Without diabetes, fasting blood sugar is usually 3.9 to 5.5 mmol/L (70 to 99 mg/dL) and rises no higher than 7.8 mmol/L (140 mg/dL) after meals. Here is how normal, prediabetes and diabetes numbers compare, the targets guidelines set before and after meals and at bedtime, and why your care team may set yours differently.
Blood sugar, or blood glucose, is the amount of glucose, the sugar your body uses for fuel, in your blood. Without diabetes it stays in a fairly narrow band: a fasting reading usually sits between 3.9 and 5.5 mmol/L (70 and 99 mg/dL) 1, and after a meal glucose generally rises no higher than 7.8 mmol/L (140 mg/dL) 2.
With diabetes, the question becomes “is this on target?” Insulin and some other glucose-lowering medicines can push glucose too low 5, so targets for people with diabetes are wider than the normal range, and they change for children, pregnancy and older age 8, 9, 12.
This article covers normal ranges, diagnosis, guideline targets and A1c, with glucose in mmol/L and mg/dL in brackets. To switch between units, see our guide to mmol/L and mg/dL.
Fasting means no food or drink with calories for at least eight hours 4. Cleveland Clinic describes a healthy blood glucose level for someone without diabetes as 3.9 to 5.5 mmol/L (70 to 99 mg/dL), and adds that readings of 2.8 to 3.9 mmol/L (50 to 70 mg/dL) can also be normal 1.
In people with normal glucose tolerance, the International Diabetes Federation (IDF) says plasma glucose “generally rises no higher than 7.8 mmol/l (140 mg/dl)” after meals and typically returns to premeal levels within two to three hours 2.
A continuous glucose monitor (CGM) is a small sensor worn on the skin that records glucose every few minutes. In a 2019 multicentre study, 153 healthy people aged 7 to 80 without diabetes wore one 13. Their average glucose was 99 mg/dL (5.5 mmol/L). They spent a median of 96% of the day between 3.9 and 7.8 mmol/L (70 and 140 mg/dL), 2.1% above that range (about 30 minutes a day) and 1.1% below it (about 15 minutes a day) 13.
Age made a small difference: participants aged 60 and older averaged 5.8 mmol/L (104 mg/dL), against 5.4 to 5.5 mmol/L (98 to 99 mg/dL) in younger groups 13.
Diabetes is diagnosed with one of four blood tests, and prediabetes with the first three 4:
| Test | Normal | Prediabetes | Diabetes |
|---|---|---|---|
| Fasting glucose | Below 5.6 mmol/L (100 mg/dL) 3, 14 | 5.6–6.9 mmol/L (100–125 mg/dL); Diabetes Canada: 6.1–6.9 mmol/L 4, 14 | 7.0 mmol/L (126 mg/dL) or higher 4, 14 |
| 2 hours after a 75 g glucose drink | Below 7.8 mmol/L (140 mg/dL) 14 | 7.8–11.0 mmol/L (140–199 mg/dL) 4, 14 | 11.1 mmol/L (200 mg/dL) or higher 3, 4 |
| A1c | Below 5.7% (39 mmol/mol) 3 | 5.7–6.4% (39–46 mmol/mol); Diabetes Canada: 6.0–6.4% 4, 15 | 6.5% (48 mmol/mol) or higher 4, 15 |
| Random glucose, with symptoms | Not used | Not used | 11.1 mmol/L (200 mg/dL) or higher 4, 14 |
US criteria start prediabetes at a fasting glucose of 5.6 mmol/L (100 mg/dL) and an A1c of 5.7% 3, 14. Diabetes Canada starts it at 6.1 mmol/L (about 110 mg/dL) and 6.0% (42 mmol/mol), because people in the 6.1 to 6.9 mmol/L range have a higher risk of developing diabetes than the wider 5.6 to 6.9 mmol/L group 4. A fasting result of 5.8 mmol/L (104 mg/dL) is therefore prediabetes in the US but below the Canadian cut-off.
One high result is usually not enough. Without symptoms, Diabetes Canada requires a repeat lab test on another day; with symptoms of high blood sugar, one result in the diabetes range is enough 4. Without lifestyle changes, many people with prediabetes go on to develop type 2 diabetes, and Johns Hopkins Medicine notes that lifestyle changes can reduce that risk by about 50% 15.
Guidelines check after-meal glucose at different times. The ADA’s 2026 Standards of Care measure the after-meal value at its peak, one to two hours after the start of the meal; Diabetes Canada measures it at two hours 5, 6.
| Who and which guideline | Before meals | After meals |
|---|---|---|
| People without diabetes (typical) | 3.9–5.5 mmol/L (70–99 mg/dL), fasting 1 | Generally no higher than 7.8 mmol/L (140 mg/dL) 2 |
| ADA, many nonpregnant adults with diabetes | 4.4–7.2 mmol/L (80–130 mg/dL) 5 | Peak below 10.0 mmol/L (180 mg/dL) 5 |
| Diabetes Canada, most adults with diabetes | 4.0–7.0 mmol/L (72–126 mg/dL) 6 | 5.0–10.0 mmol/L (90–180 mg/dL) at 2 hours 6 |
If the A1c target isn’t met, Diabetes Canada says 4.0 to 5.5 mmol/L (72 to 99 mg/dL) fasting and 5.0 to 8.0 mmol/L (90 to 144 mg/dL) after meals may be considered, balanced against the risk of lows 6. The IDF’s 2011 guideline sets an after-meal target of 9.0 mmol/L (160 mg/dL), as long as lows are avoided 2. Why the rise after a meal varies so much is covered in same meal, different spike.
In plain terms: “Normal” describes a body without diabetes. A “target” is the range you and your care team aim for with diabetes. It is usually wider than normal, because pushing glucose all the way into the normal range with medicine can bring more lows.
The general ADA and Diabetes Canada targets cover before and after meals, not bedtime 5, 6. The ADA does give bedtime ranges for older adults, from 4.4 to 10.0 mmol/L (80 to 180 mg/dL) in good health to 6.1 to 11.1 mmol/L (110 to 200 mg/dL) in very complex or poor health, and says their goals should prioritize avoiding lows 9.
With a CGM, overnight readings count toward time in range, the share of readings between 3.9 and 10.0 mmol/L (70 and 180 mg/dL); the ADA’s goal for many nonpregnant adults is more than 70% 5. See time in range for more, and the dawn phenomenon if waking readings run higher than bedtime ones.
A1c sums up the past two to three months in one number 14. The ADA suggests below 7% (53 mmol/mol) for many nonpregnant adults without severe lows, a lower goal such as below 6.5% (48 mmol/mol) for some people in good health with a low risk of lows, and up to 8% (64 mmol/mol) for people with complex health 5. Diabetes Canada suggests 7.0% or lower for most people with type 1 or type 2 diabetes, and 6.5% or lower for some people with type 2 diabetes at low risk of lows 6. It allows 7.1% to 8.5% for people with recurrent severe lows, limited life expectancy, or frailty or dementia in older age 6.
The A1c-Derived Average Glucose (ADAG) study collected about 2,700 glucose readings per person over three months from 507 people, 80 of them without diabetes 7. It found average glucose (mg/dL) = 28.7 × A1c − 46.7. By that formula, an A1c of 6% matches an average of about 7.0 mmol/L (126 mg/dL), 7% about 8.6 mmol/L (154 mg/dL) and 8% about 10.2 mmol/L (183 mg/dL) 7.
An A1c of 7% sits above the before-meal targets because the average includes every after-meal rise. The ADA notes that after-meal glucose may need special attention when the A1c goal isn’t met despite before-meal readings on target 5. Our article on A1c, GMI and average glucose explains why A1c and a CGM average can disagree.
The ADA’s 2026 Standards say A1c goals for young people must be individualized and reassessed over time, and that below 7% (53 mmol/mol) is appropriate for most children and adolescents with diabetes 12. A lower goal, such as below 6.5% (48 mmol/mol), may be suggested if it can be reached without significant lows, excess weight gain or harm to well-being 12.
Diabetes Canada’s 2025 type 1 guideline set a target below 7.0% for children of all ages 16. Earlier guidelines set a higher target for children because lower targets were thought to raise the risk of severe lows; the 2025 guideline says that risk is falling with CGM, automated insulin delivery (AID) systems and intensive treatment 16.
Targets are tightest in pregnancy. The ADA’s goals are a fasting glucose below 5.3 mmol/L (95 mg/dL), and either below 7.8 mmol/L (140 mg/dL) one hour after a meal or below 6.7 mmol/L (120 mg/dL) two hours after 8. The ideal A1c is below 6% (42 mmol/mol), relaxed to below 7% (53 mmol/mol) if needed to prevent lows 8. A1c runs slightly lower in pregnancy, with or without diabetes, because red blood cells turn over faster 8. With type 1 diabetes, the CGM range in pregnancy is 3.5 to 7.8 mmol/L (63 to 140 mg/dL), with a goal of more than 70% of readings in it 8. Our article on gestational diabetes covers how it is tested and treated.
For older adults, the ADA sets goals by overall health 9. ADL means activities of daily living, such as bathing and dressing.
| Health status | A1c | Before meals | Bedtime |
|---|---|---|---|
| Healthy: few other chronic illnesses, intact thinking and daily function | Below 7.0–7.5% (53–58 mmol/mol) | 4.4–7.2 mmol/L (80–130 mg/dL) | 4.4–10.0 mmol/L (80–180 mg/dL) |
| Complex or intermediate: several chronic illnesses, two or more ADL limitations, or mild to moderate cognitive impairment | Below 8.0% (64 mmol/mol) | 5.0–8.3 mmol/L (90–150 mg/dL) | 5.6–10.0 mmol/L (100–180 mg/dL) |
| Very complex or poor health: long-term care, end-stage illness, moderate to severe cognitive impairment, or two or more ADL limitations | Avoid relying on A1c | 5.6–10.0 mmol/L (100–180 mg/dL) | 6.1–11.1 mmol/L (110–200 mg/dL) |
In very complex or poor health, the ADA says decisions should focus on avoiding lows and high blood sugar that causes symptoms 9.
Lower glucose protects the eyes, kidneys and nerves, at a price. In the Diabetes Control and Complications Trial (DCCT), 1,441 people with type 1 diabetes were followed for an average of 6.5 years 10. Intensive treatment, with a mean A1c of about 7% against about 9% 5, cut the risk of developing eye damage (retinopathy) by 76% and slowed its progression by 54% 10. It also lowered the risk of early kidney damage (microalbuminuria) by 39% and nerve damage (clinical neuropathy) by 60%. Severe lows were two to three times as common 10.
The UK Prospective Diabetes Study (UKPDS 33) followed 3,867 people newly diagnosed with type 2 diabetes. Over 10 years, A1c was 7.0% with intensive treatment and 7.9% with conventional treatment, and the intensive group had a 25% lower risk of small-blood-vessel complications 17. Major lows affected 1.8% of people a year on insulin against 0.7% on conventional treatment 17.
Lower is not always better. The ACCORD trial compared an intensive target below 6.0% with a standard target of 7.0% to 7.9% in 10,251 adults with type 2 diabetes, mean age 62.2 11. The intensive approach was stopped after a mean of 3.5 years because more people died: 257 against 203 (hazard ratio 1.22) 5, 11. Lows needing someone else’s help were also more common 11.
So the ADA asks care teams to weigh how long someone has had diabetes, age and life expectancy, other health conditions, the risk of lows, resources and support, and the person’s preferences through shared decision-making 5. Diabetes Canada’s first recommendation on targets is that they “should be individualized” 6.
The ADA defines three levels of low blood sugar. Level 1 is below 3.9 mmol/L (70 mg/dL) and at or above 3.0 mmol/L (54 mg/dL). Level 2 is below 3.0 mmol/L (54 mg/dL). Level 3 is a severe event in which changes in mental or physical state mean the person needs someone else’s help 5. Our article on low blood sugar covers warning signs and treatment.
Early signs of high blood sugar include frequent urination, increased thirst, blurred vision and feeling weak or unusually tired. Mayo Clinic advises people with diabetes to seek immediate help from their care provider or call 911 if they have ongoing diarrhea or vomiting and can’t keep food or fluids down, or if glucose stays above 13.3 mmol/L (240 mg/dL) with symptoms of ketones in their urine 18. Without diabetes, symptoms like these are worth raising with a doctor; with symptoms, one lab result in the diabetes range is enough for a diagnosis 4.
Without diabetes, glucose generally rises no higher than 7.8 mmol/L (140 mg/dL) after a meal and returns to its premeal level within two to three hours 2. In a CGM study of healthy people, it was above 7.8 mmol/L for a median of 2.1% of the day 13. For many nonpregnant adults with diabetes, the ADA’s target is a peak below 10.0 mmol/L (180 mg/dL) 5.
Below 5.6 mmol/L (100 mg/dL) is normal by US criteria, and Cleveland Clinic gives 3.9 to 5.5 mmol/L (70 to 99 mg/dL) as healthy 1, 14. A result of 7.0 mmol/L (126 mg/dL) or higher on two separate tests means diabetes 14. In between is prediabetes, which Diabetes Canada starts at 6.1 mmol/L 4.
General adult guidelines set targets for before and after meals, not bedtime 5, 6. For older adults, the ADA’s bedtime ranges run from 4.4 to 10.0 mmol/L (80 to 180 mg/dL) in good health to 6.1 to 11.1 mmol/L (110 to 200 mg/dL) in very complex or poor health 9.
Below 5.7% (39 mmol/mol) is normal, 5.7% to 6.4% is prediabetes and 6.5% (48 mmol/mol) or higher is diabetes by US criteria 3. Diabetes Canada starts prediabetes at 6.0% 4. For many nonpregnant adults with diabetes, the ADA’s goal is below 7% (53 mmol/mol) 5.
A little. In the CGM study, healthy people aged 60 and older averaged 5.8 mmol/L (104 mg/dL), against 5.4 to 5.5 mmol/L (98 to 99 mg/dL) in younger groups 13. Targets for people with diabetes vary more, from an A1c below 7% for most children to below 8.0% for older adults with complex health 9, 12.
Ranges and targets are easier to read next to your own data. In Glyve’s day view, the glucose line shows your own target range shaded, with logged meals, insulin, exercise, sleep and stress on the same line, so you can see how high glucose went after a meal, how long it took to come down, and where it sat at bedtime. You can log by typing, voice or photo, and each estimate is a draft you check before saving. The week view shows whether fasting or bedtime readings follow a pattern. Glyve reads glucose from Apple Health, and Dexcom and FreeStyle Libre readings through those companies’ sharing services. Glyve is not a medical device and gives no advice; your target range is a question for your care team.
How we write about diabetes. Spotted a mistake? Email info@glyve.ca and we’ll check it against the source.
Glyve keeps glucose, food, insulin, exercise, sleep and stress on one timeline.
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