The Stelo glucose biosensor is Dexcom’s over-the-counter continuous glucose monitor, the first OTC CGM cleared by the FDA in March 2024. It uses a glucose-oxidase enzyme biosensor to measure your glucose every 15 minutes for up to 15 days, streaming data to a smartphone app. Stelo is designed for adults 18 and older who are not using insulin.
How the Stelo Biosensor Works
Continuous glucose monitors like Stelo measure glucose in your interstitial fluid — the thin layer of fluid between cells just under the skin. Interstitial glucose tracks blood glucose with a short lag (typically 5-15 minutes).
Inside the Stelo filament is an enzyme called glucose oxidase. When glucose molecules contact this enzyme, a chemical reaction produces hydrogen peroxide, which generates a tiny electrical current measured by the sensor. The current is converted to a glucose reading in mg/dL and transmitted every 15 minutes to your smartphone via Bluetooth Low Energy.
According to a review in Sensors, enzyme-based biosensors like the one in Stelo have been the gold standard of CGM technology for more than 20 years because of their accuracy, stability, and small form factor.
Anatomy of the Stelo Biosensor
- Filament: A soft, flexible wire about the thickness of a human hair, inserted just 4-5 mm under the skin
- Enzyme coating: Glucose oxidase that reacts with glucose to generate an electrical signal
- Electronics pod: Contains the battery, Bluetooth chip, and analog-to-digital converter
- Adhesive patch: Holds the sensor in place on your upper arm for up to 15 days
- Applicator: A spring-loaded button-push device that inserts the filament quickly and nearly painlessly
Stelo Biosensor Specs and Comparison
| Feature | Stelo Biosensor | Dexcom G7 | FreeStyle Libre 3 |
|---|---|---|---|
| Wear time | 15 days | 10.5 days | 14 days |
| Warm-up time | 30 minutes | 30 minutes | 60 minutes |
| Reading frequency | Every 15 minutes | Every 5 minutes | Every 1 minute |
| MARD | ~10% | 8.2% | 7.9% |
| Wear site | Back of upper arm | Back of upper arm | Back of upper arm |
| Water resistance | Yes (IP28) | Yes (IP28) | Yes (IP27) |
Who Should Use the Stelo Biosensor?
The FDA cleared Stelo for adults 18 and older who:
- Have type 2 diabetes and are not on insulin
- Have prediabetes and want to understand meal responses
- Are health-focused and want to see how food and lifestyle affect glucose
It is not for type 1 diabetes, anyone on insulin, pregnant women, or people with a history of severe hypoglycemia. These users need a prescription CGM with dose-informing accuracy.
Using the Stelo Biosensor Day to Day
The Stelo app displays a live trend line, daily glucose summary, and time-in-range metrics. Common use patterns include:
- Checking post-meal glucose to see which foods spike you hardest
- Timing a 10-minute walk after meals to blunt glucose rises
- Comparing days with good vs. poor sleep
- Tracking alcohol or stress effects
- Sharing data with a primary care doctor or dietitian
Learn more about building an effective eating plan in our diet and nutrition hub.
Accuracy and Limitations
Stelo has a MARD of approximately 10%, which is clinically accurate for trend monitoring but less precise than prescription CGMs designed for insulin dosing. Because it reads every 15 minutes (vs. every 5 for the G7), you may miss very rapid glucose swings. Certain medications (acetaminophen at high doses, hydroxyurea) and extreme dehydration can temporarily affect readings.
The Stelo app does not include urgent-low alerts or share-with-follower features found in the G7, since it is not intended for emergency treatment decisions.
Cost and Purchasing
Stelo is sold directly at Stelo.com and through select pharmacies. Pricing as of 2024:
- One sensor (15 days): $89
- Monthly subscription (2 sensors, one-month supply): ~$99
Because Stelo is an OTC wellness product, most insurance plans do not cover it, but HSA and FSA funds often can be used. A healthcare provider’s receipt of medical necessity may help with FSA claims.
What Stelo Teaches About Prediabetes
For people with prediabetes, seeing real-time glucose data can drive dramatic behavior change. Many users learn, for example, that adding protein to breakfast flattens their morning spike, or that an after-dinner walk lowers post-meal glucose by 20-40 mg/dL. Check our A1C levels guide to put your Stelo readings in context with long-term metrics.
The Bottom Line
The Stelo glucose biosensor is a small, 15-day continuous glucose monitor that uses enzyme-based sensing technology to track glucose every 15 minutes. Cleared by the FDA in 2024 as the first OTC CGM in the United States, Stelo is aimed at adults not using insulin — especially those with type 2 diabetes on oral medications, prediabetes, or wellness goals. Talk to your doctor about how to interpret your Stelo data and whether lifestyle or medication adjustments are warranted.
