Normal blood sugar levels in the UK (mmol/L)

Reviewed by the JForH team · 2026-10-30

The NHS says a blood sugar over 7 mmol/L before eating, or over 11 mmol/L at least 90 minutes after eating, is high, and below 4 mmol/L is low. NICE sets no finger-prick targets for type 2 diabetes and doesn't routinely advise home testing unless you take insulin or a medicine that can cause hypos. Your HbA1c, with a target of 48 or 53 mmol/mol, is the main measure.

What are normal blood sugar levels in the UK (mmol/L)?

The NHS doesn't publish a single 'normal' range for home tests. It gives the levels that count as high and low, and the space between is where most people sit most of the day.

The NHS says its high levels are a guide. Your own targets may be different, and your GP or diabetes nurse sets them with you.

Blood sugar rises after every meal, even without diabetes, and falls back within a few hours. One reading on its own tells you little. The pattern over weeks matters more.

What are the NHS blood sugar targets for type 2 diabetes?

For finger-prick tests, there aren't any national ones. Diabetes UK puts it plainly: 'there are currently no NICE recommendations' for these targets in type 2 diabetes.

What NICE does set is an HbA1c target, from a blood test every few months:

• 48 mmol/mol (6.5%) if you manage with diet and activity, or take a medicine that doesn't cause hypos.
• 53 mmol/mol (7.0%) if you take a medicine that can cause hypos, such as gliclazide or insulin.

If you do test at home, agree your own numbers with your GP or diabetes nurse and write them down.

Where do '4–7 before meals' and 'under 8.5 after meals' come from?

You'll see these figures on many charts. They come from older NICE advice and forum material, not the current NICE guideline for type 2 diabetes (NG28, last updated February 2026). They aren't wrong as a rough guide, but they aren't an official NHS target for type 2. Use the numbers your own team gives you.

Should I test my own blood sugar with type 2 diabetes?

Usually not, unless your medicines or job make it necessary. NICE NG28 says not to routinely offer home testing to adults with type 2 diabetes unless they:

• take insulin,
• have had hypos,
• take a medicine that can cause hypos and drive or use machinery, or
• are pregnant or planning a pregnancy.

This surprises people who've read American advice to check after every meal. In the UK, if you manage with diet, metformin or other medicines that don't cause hypos, HbA1c every 3 to 6 months does most of the work. Some people choose to test anyway to learn how food affects them. That's fine, but you may have to buy your own strips.

What should my blood sugar be after eating?

The NHS counts a home reading over 11 mmol/L, taken at least 90 minutes after eating, as high. Below that is within its guide.

There's no UK target for after meals in type 2 diabetes. Adults with type 1 are given 5–9 mmol/L at least 90 minutes after eating by Diabetes UK, and some people with type 2 borrow that as a rough aim. Ask before you do.

Here is an example. Porridge with a banana might take you to 9 mmol/L an hour later and back to 6 by lunch. That's a normal rise. Being at 13 two hours after a takeaway curry with naan and pilau rice is worth noting and talking through.

What fasting blood sugar is normal?

The NHS counts over 7 mmol/L on waking or before eating as high. On a fasting blood test at the surgery, NHS areas use 5.5–6.9 mmol/L to refer people for prediabetes support. So below 5.5 is the range people usually mean by normal.

A fasting reading is one taken before you've eaten, usually first thing in the morning. For a fasting blood test, your surgery will tell you how long to go without food.

Can I tell if I have diabetes from a home meter?

No. A home reading over 7 can be a reason to see your GP, but diagnosis needs a lab test, usually an HbA1c. The NHS uses 48 mmol/mol (6.5%) or over as the diabetes range, and Diabetes UK puts prediabetes at 42–47 mmol/mol.

If you have symptoms such as being very thirsty, peeing a lot, feeling tired or losing weight without trying, see your GP.

What blood sugar is too low?

Below 4 mmol/L is a hypo, according to the NHS. It mostly happens to people who take insulin or medicines such as gliclazide and glimepiride.

If you are below 4 mmol/L, the NHS says:

1. Have something sugary straight away: a small glass of fruit juice or sugary fizzy drink, 5 glucose or dextrose tablets, 4 large jelly babies or 2 tubes of glucose gel.
2. Check again after 10 to 15 minutes.
3. If you're still below 4, have another sugary drink or snack and check again after 10 minutes.
4. Once you're back above 4 and feel better, eat something more filling, like a sandwich, biscuits or your next meal.

Tell your GP or diabetes nurse about any hypo. Your medicine dose may need changing.

What blood sugar is dangerously high?

The NHS doesn't give one number. It says to get help based on how you feel and on ketones.

Call 999 or go to A&E if you think your sugar is high and you are being sick, have stomach pain, fruity-smelling breath (like pear drops), are drowsy or confused, are breathing faster, or have high ketones. Don't drive yourself.

Contact your GP or care team if your sugar stays high after you've tried to bring it down.

What should blood sugar be in pregnancy?

Tighter than at other times. Diabetes UK gives these targets for any type of diabetes in pregnancy:

• Fasting: below 5.3 mmol/L
• 1 hour after meals: below 7.8 mmol/L
• 2 hours after meals: below 6.4 mmol/L

Aim to stay above 4 mmol/L. NICE says pregnant women with type 2 diabetes should be offered home testing.

What is a good time in range on a sensor?

More than 70% of the day between 3.9 and 10.0 mmol/L, for most adults with diabetes. That comes from a 2019 international consensus on sensor data.

The same consensus suggests less than 4% of the time below 3.9 mmol/L, and less than 1% below 3.0. Older or frail people are given a looser goal of more than 50% in range, to keep lows down.

How do I convert blood sugar mmol/L to mg/dL?

Multiply mmol/L by 18. So 7 mmol/L is 126 mg/dL, and 11 mmol/L is about 198 mg/dL. To go back, divide mg/dL by 18.

You'll need this when reading American websites or using a meter bought abroad. UK meters and sensors show mmol/L.

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Last updated: 2026-10-30. Educational information, not medical advice. Talk to your doctor before changing your treatment.