Oura Ring and Dexcom aren’t competitors they’re strategic partners. Dexcom, the continuous glucose monitor (CGM) company, invested $75 million in Oura in November 2024 as part of a broader partnership that lets Dexcom’s glucose data flow into the Oura app alongside Oura’s own sleep, activity, and heart rate data. The Oura Ring doesn’t measure glucose on its own it only displays it if you’re separately wearing a compatible Dexcom sensor.
This page covers what the partnership actually does, what it doesn’t do, and since this is a sizing-focused resource — how ring fit still factors into the picture if you’re using both devices together.
This page is for general information only and is not medical advice. Continuous glucose monitors are medical devices; consult a healthcare provider before using one, and never make medication, insulin, or treatment decisions based on wearable or app data alone.
Quick Overview
| Dexcom | Oura Ring | |
| What it is | A continuous glucose monitor (CGM), an adhesive skin sensor | A smart ring tracking sleep, activity, temperature, and heart data |
| Worn on | Upper arm or abdomen, via adhesive patch | Finger |
| Sizing involved | None — one-size adhesive sensor | Yes — fixed-size ring, sizing kit required |
| Regulatory status | Medical device (prescription or OTC depending on model) | Consumer wellness device |
| Relationship | Strategic partner — data integrates with Oura | Strategic partner — data integrates with Dexcom |
What the Partnership Actually Includes
Dexcom makes continuous glucose monitors — small adhesive sensors worn on the upper arm or abdomen that track glucose levels throughout the day, including its Dexcom G6 and G7 systems and Stelo, an over-the-counter sensor designed for people who don’t use insulin. Oura Ring tracks a separate set of biometrics: sleep stages, temperature trends, heart rate, activity, and more.
The partnership connects the two data sets. Someone wearing both a compatible Dexcom sensor and an Oura Ring can see glucose readings alongside Oura’s existing metrics, with the goal of showing how factors like sleep quality or the timing of a meal relate to glucose patterns over the following hours.
What It Doesn’t Do
The Oura Ring itself has no glucose sensor and cannot estimate glucose independently — every glucose number displayed through the integration originates from a separate Dexcom device you’re wearing at the same time. Oura is not a replacement for a CGM, and a CGM is not a replacement for the biometrics Oura already tracks; the partnership is additive, not a merger of the two devices into one.
It’s also worth being precise about access: Dexcom’s sensors are medical devices. Some models require a prescription, while Stelo is available over the counter, but none of them are something you get simply by owning an Oura Ring — the ring and the sensor remain two separate purchases from two separate companies.
If You’re Using Both, Ring Fit Still Matters
Oura’s contribution to this combined picture — sleep, temperature, heart rate, activity — depends on the ring making consistent skin contact, the same as it would on its own. A loose or overly tight Oura Ring produces less reliable data regardless of whether you’re also wearing a CGM, which means getting the sizing right isn’t optional just because glucose is being tracked by a separate device.
Oura Ring 5 covers US sizes 6 through 13; Oura Ring 4 extends further, from 4 to 15.
Use our ring size calculator for a fast estimate, check our Oura Ring size chart for exact millimeter equivalents, or print our free printable ring sizer if you’d rather measure at home before ordering a kit.
Frequently Asked Questions
Does the Oura Ring measure glucose?
No. The Oura Ring has no glucose sensor. Glucose data shown in the Oura app comes entirely from a separately worn, compatible Dexcom continuous glucose monitor, connected through the two companies’ data integration.
Do I need a prescription for a Dexcom sensor to use with Oura?
It depends on the model. Some Dexcom systems require a prescription, while Stelo is available over the counter for adults who don’t use insulin. Either way, the sensor is a separate purchase from the Oura Ring — check current requirements directly with Dexcom or a healthcare provider before purchasing.
Is Dexcom now owned by Oura, or vice versa?
No. The two remain separate, independent companies. Dexcom made a $75 million strategic investment in Oura’s Series D funding round as part of announcing the partnership, but neither company owns or has acquired the other.
Does wearing a Dexcom sensor change how I should size my Oura Ring?
No. The two devices are worn in completely different locations — Dexcom on the arm or abdomen, Oura on the finger — so sizing your Oura Ring works exactly the same whether or not you’re also wearing a CGM.
