Best Continuous Glucose Monitors: How to Compare Your Options

The right continuous glucose monitor (CGM) depends on your health needs, insurance coverage, and phone compatibility, and the decision should be made with your healthcare provider. Key factors to compare are sensor wear time, calibration needs, alert options, accuracy information published by the maker, and how well the app works with your devices. This guide is general information, not medical advice.

What a CGM does

A continuous glucose monitor uses a small sensor, usually worn on the skin, to measure glucose in the fluid beneath it. It reports readings every few minutes to a receiver or smartphone app, often with trend arrows and alerts for highs and lows. It is different from a traditional fingerstick meter, which gives a single reading at a moment in time. Many prescription CGMs are cleared for people with diabetes, and some over-the-counter systems have been introduced for wider use; availability and clearance details change, so confirm with the manufacturer and your clinician.

Talk to your clinician first

Because a CGM informs health decisions, your care team should guide which device suits you, how to interpret readings, and what to do about alerts. Never change medication or insulin dosing solely on a device reading without guidance, and keep a backup method such as a fingerstick meter for when readings seem inconsistent with how you feel. Ask whether your plan covers a CGM, which brands it prefers, and whether a prescription is needed.

Features to compare

Compare the published accuracy information, often reported as a metric such as MARD, but remember that real-world performance varies by person, placement, and hydration. A lower number is generally better, though results from different studies are not always directly comparable.

Real-world usability

• Sensor placement: upper arm, abdomen, or other approved sites; follow the instructions for your model.
• Adhesive and skin sensitivity: some people need extra tape or skin barriers.
• Water resistance: check the manufacturer’s rating for showering and swimming.
• Interferences: some medications or supplements can affect certain sensors, so review the instructions for use.
• Size and discretion: small, low-profile sensors suit active lifestyles.

For comfort and adhesion, many users add CGM adhesive overpatches, which cover the sensor to keep it from peeling. Skin-prep wipes can also improve adhesion; ask your clinician if you have a history of skin irritation.

Cost and coverage

CGM costs include the sensors, a reader or compatible phone, and possibly a transmitter. Insurance coverage varies widely, so check with your plan, your pharmacy, and the manufacturer about eligibility. Compare the cost per day of wear rather than per sensor, because wear times differ. If you buy through a pharmacy or supplier, confirm return policies and shipment timing so you do not run out. Avoid unauthorized resellers, and verify expiration dates on sensors.

Supplies worth keeping on hand

Even with a CGM, a backup blood glucose meter and test strips is recommended in most instructions for use, for situations when symptoms do not match readings or when the sensor fails. Keep fast-acting glucose supplies and a written plan from your provider, and learn how the device handles signal loss.

Privacy and data

CGM apps store sensitive health data. Review what the app shares, set a device passcode, and be careful about who can follow your readings. Updates and compatibility change often, so keep the app current and check support lists before upgrading your phone. Also think about travel: carry extra sensors, check airport screening guidance from the manufacturer, and keep documentation from your provider in case you need to explain your device.

Questions to ask before you buy

• Does my insurance cover this specific brand, and what is the out-of-pocket cost per month?
• Which phones and operating system versions does the app support?
• How long does it take to receive replacement sensors if one fails early?
• Does the system integrate with my insulin pump or smart pen, if I use one?

Bring these to your appointment so your care team can steer you toward a device that fits both your medical needs and your daily routine. Also ask about training on the app and how to share data with your clinic before your first sensor goes on.

Plan for the learning curve as well. The first sensor often feels strange, and alerts can seem overwhelming, so many people start with conservative alarm settings and adjust them with their care team. Reading the instructions for use carefully, including warnings about exercise, sleep position, and sensor compression lows, helps you interpret odd readings. If a reading does not match how you feel, follow the guidance in your device instructions and confirm with a fingerstick.

Frequently asked questions

Do I need a prescription?

Many systems require one, though some newer options are available over the counter. Check the current status for your chosen device.

Are CGM readings the same as blood tests?

No. They measure glucose in interstitial fluid and can lag behind blood values, especially when levels change rapidly. Confirm with a fingerstick when advised.

Can I switch brands?

Often yes, but talk to your clinician first, since alerts, settings, and pump compatibility may differ.