The Stelo biosensor is an over-the-counter glucose biosensor from Dexcom, cleared by the FDA in March 2024. Worn on the back of the upper arm for 15 days, it delivers continuous glucose readings every 15 minutes to a smartphone app and is designed for adults 18 and older who are not using insulin.
What a Glucose Biosensor Is
A biosensor combines a biological recognition element — typically an enzyme or antibody — with an electronic transducer that converts the biological reaction into a measurable signal. In Stelo, a filament coated with glucose oxidase sits just under the skin. When glucose reacts with the enzyme, it produces a tiny electrical current that scales with glucose concentration, and the sensor’s electronics convert that current into a mg/dL value.
How Stelo Compares to a Traditional CGM
Stelo is technically a continuous glucose monitor, but Dexcom markets it as a biosensor to distinguish it from prescription CGMs. According to the FDA clearance, Stelo is specifically intended for “adults with type 2 diabetes not on insulin or those who want to better understand how diet and exercise may impact blood sugar.”
Accuracy
Stelo uses the same sensor platform as Dexcom G7, which has published accuracy data around 8-9% MARD (mean absolute relative difference) compared to a laboratory reference. This is among the best in the CGM category. However, like all CGMs, accuracy is lower during rapid glucose changes, in the first day of wear, and at very low or very high glucose values.
Stelo vs. Other Glucose Sensors
| Feature | Stelo Biosensor | Dexcom G7 | FreeStyle Libre Rio |
|---|---|---|---|
| Prescription required | No | Yes | No |
| Wear time | 15 days | 10 days + 12 hr | 15 days |
| Reading frequency | 15 min | 5 min | 1 min |
| Urgent alerts | No | Yes | No |
| MARD | ~8-9% | ~8.2% | ~9% |
| App compatible | iOS, Android | iOS, Android, Watch | iOS, Android |
Who Stelo Is For
- Adults with prediabetes looking to see how specific foods affect their glucose
- Type 2 diabetes users on metformin or lifestyle alone who want more than a quarterly A1C test
- Anyone interested in learning how sleep, stress, and exercise move their glucose
Who Should Not Use Stelo
- Anyone using insulin — urgent low alerts are essential and Stelo does not provide them
- People with a history of severe hypoglycemia
- Pregnant users (the sensor is not cleared for pregnancy)
- Patients on dialysis or who are critically ill
What You See in the Stelo App
The Stelo app shows your current glucose, a daily glucose curve, average daily values, time spent in a “healthy range,” and post-meal spike notifications. It also provides weekly summaries and educational tips to help you recognize patterns. The data can be exported to share with your clinician.
Tips for Maximum Value
- Log the meals that produce the largest post-meal spikes
- Test identical foods at different times of day to spot timing effects
- Walk for 10-15 minutes after dinner and compare the glucose curve
- Track how poor sleep affects morning fasting values
Our diet and nutrition hub lists foods that tend to produce flatter glucose curves.
Cost and Access
Stelo sells directly from Dexcom online for about $99 for a 2-sensor (30-day) kit or $89/month with a subscription. Because it is OTC, insurance coverage is rare, but HSA and FSA accounts often accept it.
What Research Says About OTC CGMs
Early studies on CGM use in people without diabetes or with prediabetes have shown improvements in dietary choices, weight, and fasting glucose over 3-6 months of wear. Participants report becoming more aware of meal composition effects and more willing to add post-meal walks. However, researchers caution against overinterpreting normal variation — short glucose spikes in metabolically healthy people are expected and not harmful. The value is in spotting patterns that point to early insulin resistance, not in chasing a perfectly flat line.
Where Stelo Fits Alongside A1C
A1C remains the gold-standard test for long-term glucose control because it reflects average glucose over about three months. Stelo complements A1C by showing how you got to that number — which meals, which times of day, and which habits shaped your average. Many clinicians now recommend a CGM trial of 2-4 weeks before making lifestyle or medication changes, using the pattern it reveals to tailor advice rather than relying on generic guidance.
The Bottom Line
The Stelo biosensor is a landmark product — the first FDA-cleared OTC CGM in the US. It makes continuous glucose data available to tens of millions of Americans with prediabetes or type 2 diabetes who previously had no access. Accuracy is high, wear time is generous, and the app is designed around lifestyle learning rather than insulin dosing. If you use insulin, stick with a prescription CGM that offers urgent alerts.
Medical disclaimer: This article is for educational purposes and is not medical advice. Consult your healthcare provider about integrating CGM data into your diabetes management.
