For adults without diabetes, a normal fasting blood sugar is 99 mg/dL or below, a normal two-hour glucose test is 139 mg/dL or below, and a normal A1C is under 5.7%. The same cutoffs apply at every adult age. Healthy people average about 98 to 99 mg/dL across the day. Pregnancy and diabetes use separate goals set with a care team.
On this page
- What are normal blood sugar levels?
- What is a normal fasting blood sugar?
- What is the A1C normal range?
- What should blood sugar be after eating?
- Is there a normal blood sugar levels chart by age?
- What are normal blood sugar targets in pregnancy?
- When should you worry about your blood sugar?
- Can low blood sugar happen without diabetes?
- How do you check your blood sugar at home?
- Do supplements bring blood sugar back to normal?
- What doctors use first
- Practical checklist
- Bottom line
- FAQ
Normal blood sugar levels for an adult without diabetes are a fasting reading of 99 mg/dL or below and an A1C below 5.7%. To build these charts we read the NIDDK diagnosis page, two MedlinePlus lab test guides, four chapters of the American Diabetes Association 2026 Standards of Care and three studies of healthy people, using the steps on our how we review page.[1][3][4]
The short answer: fasting under 100 mg/dL, under 140 mg/dL two hours after a sugar drink, and an A1C under 5.7% all count as normal, and the same cutoffs apply at every adult age.[1]
| Fasting (8 hours or more without food) | 99 mg/dL or below is normal. 100 to 125 is prediabetes. 126 or higher points to diabetes.[1] |
|---|---|
| 2 hours after a glucose drink | 139 mg/dL or below is normal. 140 to 199 is prediabetes. 200 or higher points to diabetes.[1] |
| A1C (2 to 3 month average) | Below 5.7% is normal. 5.7% to 6.4% is prediabetes. 6.5% or higher points to diabetes.[1][3] |
| Typical day in healthy people | An average of 98 to 99 mg/dL on a sensor, with about 96% of the day spent between 70 and 140.[5] |
| Low | Under 70 mg/dL is low for many people with diabetes. Under 54 mg/dL needs action right away.[4][11] |
| Who sets different goals | People with diabetes, older adults with health problems, children with type 1 and pregnant people each have their own targets.[4][7][8][9] |
What are normal blood sugar levels?
Blood sugar, or blood glucose, is the main sugar in your blood and the body’s main source of energy. For adults without diabetes, the NIDDK lists a normal fasting level as 99 mg/dL or below, a normal two-hour glucose test result as 139 mg/dL or below, and a normal A1C as below 5.7%.[1]
Each number comes from a different test. Doctors use them to find diabetes and prediabetes, so they are cutoffs, and readings move around them through the day.[1][2]
| Test | Normal | Prediabetes | Diabetes |
|---|---|---|---|
| A1C | Below 5.7% | 5.7% to 6.4% | 6.5% or higher |
| Fasting plasma glucose | 99 mg/dL or below | 100 to 125 mg/dL | 126 mg/dL or higher |
| Oral glucose tolerance test (2 hours) | 139 mg/dL or below | 140 to 199 mg/dL | 200 mg/dL or higher |
A random test of 200 mg/dL or higher, together with classic symptoms such as thirst and frequent urination, also points to diabetes. A doctor will usually confirm a high result with a second test on another day.[1]
What is a normal fasting blood sugar?
A normal fasting blood sugar is 99 mg/dL or below after at least 8 hours with no food or drink other than water. A result of 100 to 125 mg/dL means prediabetes, and 126 mg/dL or higher on two tests means diabetes.[1]
Fasting is the most common way to check because it removes the effect of your last meal. A meter at home gives a quick number, but only a lab test is used for diagnosis.[1][2]
A high fasting number is not always diabetes. MedlinePlus lists other causes, including an overactive thyroid, pancreas problems, adrenal gland problems, some medicines, and stress from surgery, very serious illness or injury. That is one reason a single reading is rarely the final word.[2]
If your fasting number lands in the 100 to 125 range, our guide to prediabetes A1C range, symptoms and how to lower your numbers explains what that result means and what to do next.
What is the A1C normal range?
The A1C test shows your average blood sugar over the past two to three months, and the normal range is below 5.7%. A result of 5.7% to 6.4% means prediabetes, and 6.5% or higher means diabetes.[1][3]
You do not need to fast for an A1C, which makes it easy to add to routine blood work. MedlinePlus notes that what is normal for you can depend on your health, age and other factors. Some types of anemia can make the result less accurate, and the test is not used to diagnose gestational diabetes.[3]
You can also turn an A1C into the kind of number a meter shows. A 2008 study of 507 people (268 with type 1 diabetes, 159 with type 2 and 80 without diabetes) collected about 2,700 glucose readings from each person over 3 months. It produced a formula for estimated average glucose: 28.7 x A1C minus 46.7.[10]
| A1C | Estimated average glucose | What the A1C means |
|---|---|---|
| 5% | 97 mg/dL | Normal |
| 5.7% | 117 mg/dL | Start of prediabetes range |
| 6% | 126 mg/dL | Prediabetes |
| 6.5% | 140 mg/dL | Diabetes cutoff |
| 7% | 154 mg/dL | Common goal for adults with diabetes |
| 8% | 183 mg/dL | Goal for some older adults with complex health |
We worked out each average glucose value from the published formula, rounded to the nearest whole number. The formula fit the readings well, with an R2 of 0.84.[10]
What should blood sugar be after eating?
In healthy people, blood sugar rises after a meal and usually stays under 140 mg/dL, coming back down within a few hours. The lab version of this check is the two-hour glucose tolerance test, where 139 mg/dL or below is normal.[1][5]
We could not find a guideline that sets an official “normal” one-hour after-meal number for people without diabetes. The best real-world data comes from a 2019 study that fitted 153 healthy volunteers, aged 7 to 80, with a Dexcom G6 sensor for up to 10 days.[5]
Those volunteers spent a median of 96% of the day between 70 and 140 mg/dL. Time above 140 was about 2.1% of the day, or roughly 30 minutes, and time below 70 was about 1.1%, or 15 minutes.[5]
For adults who have diabetes, the ADA goal is a peak after-meal reading under 180 mg/dL and a before-meal reading of 80 to 130 mg/dL. Those are treatment goals, set to balance safety against lows, and they sit above what healthy people see.[4]
Is there a normal blood sugar levels chart by age?
No official chart sets different normal cutoffs by age: the adult diagnostic numbers are the same at 25 and at 75. Studies of healthy people do show small shifts with age, and goals for people with diabetes change with age and health.[1][5][6]
| Age group | Average glucose |
|---|---|
| 6 to under 12 | 99 mg/dL |
| 12 to under 18 | 98 mg/dL |
| 18 to under 25 | 98 mg/dL |
| 25 to under 60 | 99 mg/dL |
| 60 and older | 104 mg/dL |
The group aged 60 and older also spent a little less time in the 70 to 140 range, at 93% compared with 96% overall.[5]
A1C creeps up with age too. In 2,473 Framingham adults and 3,270 NHANES adults without diabetes, A1C rose by about 0.014 and 0.010 points per year. The upper end of normal (the 97.5th percentile) was 6.0% and 5.6% under age 40, compared with 6.6% and 6.2% at 70 and older. The authors said more research is needed before anyone uses age-specific cutoffs.[6]
| Group | A1C goal | Fasting or before meals | Bedtime |
|---|---|---|---|
| Most adults | Under 7.0% | 80 to 130 mg/dL | Not set |
| Healthy older adults | Under 7.0% to 7.5% | 80 to 130 mg/dL | 80 to 180 mg/dL |
| Older adults with complex or intermediate health | Under 8.0% | 90 to 150 mg/dL | 100 to 180 mg/dL |
| Children and teens with type 1 | Under 7% for most (under 6.5% if safe) | Set with the care team | Set with the care team |
Sources for the table: adult goals from the ADA glycemic goals chapter, older adult goals from the ADA older adults chapter, and child goals from the ADA children and adolescents chapter.[4][7][8]
What are normal blood sugar targets in pregnancy?
Pregnancy uses tighter numbers: the ADA goals are a fasting level under 95 mg/dL and either under 140 mg/dL one hour after eating or under 120 mg/dL two hours after. These goals are for people with diabetes during pregnancy, including gestational diabetes.[9]
A1C runs slightly lower during pregnancy. The ADA suggests an A1C under 6% as the ideal if it can be reached without significant lows.[9]
The NIDDK notes that gestational diabetes is checked with different tests and cutoffs from the standard adult ones, and MedlinePlus says the A1C test is not used to diagnose it. Your prenatal team will tell you which test you need and when.[1][3]
When should you worry about your blood sugar?
Worry when a lab result crosses into the prediabetes or diabetes range, or when a meter reading is under 70 mg/dL or keeps running high with symptoms. One odd home reading is less important than a pattern, and a lab test is what confirms a problem.[1][11]
| If your result is | What it suggests | Next step |
|---|---|---|
| Fasting 99 mg/dL or below and A1C below 5.7% | Normal | Keep your usual checkups |
| Fasting 100 to 125 mg/dL or A1C 5.7% to 6.4% | Prediabetes | Book a visit to discuss a plan and a recheck |
| Fasting 126 mg/dL or higher or A1C 6.5% or higher | Possible diabetes | See a doctor soon; a second test usually confirms it |
| Any reading 200 mg/dL or higher with thirst and frequent urination | Possible diabetes | Call your doctor the same day |
| Under 70 mg/dL with shaking, sweating or confusion | Low blood sugar | Take fast sugar now and follow your care plan |
| Under 54 mg/dL | Very low blood sugar | Needs action right away |
Sources for the decision table: NIDDK diagnosis cutoffs, the ADA 2026 low glucose levels and the NIDDK low glucose page.[1][4][11]
See a doctor right away if:
- you feel shaky, sweaty, dizzy or confused and your reading is low, or you cannot raise it[11]
- you have a reading under 54 mg/dL[4]
- you have high readings along with feeling very thirsty and needing to urinate more often[1]
- someone with diabetes needed glucagon for a low: call 911 right away[11]
If you have frequent lows, our guide to low blood sugar symptoms, their causes and what to do right away walks through the steps.
Can low blood sugar happen without diabetes?
Low blood sugar is not common in people without diabetes, and when it happens there is usually another cause. MedlinePlus lists liver or kidney disease, adrenal or pituitary problems, an underactive thyroid, poor nutrition, some medicines and alcohol use disorder.[2]
Healthy people do get brief dips. In the 2019 sensor study, 28% of healthy volunteers had at least one low episode, and the group spent about 15 minutes a day under 70 mg/dL.[5]
The NIDDK lists the usual signs as feeling shaky, sweaty, hungry, dizzy or confused, or having a fast heartbeat. Repeated symptoms like these are worth a doctor visit, whether or not you have diabetes.[11]
How do you check your blood sugar at home?
A fingerstick meter or a continuous glucose monitor (CGM) can track your levels at home, but neither one can diagnose diabetes. The NIDDK says a diagnosis needs a lab test, and the result is usually confirmed with a second test.[1][2]
A meter gives one reading from a drop of blood. A CGM uses a small sensor under the skin and reads glucose every few minutes, which shows how meals, activity and sleep move your numbers.[2]
For people with diabetes who use a CGM, the ADA goal for most adults is more than 70% of the day between 70 and 180 mg/dL, and less than 4% of the day under 70.[4]
Do supplements bring blood sugar back to normal?
No supplement has been shown to bring blood sugar back to normal, and NCCIH says the evidence for chromium, cinnamon and berberine is weak. It describes only weak evidence of a possible benefit for these, and none of them is a replacement for medical care.[12]
NCCIH also passes on FDA warnings about products sold as a “natural diabetes cure”, which it says are marketed illegally. It adds that berberine may interact with some medicines, so people who take medicines should talk with a health care provider first.[12]
You can find our other evidence reviews in the blood sugar support guides, each rated against the same standard.
What doctors use first
Doctors start with lab tests: the A1C, a fasting plasma glucose or a glucose tolerance test, and they usually repeat an abnormal result before making a diagnosis.[1]
For people who have diabetes, goals are set one person at a time. The ADA recommends an A1C under 7.0% for most adults and looser goals for older adults with complex health, because lows carry real risk.[4][7]
Practical checklist
- Fast for at least 8 hours before a fasting glucose test, water only.[1]
- Ask for your A1C at your next checkup if you have never had one.[3]
- Compare lab results with the NIDDK cutoffs: under 100 fasting and under 5.7% A1C.[1]
- Tell your doctor if you have anemia, which can make an A1C less accurate.[3]
- Write down home readings with the time and what you ate, and bring the log to your visit.[2]
- Check any supplement against our review standards and with your doctor before taking it.[12]
Bottom line
For adults, normal means fasting at 99 mg/dL or below, under 140 mg/dL two hours after a glucose drink and an A1C under 5.7%. Healthy people sit near 98 to 99 mg/dL most of the day, with a small rise after age 60.[1][5]
For most people, a fasting test plus an A1C at a routine checkup is the better first step than buying a home monitor, because only a lab test can tell you whether a number is a problem.[1]
Frequently asked questions
What is the normal blood sugar range for adults?
For adults without diabetes, the normal range is 99 mg/dL or below when fasting and 139 mg/dL or below two hours after a glucose drink. During a normal day, healthy people spend most of their time between 70 and 140 mg/dL.
Is a fasting glucose level of 100 normal?
A fasting result of exactly 100 mg/dL sits at the bottom of the prediabetes range, which runs from 100 to 125. One reading is not a diagnosis. Ask your doctor about a repeat test or an A1C to check the pattern.
How do I read a blood glucose levels chart?
Find the test you had, such as fasting glucose, A1C or the two-hour glucose test, then match your number to the column. Each test has its own normal, prediabetes and diabetes range, so compare like with like.
Do normal glucose levels change with age?
The diagnostic cutoffs stay the same for all adults. Studies of healthy people show small rises with age: average sensor glucose was 104 mg/dL after 60 compared with 98 to 99 in younger groups, and A1C creeps up slowly each year.
Can stress or illness raise blood sugar?
Yes. MedlinePlus lists stress from surgery, very serious illness or injury as causes of high blood sugar, along with some medicines and thyroid, pancreas or adrenal problems. A doctor may repeat the test once you have recovered.
Sources
- Diabetes Tests and Diagnosis. NIDDK, National Institutes of Health
- Blood Glucose Test. MedlinePlus, National Library of Medicine
- Hemoglobin A1C (HbA1c) Test. MedlinePlus, National Library of Medicine
- Glycemic Goals, Hypoglycemia, and Hyperglycemic Crises: Standards of Care in Diabetes 2026. American Diabetes Association, Diabetes Care, 2026
- Continuous Glucose Monitoring Profiles in Healthy Nondiabetic Participants: A Multicenter Prospective Study. Shah et al., J Clin Endocrinol Metab, 2019
- Effect of Aging on A1C Levels in Individuals Without Diabetes. Pani et al., Diabetes Care, 2008
- Older Adults: Standards of Care in Diabetes 2026. American Diabetes Association, Diabetes Care, 2026
- Children and Adolescents: Standards of Care in Diabetes 2026. American Diabetes Association, Diabetes Care, 2026
- Management of Diabetes in Pregnancy: Standards of Care in Diabetes 2026. American Diabetes Association, Diabetes Care, 2026
- Translating the A1C Assay Into Estimated Average Glucose Values. Nathan et al., ADAG Study Group, Diabetes Care, 2008
- Low Blood Glucose (Hypoglycemia). NIDDK, National Institutes of Health
- Diabetes and Dietary Supplements. NCCIH, National Institutes of Health
Maya Ellison is the Reviews Editor at The Well Brew, a slow, plain-language supplement review blog for everyday adults. Maya reads each label in full, sets every dose beside the amounts used in human studies, grades the research with sources such as the NIH Office of Dietary Supplements and NCCIH, and works out the real cost and refund fine print. Maya has no medical credentials and is not a doctor, dietitian, nurse or pharmacist. Reviews give pros, cons and who a product suits, never scores. How we review supplements.
This article is general information, not medical advice. Dietary supplements are not reviewed by the FDA for safety or effectiveness before they are sold. Talk to your doctor before you start any supplement, especially if you are pregnant, nursing, take medication or have a health condition.