Modern CGMs apply algorithms to estimate the corresponding blood glucose, but the lag is a real limitation, especially during exercise, meals, and overnight drops.
Wear time is 14 days per sensor on the OTC models. The first 12 to 24 hours of any sensor are usually the least accurate.
The three OTC players
Dexcom Stelo. Released April 2024 in the US. 15-day sensor. Reports glucose every 15 minutes (smoothed from the more frequent underlying readings). About $89 for a two-pack covering 28 days. Phone-only, no separate reader. Targeted at adults with prediabetes and type 2 diabetes not using insulin, plus general wellness users.
Abbott Lingo. Released in the US in late 2024 (UK earlier). 14-day sensor. Marketed strongly to wellness users with a glucose-spike score and lifestyle coaching content. About $49 for one sensor or $89 for a 4-week subscription.
Abbott Libre Rio. OTC version of FreeStyle Libre 3, released 2025 in the US. 14-day sensor, broadly similar accuracy to the prescription Libre 3 Plus. Marketed to non-insulin-using adults with type 2 diabetes.
The prescription Dexcom G7 and FreeStyle Libre 3 Plus remain available for insulin users and have features the OTC versions lack: hypoglycemia alarms, integration with insulin pumps, and (in some cases) better insurance coverage.
Who actually benefits
Three groups have clear use cases supported by clinical evidence:
Type 2 diabetes on oral medication or GLP-1. Studies show modest A1C improvements with CGM use in non-insulin-using type 2 patients, plus better behavioral feedback about meals and timing. The OTC devices make this access easier and cheaper for patients whose insurance has historically denied CGM coverage. Use under your doctor’s guidance.
Prediabetes. The evidence is thinner here, but feedback about meal responses can support a behavior-change program. The CGM does not diagnose or replace standard fasting glucose and A1C testing.
Gestational diabetes. Some obstetricians are starting to use OTC CGMs in pregnant patients with gestational diabetes. Treatment decisions still belong to the obstetric team.
The “wellness” use case
The wellness market is what is driving most OTC CGM sales, and the evidence here is thin.
A healthy adult typically has a fasting glucose of 70 to 99 mg/dL and post-meal peaks under 140 mg/dL. The CGM will show ranges in that area for most healthy users, with occasional excursions above 140 after high-carbohydrate or large meals. The variability is normal. It does not by itself indicate dysfunction or predict diabetes.
The behavioral observation that high-glycemic foods (white bread, sugary drinks, certain breakfast cereals) produce bigger spikes than low-glycemic foods (eggs and avocado, fiber-rich whole grains) is well-established without a CGM. Some people find the personalized feedback motivating. Others find it generates food anxiety without actionable benefit.
The American Diabetes Association does not recommend CGM use for non-diabetic adults outside of specific situations. The FDA cleared OTC CGMs as wellness devices but did not endorse their use for any specific health outcome in healthy adults.
If you are healthy and curious, a single 14-day cycle is a reasonable experiment. Long-term use without a clinical indication is harder to justify on evidence.
Reading the data sensibly
A few principles for getting useful information out of a CGM without overinterpreting:
Look at trends, not individual data points. A single 165 mg/dL reading after pasta tells you very little. A pattern of post-dinner peaks above 180 across two weeks is more informative.
Time in range matters more than the average. Most clinical research now focuses on percentage of time spent in the 70 to 180 mg/dL range. Healthy adults are typically above 96 percent. Adults with type 2 diabetes target above 70 percent.
The fasting and pre-meal readings are the most clinically meaningful. Post-meal spikes are normal and expected; the speed of return to baseline is what differentiates healthy metabolism from impaired.
Sleep glucose patterns can reveal real problems. A flat overnight glucose between 70 and 100 mg/dL is the normal pattern. Repeated nighttime spikes or unexplained drops deserve a doctor’s conversation.
Exercise lowers glucose, then sometimes raises it. Long aerobic exercise often drops glucose. Short intense exercise often raises it briefly through stress hormones. Both are normal.
The limits to keep in mind
OTC CGMs have intentional limitations compared with the prescription versions:
- No low-glucose alarms (a deliberate exclusion for safety reasons in non-insulin users)
- Different accuracy profile in the hypoglycemic range (typically less accurate below 70 mg/dL)
- Marketed and labeled as wellness, not as a diagnostic tool
- Subscription friction can interrupt continuous tracking
A CGM does not diagnose diabetes or prediabetes. Those diagnoses come from fasting plasma glucose, A1C, oral glucose tolerance tests, and your doctor’s clinical judgment. Bring CGM data to your appointments if it is informative, but do not let it replace standard testing.
Talk to your doctor first
If you have a chronic condition, are on any medication that affects glucose, are pregnant, or are using a CGM to make decisions about how you eat, talk to your doctor before drawing conclusions from the data. CGMs are powerful tools when paired with clinical context and noise when not.
Frequently asked questions
Do you need a prescription for a CGM in 2026?+
Not for the over-the-counter models. The FDA cleared Dexcom Stelo in March 2024 and Abbott Lingo and Libre Rio in 2024 and 2025 for sale without a prescription to adults who are not on insulin. Insulin-using diabetics still receive a prescription CGM (Dexcom G7, FreeStyle Libre 3 Plus) because the OTC versions intentionally omit some safety features like low-glucose alarms. Talk to your doctor about which device is right for your situation.
What does an OTC CGM cost without insurance?+
Roughly $50 to $99 for a 14-day sensor pair, depending on subscription and pharmacy. Stelo runs about $89 for two sensors (28 days of wear). Lingo runs about $49 for a single 14-day sensor or $89 for a four-week subscription. Insurance generally does not cover OTC versions because they are marketed as wellness devices, not medical devices for diagnosed conditions.
Are CGMs useful for people without diabetes?+
The honest answer is that the evidence is mixed. Healthy adults typically run blood glucose between 70 and 140 mg/dL after meals, and the spikes a CGM displays in this range usually do not predict health outcomes. Some users find behavioral value in seeing meal responses (which foods spike them, which do not), but the data does not equate to a medical diagnosis. The American Diabetes Association does not recommend CGM use for adults without diabetes or prediabetes. Discuss with your doctor before drawing conclusions.
How accurate is a CGM compared with a finger-stick blood test?+
OTC CGMs report mean absolute relative difference (MARD) of about 8 to 10 percent compared with a reference laboratory blood test. That means a true blood glucose of 100 mg/dL might be reported as anything from 90 to 110 mg/dL by the sensor. Accuracy is worse in the first day of sensor wear and during rapid glucose changes. Finger-stick meters are typically more accurate at a single moment, while CGMs trade that for continuous coverage.
Should I get a CGM to lose weight?+
Probably not as the primary tool. No good trial shows that healthy adults using a CGM lose more weight than those using standard food and activity tracking. A CGM can be useful as a short-term educational tool to see how specific foods affect your glucose, but the long-term behavior change is the same: protein, fiber, vegetables, and less ultra-processed food. Talk to your doctor or a registered dietitian about a plan that fits your situation.
Priya Sharma
Priya Sharma writes for The Tested Hub.