Condition guide · Diabetes
Continuous glucose monitoring (CGM): how it works and who it helps
A continuous glucose monitor (CGM) is a small wearable sensor that tracks your glucose around the clock and sends readings to a phone or receiver — without routine fingersticks. For many people with diabetes, it turns scattered snapshots into a continuous, clearer picture.
Educational overview drawn from public health sources (e.g., NIH, CDC, American Diabetes Association).Educational information, not medical advice — talk with your physician about what's right for you.
What is a CGM?
A CGM is a small sensor worn on the skin — usually the upper arm or abdomen — with a tiny filament just under the surface that measures glucose in the fluid between cells every few minutes. A transmitter sends those readings to a display so you can see your level at a glance.
How it works
Beyond a single number, a CGM shows trend arrows — whether glucose is rising, steady, or falling — and can alert you to highs and lows, including overnight. That direction-and-alert information is what fingersticks alone can't give you.
CGM vs. fingerstick meters
A fingerstick meter gives an accurate point-in-time reading; a CGM gives a continuous stream plus trends and alerts, with far fewer finger pokes. Many people find the continuous view helps them and their care team make clearer day-to-day decisions.
Who benefits
CGMs are especially useful for people who take insulin, those who experience frequent or unpredictable lows, and anyone who needs a tighter picture of their glucose patterns. Medicare covers CGMs for people who meet its criteria — details on our coverage page.
Getting started
A provider prescribes the CGM, and a diabetes educator or supplier helps with setup and the first sensor. From there, it's largely automatic — the sensor is replaced on its schedule (every 10–15 days depending on the brand).
Think a CGM is right for you? Check your Medicare coverage.
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Common questions
Does Medicare cover a CGM?+
Yes — Medicare Part B covers therapeutic CGMs and their supplies for people who meet the coverage criteria. See our coverage page for who qualifies, or check your eligibility below.
Have a question?
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