Guide: numbers
Blood Sugar Numbers: What Your A1C and Fasting Glucose Results Mean
Blood sugar numbers are lab results that place your glucose in a normal, prediabetes or diabetes range. Per NIDDK, an A1C below 5.7% and a fasting glucose below 100 mg/dL are normal. A1C of 5.7-6.4% or fasting of 100-125 mg/dL is prediabetes. At 6.5% or 126 mg/dL and above, a doctor confirms diabetes with a repeat test.
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The ranges01
What are normal blood sugar numbers?
Normal blood sugar numbers are an A1C below 5.7% and a fasting plasma glucose below 100 mg/dL. Those cutoffs come from NIDDK, part of the NIH (NIDDK, Diabetes & Prediabetes Tests).
Labs use two common tests. A1C is a percent that reflects your average glucose over time. Fasting glucose is a single reading in mg/dL, taken before you eat.
Type either number into the finder below to see which range it falls in.
- NormalA1C below 5.7%Fasting below 100 mg/dL
- PrediabetesA1C 5.7-6.4%Fasting 100-125 mg/dL
- Diabetes rangeA1C 6.5% or higherFasting 126 mg/dL or higher
Type an A1C or a fasting number to see its range. One test is not a diagnosis; a doctor confirms with a repeat test.
Ranges from NIDDK (NIDDK, Diabetes & Prediabetes Tests). About 115.2 million U.S. adults have prediabetes, and many of them are unaware of it (CDC, National Diabetes Statistics Report). A home meter does not give a diagnosis.
A1C02
What are the A1C ranges for prediabetes and diabetes?
The A1C ranges are: below 5.7% normal, 5.7% to 6.4% prediabetes, and 6.5% or higher in the diabetes range (NIDDK, Diabetes & Prediabetes Tests).
The steps between ranges are small. A result of 5.6% is normal, while 5.7% is not. That is why doctors look at the trend, not just one figure.
A third test, the 2-hour oral glucose tolerance test, measures glucose two hours after a sugary drink. Its cutoffs sit in the same table.
| Test | Normal | Prediabetes | Diabetes range |
|---|---|---|---|
| A1C | Below 5.7% | 5.7-6.4% | 6.5% or higher |
| Fasting plasma glucose | Below 100 mg/dL | 100-125 mg/dL | 126 mg/dL or higher |
| 2-hour glucose tolerance | Below 140 mg/dL | 140-199 mg/dL | 200 mg/dL or higher |
A diabetes diagnosis needs confirmation, usually with a second test (NIDDK, Diabetes & Prediabetes Tests).
Fasting glucose03
What fasting glucose level is normal, and what is high?
A normal fasting glucose is below 100 mg/dL. From 100 to 125 mg/dL is the prediabetes range, and 126 mg/dL or more is the diabetes range (NIDDK, Diabetes & Prediabetes Tests).
Fasting means no food or sugary drinks before the blood draw, so the result shows your baseline. Your clinic will tell you how long to fast.
A worked example: a reading of 104 mg/dL is 4 points into the prediabetes range. It is a reason to retest and talk about habits, not a reason to panic.
One test04
Why does one high blood sugar number need a repeat test?
One high number needs a repeat because a diagnosis of diabetes requires confirmation. NIDDK lists that step as part of the standard (NIDDK, Diabetes & Prediabetes Tests).
A single result can be off for ordinary reasons, such as a fast that was not complete. A second test on another day, or a different test, settles it.
Home meters help people already diagnosed track their day. They are not used to diagnose diabetes, so bring any home readings to a lab visit instead of judging them alone.
By the numbers05
How many Americans have diabetes or prediabetes?
About 40.1 million people in the U.S. have diabetes, or 12.0% of the population, based on 2023 data from the CDC (CDC, National Diabetes Statistics Report).
About 11.0 million of those adults do not know they have it. Another 115.2 million adults have prediabetes.
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See packsSymptoms06
What are the symptoms of high blood sugar?
The common symptoms of high blood sugar are frequent urination, strong thirst and hunger, weight loss you did not plan, tiredness, blurry vision and frequent infections (CDC, Symptoms of Diabetes).
Type 2 diabetes can also bring slow-healing sores and numbness or tingling in the hands or feet.
Many people with prediabetes feel nothing at all. That is why a blood test, not a symptom list, is the way to know your blood sugar numbers.
Thirst and urination
Drinking more and going more often, day and night.
Tired and blurry
Fatigue that does not lift, and vision that blurs.
Slow healing
Cuts that linger, infections that return, tingling feet.
See a doctor07
When should you see a doctor about your blood sugar numbers?
See a doctor if a lab result lands in the prediabetes or diabetes range, if you have the symptoms above, or if you have never had your glucose checked.
Already on insulin or a sulfonylurea? Readings under 70 mg/dL count as a low for many people and need fast sugar right away (NIDDK, Low Blood Glucose).
Book a lab test
Ask for an A1C or a fasting glucose. Both are routine blood draws.
Bring your list
Write down every medicine and supplement you take, with doses.
Ask about next steps
Ask when to retest, and whether a lifestyle program fits you. More on that in insulin resistance basics.
Call 911 if someone with a low passes out, has a seizure or cannot safely swallow (NIDDK, Low Blood Glucose). Never put food or drink in the mouth of a person who is not awake.
Supplements08
Can a supplement change your A1C or fasting glucose?
No supplement has been shown to reliably change A1C. Across 16 ginseng trials, fasting glucose dipped about 5.6 mg/dL with no A1C change (Shishtar et al., PLoS One 2014).
Glyco Defender drops have not been tested on either number. A daily dropper carries 7 mcg of chromium; glucose trials gave 200 to 1,000 mcg a day (NIH ODS, Chromium).
Lifestyle change did far better: it cut type 2 risk by 58% in the Diabetes Prevention Program (NIDDK, Diabetes Prevention Program). Keep taking prescribed medicine, and read how blood sugar supplements are judged and supplements and diabetes medicines.
FAQ09
Blood sugar numbers: quick questions
Is an A1C of 5.7% prediabetes?
Yes. NIDDK puts an A1C of 5.7% to 6.4% in the prediabetes range (NIDDK, Diabetes & Prediabetes Tests). Below 5.7% is normal. A result right at 5.7% is a reason to retest and talk about habits with your doctor, not a diagnosis of diabetes.
What fasting glucose level is too high?
A fasting glucose of 100 to 125 mg/dL is the prediabetes range, and 126 mg/dL or higher is the diabetes range (NIDDK, Diabetes & Prediabetes Tests). A doctor confirms a diabetes result with a repeat test before making a diagnosis.
Can a home glucose meter diagnose diabetes?
No. Home meters help people who already have a diagnosis track daily readings. A diagnosis rests on lab tests such as A1C or fasting plasma glucose, confirmed with a second result (NIDDK, Diabetes & Prediabetes Tests). Bring home readings to your appointment.
What blood sugar number counts as a low?
For many people with diabetes, a reading below 70 mg/dL is low (NIDDK, Low Blood Glucose). Signs include shaking, sweating, hunger and confusion. Take 15-20 g of fast carbohydrate and recheck in 15 minutes.
How many U.S. adults have undiagnosed diabetes?
About 11.0 million U.S. adults have diabetes and do not know it, according to the CDC's 2023 data (CDC, National Diabetes Statistics Report). That is part of the 40.1 million people with diabetes in total.
What is a normal 2-hour glucose tolerance result?
Below 140 mg/dL is normal. A result of 140 to 199 mg/dL is the prediabetes range, and 200 mg/dL or higher is the diabetes range, per NIDDK (NIDDK, Diabetes & Prediabetes Tests). The test measures glucose two hours after a sweet drink.
Can Glyco Defender drops change my A1C?
There is no evidence that they do. No trial has tested Glyco Defender, and ginseng, one of its ingredients, showed no A1C change across 16 trials at doses far above the drops (Shishtar et al., PLoS One 2014). Retest with your doctor instead.
Who wrote this10
Written and reviewed by
Pages built from the label, the sales page and linked NIH, FDA, CDC, FTC and peer-reviewed sources.
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