Blood Sugar Levels Chart: Normal Ranges for Fasting, After Meals and A1C (mg/dL and mmol/L)
Quick answer: For adults without diabetes, a normal fasting blood sugar is under 100 mg/dL (5.6 mmol/L), and a normal reading 2 hours after a glucose drink is under 140 mg/dL (7.8 mmol/L). A normal A1C is under 5.7%. Fasting 100 to 125 mg/dL or A1C 5.7% to 6.4% is the prediabetes range. Fasting 126 mg/dL (7.0 mmol/L) or above, or A1C 6.5% or above, points to diabetes, but a doctor must confirm it with a lab test.
Blood sugar (blood glucose) numbers come up at check-ups, on home meters, on smartwatches and on lab reports, and they are written in two different units depending on where you live. This guide puts the main ranges in one place: what is normal, what counts as prediabetes and diabetes, and the day-to-day targets usually suggested for people who already have diabetes.
It is also timely. World Diabetes Day is on 14 November, and the theme for 2026 and 2027 is Early action on diabetes. The International Diabetes Federation estimates that almost 1 in 2 adults living with diabetes has not been diagnosed, often because type 2 diabetes can develop slowly with few clear symptoms. Knowing what your numbers mean is a simple first step.
Blood sugar levels chart for adults
These are the diagnostic ranges used by the American Diabetes Association (ADA) in its 2026 Standards of Care. They are based on lab tests of blood plasma, not on a single finger-prick reading.
| Test | Normal | Prediabetes | Diabetes |
|---|---|---|---|
| Fasting plasma glucose (no food for at least 8 hours) | Under 100 mg/dL (under 5.6 mmol/L) |
100 to 125 mg/dL (5.6 to 6.9 mmol/L) |
126 mg/dL or higher (7.0 mmol/L or higher) |
| 2 hours into an oral glucose tolerance test (75 g glucose drink) | Under 140 mg/dL (under 7.8 mmol/L) |
140 to 199 mg/dL (7.8 to 11.0 mmol/L) |
200 mg/dL or higher (11.1 mmol/L or higher) |
| A1C (HbA1c), your average over about 2 to 3 months | Under 5.7% (under 39 mmol/mol) |
5.7% to 6.4% (39 to 47 mmol/mol) |
6.5% or higher (48 mmol/mol or higher) |
| Random glucose (any time of day) | Not used on its own | 200 mg/dL or higher (11.1 mmol/L) with classic symptoms | |
A note on UK and WHO numbers: the World Health Organization and NICE in the UK set the lower end of the impaired fasting glucose range a little higher, at 110 mg/dL (6.1 mmol/L), and NICE uses an HbA1c of 42 to 47 mmol/mol (6.0% to 6.4%) to flag a high risk of type 2 diabetes. The diabetes cut-offs are the same everywhere.
What is a normal blood sugar level during the day?
Blood sugar is not fixed. In most people without diabetes it is lowest first thing in the morning and before meals, rises after eating, and usually comes back down within 2 to 3 hours. As a rough guide:
- On waking or before meals: about 70 to 99 mg/dL (3.9 to 5.5 mmol/L).
- 1 to 2 hours after eating: usually under 140 mg/dL (7.8 mmol/L).
A single higher reading after a large, carbohydrate-heavy meal is not a diagnosis. What matters is the pattern, and a lab test if your doctor is concerned.
Target ranges if you have diabetes
If you already have diabetes, your care team will give you personal targets. These are the general starting points used by major guidelines for most non-pregnant adults:
| Reading | ADA (US) | NHS / NICE (UK) |
|---|---|---|
| Before meals | 80 to 130 mg/dL (4.4 to 7.2 mmol/L) | 4 to 7 mmol/L (72 to 126 mg/dL) |
| After meals | Under 180 mg/dL (10.0 mmol/L) at 1 to 2 hours | Type 2: under 8.5 mmol/L (153 mg/dL) at 2 hours Type 1: 5 to 9 mmol/L (90 to 162 mg/dL) at least 90 minutes after eating |
| A1C / HbA1c | Under 7% for many adults | Usually 48 mmol/mol (6.5%), or 53 mmol/mol (7.0%) on medicines that can cause hypos |
| Continuous glucose monitor (CGM) | More than 70% of the day spent between 70 and 180 mg/dL (3.9 to 10.0 mmol/L) is a common goal | |
Targets are often relaxed for older adults, people with other health conditions, and anyone who has frequent low blood sugar. Targets in pregnancy are much tighter. Always follow the numbers your own doctor or diabetes nurse sets for you.
Low blood sugar (hypoglycaemia)
Low blood sugar mainly affects people who take insulin or certain tablets such as sulphonylureas. The usual thresholds are:
- Below 70 mg/dL (3.9 mmol/L): low. The NHS uses under 4 mmol/L, which is why you may hear “four is the floor”.
- Below 54 mg/dL (3.0 mmol/L): clinically significant low blood sugar that needs prompt treatment.
Common signs include shaking, sweating, feeling hungry, a fast heartbeat, tingling lips, irritability and confusion.
Get help straight away if someone with diabetes is very drowsy, confused, having a seizure or cannot swallow safely, or if very high blood sugar comes with vomiting, deep fast breathing, stomach pain or fruity-smelling breath. Call your local emergency number (999 in the UK, 911 in the US, 1122 in Pakistan).
How to convert mg/dL and mmol/L
The US mostly uses mg/dL; the UK, Europe, Canada and Australia mostly use mmol/L. Many meters let you choose. To convert:
- mg/dL to mmol/L: divide by 18. Example: 126 ÷ 18 = 7.0 mmol/L.
- mmol/L to mg/dL: multiply by 18. Example: 5.5 × 18 = 99 mg/dL.
| mg/dL | mmol/L | What it usually means |
|---|---|---|
| 54 | 3.0 | Clinically significant low |
| 70 | 3.9 | Low threshold |
| 100 | 5.6 | Top of normal fasting (ADA) |
| 126 | 7.0 | Fasting diabetes threshold |
| 140 | 7.8 | Top of normal 2-hour glucose test |
| 180 | 10.0 | Common upper target after meals with diabetes |
| 200 | 11.1 | 2-hour or random diabetes threshold |
Signs your blood sugar may be high
Many people with raised blood sugar notice nothing at all, which is why testing matters. When symptoms do appear, they can include:
- Feeling very thirsty
- Peeing more than usual, especially at night
- Feeling very tired
- Losing weight without trying
- Itching around the genitals or repeated thrush
- Cuts or wounds that heal slowly
- Blurred vision
If you have any of these, see a doctor and ask for a blood test. Type 1 diabetes in particular can come on quickly, over days or weeks, and needs urgent care.
How to check your blood sugar at home
If your doctor has asked you to monitor your blood sugar, a few habits make readings more reliable:
- Wash and dry your hands before a finger-prick test. Sugar on your skin, for example from fruit, can give a falsely high result.
- Use the side of a fingertip and rotate fingers to reduce soreness.
- Check strips are in date and stored as the pack says; heat and damp affect accuracy.
- Write down the time and context: fasting, before a meal, or how long after eating. A number without context is hard to interpret.
- Bring your log to appointments. Patterns over a week or two are more useful to your doctor than any single reading.
Home meters and CGMs are for monitoring. They are not used on their own to diagnose diabetes; that needs a lab test, usually repeated to confirm.
Who should get tested?
In the US, the Preventive Services Task Force recommends screening adults aged 35 to 70 who have overweight or obesity, and the ADA suggests testing all adults from age 35. You may need testing earlier if you have risk factors such as a close family member with type 2 diabetes, a history of diabetes in pregnancy, high blood pressure, or South Asian, Black African or African Caribbean heritage, which carry a higher risk at a lower body weight. In the UK, the free NHS Health Check for adults aged 40 to 74 includes a diabetes risk assessment.
Everyday habits that support healthy blood sugar
For people with prediabetes, lifestyle changes can lower the chance of developing type 2 diabetes. These habits help most people:
- Move more, including after meals. Even a 10 to 15 minute walk after eating can blunt the rise. See how many steps a day you really need.
- Eat more fibre from vegetables, beans, lentils, oats and whole grains. Our guide to how much fibre you need per day shows how to add it gradually.
- Cut back on sugary drinks and added sugar. Start with the limits in how much sugar per day.
- Aim for a healthy weight. Losing even 5% to 7% of body weight lowers risk for many people with prediabetes.
- Sleep well and manage stress. Short sleep and ongoing stress can both nudge blood sugar up.
- Keep your other numbers in view. Diabetes often travels with high blood pressure and cholesterol, so check those too.
Weight is one of the biggest risk factors for type 2 diabetes. Check where you stand in a few seconds.
Frequently asked questions
What is a normal blood sugar level for adults?
A normal fasting blood sugar is under 100 mg/dL (5.6 mmol/L). Two hours after eating, it is usually under 140 mg/dL (7.8 mmol/L). A normal A1C is under 5.7%.
Is a fasting blood sugar of 110 mg/dL bad?
110 mg/dL (6.1 mmol/L) is in the prediabetes range under ADA criteria. It does not mean you have diabetes, but it is worth repeating the test and talking to your doctor about reducing your risk.
What blood sugar level is dangerous?
Below 54 mg/dL (3.0 mmol/L) is a dangerous low that needs treating straight away. Very high readings, especially above 250 to 300 mg/dL (about 14 to 17 mmol/L) with feeling unwell, vomiting or drowsiness, need urgent medical advice.
What is the difference between blood sugar and A1C?
A blood sugar reading is a snapshot of that moment. A1C reflects your average blood sugar over roughly the past 2 to 3 months, so it is not affected by what you ate this morning.
Can a home glucose meter diagnose diabetes?
No. Home meters and continuous glucose monitors are for monitoring. Diabetes is diagnosed with lab tests, usually fasting glucose, an oral glucose tolerance test or A1C, and normally confirmed with a second test.