Do you need a continuous glucose monitor?
Usually only if you have diabetes. Everyone in England with type 1 should be offered one. Without diabetes, healthy sugar spikes too, so a blood test answers ‘is my sugar a problem?’ better.
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Do I need a continuous glucose monitor?
Usually only if you have diabetes, and not always then. A continuous glucose monitor (CGM) is a small sensor under your skin that reads your sugar day and night.
NICE says adults with type 1 diabetes should be offered one. So should children with type 1 in England. With type 2, it depends on your insulin.
| You have | On the NHS? |
|---|---|
| Type 1 diabetes, at any age or in pregnancy | Yes. You should be offered one. |
| Type 2, with insulin injections several times a day | Yes, if you get hypos (low sugar) often or badly, or don’t feel them coming. Also if you can’t do finger pricks, or would need 8 or more a day. |
| Type 2, on insulin, and need a carer to check your sugar | Yes. |
| Type 2, not on insulin | NICE’s CGM advice doesn’t cover you. Ask your diabetes team. |
| No diabetes | No. You would pay for it yourself. |
Sources: NICE NG17; NICE NG28; Diabetes UK
Think you qualify? Ask your diabetes team. They can help you decide if a CGM suits you.
Never stop or change a prescribed medicine without your prescriber.
How does a glucose monitor on your arm work?
One common type, described by NICE, is a disc a few centimetres across. It usually sits on your upper arm, with a thin, bendy fibre 5 mm under your skin. Most people say putting it in is painless.
How a CGM gets a number to your phone
- 1
Sensor goes in
You press it on with an applicator.
- 2
It reads the fluid
It checks the sugar in the fluid around your cells, not your blood.
- 3
Readings reach you
Real-time CGMs send them to your phone. With flash, you scan the sensor.
- 4
Finger prick when it counts
If a reading doesn’t match how you feel, or you’re treating a hypo.
Sources: Diabetes UK; NICE
That fluid lags your blood by up to 15 minutes. The gap is more likely to be bigger when you’re eating or exercising.
So a CGM is like a news report from a few minutes ago. Mostly right, but less so when things change fast. When you need to act on a low, a finger prick shows you now.
Keep your meter. More on that in checking sugar without finger pricks.
Is continuous glucose monitoring worth it without diabetes?
For most people, probably not. NICE’s CGM advice is only for people with diabetes. And a healthy graph isn’t flat.
In one US study, 153 healthy people aged 7 to 80, not obese and not pregnant, wore a sensor for up to 10 days.
| Sensor reading | Typical result |
|---|---|
| Average sugar | 5.4 to 5.5 mmol/L, or 5.8 over age 60 |
| Time between 3.9 and 7.8 | 96% of the day |
| Time above 7.8 | About 30 minutes a day |
| Time below 3.9 | About 15 minutes a day |
Source: Shah et al, 2019
So short spikes showed up in healthy people too. One spike after lunch can’t tell you if your sugar is a problem.
A blood test can. A US study of 972 people found that in the 232 with normal sugar, sensor numbers barely matched it.
That blood test is HbA1c, which shows your average sugar over the last few months. If you’re asking about prediabetes (sugar higher than normal, but not diabetes), one diabetes expert wrote in 2026, HbA1c is the most practical answer.
Compare the two in CGM vs HbA1c.
Will a CGM help me lose weight?
The trials so far don’t show it.
A 2024 review pooled 25 trials with 2,996 adults. Most had diabetes. Only 3 trials were in people with obesity.
Feedback from a CGM lowered HbA1c a little, by 0.28%. It made no clear difference to weight or BMI.
Want steps with more evidence behind them? See how to lower blood sugar naturally.
How much does a continuous glucose monitor cost?
Paying yourself? Diabetes UK says CGMs cost about £50 to £150 a month, depending on the device.
There’s no single best one. The right CGM depends on your needs, and sensors for one CGM won’t work in another.
A CGM may not suit you if you don’t like wearing kit on your body, or lots of data would worry you.
Before you pay for a CGM
- Have diabetes? Ask your diabetes team if you qualify on the NHS first.
- No diabetes but worried about your sugar? Get an HbA1c blood test first.
- Budget about £50 to £150 a month.
- Buy sensors made for your exact device.
- Avoid any watch that claims to read sugar without a sensor on your body.
- Report a safety problem to the MHRA Yellow Card scheme.
Sources: Diabetes UK; DeVries, 2026
When to speak to a GP
Not everyone with diabetes has symptoms. The NHS checks for it with a blood test, not a sensor. See a GP if:
- You or your child has signs of diabetes: feeling thirsty all the time, peeing more than usual, feeling very tired or losing weight without trying. Ask for an urgent appointment or call 111.
- You have a higher chance of diabetes, even with no symptoms.
- You don’t have diabetes but get signs of low sugar, such as shaking, sweating, a fast heartbeat and feeling confused.
- You have diabetes and get hypos often, have had severe hypos or hypos at night, or don’t always notice them.
Someone with very low sugar is unconscious or not responding normally? Call 999 if there’s no glucagon (an emergency hypo injection) or you don’t know how to use it.
Also call 999 if they haven’t recovered 10 minutes after glucagon, or they’ve been drinking alcohol.
For which test checks for diabetes, see the diabetes blood test guide.