Normal Blood Sugar Levels Chart (mg/dL and mmol/L): Fasting, After Meals, Random and HbA1c

A normal fasting blood sugar for an adult without diabetes is 99 mg/dL (5.5 mmol/L) or below.^[1][2] A fasting result of 100 to 125 mg/dL (5.6 to 6.9 mmol/L) falls in the prediabetes range. A result of 126 mg/dL (7.0 mmol/L) or above falls in the diabetes range.^[1] This guide puts every common number in one place. You get fasting, after meals, random and HbA1c values in both units, plus the targets used for people who already have diabetes.

This guide is general education. If you use insulin or other glucose medicines, follow the plan your diabetes team gave you.

Normal blood sugar levels chart

The first table shows the cut-offs used to diagnose prediabetes and diabetes. The figures come from the CDC and NIDDK, which follow the ADA criteria.^[1][2] The mmol/L values are the mg/dL values divided by 18 and rounded to one decimal place.

Blood sugar chart for adults without a diabetes diagnosis

Sources: NIDDK and CDC.^[1][2] The CDC lists the normal glucose tolerance reading as 140 mg/dL (7.8 mmol/L) or below while NIDDK says 139 mg/dL (7.7 mmol/L) or below. Both place 140 mg/dL (7.8 mmol/L) at the start of prediabetes.^[1][2]

Targets for adults who have diabetes

Targets for people with diabetes are a different thing from diagnostic cut-offs. They are goals for day-to-day readings and they are set for each person.^[3]

Sources: ADA and NICE NG17.^[3][7] NICE writes its targets in mmol/L only. The mg/dL figures in the NICE column are conversions.

Hypoglycemia thresholds

Sources: ADA Standards of Care classification and NHS.^[6][5] Our guide to low blood sugar signs and recovery covers what to do when a reading drops.

Fasting blood sugar

A fasting test is taken after at least 8 hours without food. NIDDK says it is usually done in the morning before breakfast.^[1] It is the most searched number for a reason. It is cheap, it is simple and it gives a clean baseline.

For people without diabetes the cut-offs are clear. Normal is 99 mg/dL (5.5 mmol/L) or below. Prediabetes is 100 to 125 mg/dL (5.6 to 6.9 mmol/L). Diabetes is 126 mg/dL (7.0 mmol/L) or above.^[1][2] In the UK, Diabetes UK describes a typical fasting level in healthy people as 4.0 to 5.4 mmol/L (72 to 97 mg/dL).^[8]

A high morning reading in someone with diabetes is often linked to the dawn phenomenon. We explain it in morning glucose spikes and the dawn phenomenon.

Blood sugar after meals

Blood sugar rises after you eat. How high it goes depends on the meal, your activity and your body. There is no single official "normal after a meal" figure for people without diabetes in the US guidance. The closest standard test is the oral glucose tolerance test. You drink 75 g (about 2.6 oz) of glucose and get tested 2 hours later.^[1] A result of 139 mg/dL (7.7 mmol/L) or below is normal. 140 to 199 mg/dL (7.8 to 11.0 mmol/L) is prediabetes. 200 mg/dL (11.1 mmol/L) or above is diabetes.^[1]

Diabetes UK gives a practical figure for healthy people of up to 7.8 mmol/L (140 mg/dL) 2 hours after eating.^[8] For adults with diabetes the ADA suggests staying under 180 mg/dL (10.0 mmol/L) 1 to 2 hours after a meal starts.^[3] NICE suggests 5 to 9 mmol/L (90 to 162 mg/dL) at least 90 minutes after eating for adults with type 1 who check after meals.^[7]

Random blood sugar normal range

A random test is taken at any time of day, whatever you last ate. Because meals vary so much, the CDC and NIDDK do not give a normal or prediabetes range for it.^[1][2] They give one cut-off. A random reading of 200 mg/dL (11.1 mmol/L) or above points to diabetes, and NIDDK says this test is used when symptoms are present.^[1]

In children, NICE lists a random plasma glucose above 11 mmol/L (198 mg/dL) as a sign of type 1 diabetes alongside thirst, frequent urination, weight loss and tiredness.^[9] If you see high readings with symptoms like these, read our guide to high blood sugar symptoms and contact a doctor.

HbA1c: your 3 month average

HbA1c reflects your average glucose over roughly the past 3 months. It does not need fasting. In the US a result below 5.7% (39 mmol/mol) is normal. 5.7% to 6.4% (39 to 47 mmol/mol) is prediabetes and 6.5% (48 mmol/mol) or above is diabetes.^[1][2]

For adults with diabetes the ADA suggests below 7% (53 mmol/mol) for most nonpregnant adults.^[3] NICE in the UK uses two targets for adults with type 2. It suggests 48 mmol/mol (6.5%) for people managed by lifestyle or by a medicine not linked to hypoglycaemia. It suggests 53 mmol/mol (7.0%) for people on a medicine that can cause lows.^[10] Our full guide to the HbA1c test covers the UK high-risk band and when the result can mislead.

Normal blood sugar levels by age

Many charts online list normal blood sugar by age bracket. We could not find those brackets in the CDC, NIDDK or ADA guidance we checked. For adults without diabetes the diagnostic cut-offs above apply at every adult age.^[1]

For people with diabetes, targets are set per person. The ADA says its glucose targets are individualised and can be adjusted.^[3] NIDDK lists being 65 or older as a risk factor for low blood sugar, which is one reason older adults may agree different goals with their doctor.^[4]

Children are the one group where NICE publishes separate figures. For children and young people with type 1 diabetes it gives these ranges:^[9]

• 4 to 7 mmol/L (72 to 126 mg/dL) on waking
• 4 to 7 mmol/L (72 to 126 mg/dL) before meals
• 5 to 9 mmol/L (90 to 162 mg/dL) after meals
• At least 5 mmol/L (90 mg/dL) when driving

Pregnancy has its own targets as well. Ask your midwife or diabetes team for the numbers that apply to you.

Blood sugar units: mg/dL and mmol/L

Two units are in common use. The US reports glucose in milligrams per decilitre (mg/dL). The UK and many other countries use millimoles per litre (mmol/L). NICE writes its targets in mmol/L, and the NHS hypoglycaemia threshold of 4 mmol/L (72 mg/dL) uses the same unit.^[7][5]

The conversion is simple:

• mmol/L to mg/dL: multiply by 18. So 5.5 mmol/L is about 99 mg/dL.
• mg/dL to mmol/L: divide by 18. So 126 mg/dL is 7.0 mmol/L.

You can see the factor in the ADA tables, which pair 70 mg/dL with 3.9 mmol/L and 54 mg/dL with 3.0 mmol/L.^[6] HbA1c has its own two units. The US uses a percentage and the UK uses mmol/mol. For example 6.5% equals 48 mmol/mol.^[10]

Quick conversion chart

How to get a reliable reading at home

Home meters and sensors are useful between clinic tests. Our guide to self-monitoring your glucose covers meters, sensors and how often to check. These five habits make each number easier to trust:

1. Wash and dry your hands with soap and water before every finger-prick test so food residue does not skew the reading.^[3]
2. Record the time of the test and when you last ate or exercised so your care team can read the number in context.^[3]
3. Keep both mg/dL and mmol/L on your reference card if you read guidance from both the US and the UK.^[5][6]
4. Never diagnose diabetes or change a prescribed medicine dose from a single home meter reading.^[1][2]
5. Carry fast-acting carbohydrate if you use insulin or a sulfonylurea such as gliclazide or glimepiride.^[4][5]

A home reading cannot diagnose diabetes. Diagnosis uses lab tests, and without clear symptoms it needs two abnormal results.^[1]

When to see a doctor

Book an appointment if any of these apply:

• A fasting reading of 100 mg/dL (5.6 mmol/L) or more on a lab test.^[1]
• An HbA1c of 5.7% (39 mmol/mol) or more.^[1]
• A random reading of 200 mg/dL (11.1 mmol/L) or more, or symptoms such as strong thirst and frequent urination.^[1]
• Repeated readings below 4 mmol/L (72 mg/dL) in the UK or below 70 mg/dL (3.9 mmol/L) in the US if you have diabetes.^[4][5]

Low blood sugar usually means below 4 mmol/L (72 mg/dL) in the UK or below 70 mg/dL (3.9 mmol/L) in the US.^[5][4] Our guide to low blood sugar covers the warning signs. In the UK, the NHS says to call 999 if someone may have very low blood sugar and is not responding normally or is unconscious, and a glucagon injection is not available or you do not know how to use it, or they have not recovered within 10 minutes of a glucagon injection, or they have been drinking alcohol.^[5] In the US, the NIDDK says to call 911 right away after giving glucagon, or if no glucagon kit is available.^[4]

Questions to ask your diabetes team

• What fasting and after-meal blood glucose targets fit my age, health and medicines?^[3][7]
• What is my personal HbA1c target, and how often should we check it?^[3][10]
• Do any of my diabetes medicines put me at risk of low blood sugar below 4 mmol/L (72 mg/dL) or 70 mg/dL (3.9 mmol/L)?^[4][5]
• How often should I check my blood glucose at home, and which readings should prompt a call?^[3][7]

Frequently asked questions

What is a normal blood sugar level for adults?

A normal fasting level is 99 mg/dL (5.5 mmol/L) or below, and a normal HbA1c is below 5.7% (39 mmol/mol).^[1] Levels after food are higher and vary from meal to meal.

Is a fasting blood sugar of 100 normal?

No. 100 mg/dL (5.6 mmol/L) is the first value in the prediabetes range, which runs to 125 mg/dL (6.9 mmol/L).^[1] A single result is not a diagnosis, so ask your doctor about a repeat test.

What is a normal random blood sugar?

There is no official normal range for a random test. The CDC and NIDDK only set a diabetes cut-off of 200 mg/dL (11.1 mmol/L) or above.^[1][2]

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

Multiply by 18. For example 7.0 mmol/L is 126 mg/dL. To go from mg/dL to mmol/L, divide by 18.^[6]

What blood sugar level is too low?

The ADA treats below 70 mg/dL (3.9 mmol/L) as a low that needs action and below 54 mg/dL (3.0 mmol/L) as clinically significant.^[6] The NHS uses below 4 mmol/L (72 mg/dL).^[5]

What blood sugar levels should a person with diabetes aim for?

For most nonpregnant adults the ADA suggests 80 to 130 mg/dL (4.4 to 7.2 mmol/L) before meals, under 180 mg/dL (10.0 mmol/L) after meals and an HbA1c below 7% (53 mmol/mol).^[3] Your own targets may differ, so agree them with your care team.

Where to go next

For more on what your numbers mean and how to track them safely, see:

• The HbA1c test, for how the 3-month average works and when it can mislead.
• Low blood sugar signs and recovery, for what to do when a reading drops.
• Is Diabec legit?, for what is in our supplement and what it does not do.

Note: If you are pregnant, breastfeeding, or considering giving any supplement or herbal product to a child, consult your healthcare provider before making any changes to your diet, supplement routine, or prescribed medications.