Blood sugar
Your Blood Sugar Is "Fine." Two Numbers Say Whether It Really Is.
One number is a photo. The other is the movie. Most people only ever see the photo.
Reviewed by Jeffrey Blue, MD · 2 min read · October 15, 2026
The short version
- Normal is a fasting glucose under 100 and an HbA1c under 5.7%.
- Fasting glucose is a snapshot. HbA1c is the three-month average.
- On our scale, two "normal" results can earn very different grades.
The American Diabetes Association lists a fasting glucose under 100 mg/dL and an HbA1c under 5.7% as normal. If you only know one of those numbers, you only have half the picture.
The photo: fasting glucose
Fasting glucose is your blood sugar on the morning of the test, after a night without food. It is useful, and it is also easy to nudge. A short night, a stressful week or a late dinner can move it.
The movie: HbA1c
HbA1c measures how much sugar has attached to your red blood cells over roughly the last three months. It does not care what you ate last night. That makes it a steadier read on the direction you are heading.
Not every routine panel includes it. If yours does not, it is a fair thing to ask your doctor about at your next visit.
Why "under the line" is not the finish line
A fasting glucose of 98 and one of 82 are both under 100. They are not the same result. One is close to the line and one has room to spare. The same goes for an HbA1c of 5.6% compared with 5.1%.
In a 2010 study in the New England Journal of Medicine that followed more than 11,000 adults for about 14 years, risk rose steadily across the HbA1c range, including within the values usually called normal.
Above the normal line, the American Diabetes Association publishes further ranges that doctors use. Results at those levels are worth reviewing with your doctor, and sooner rather than later.
What the guidance points to
The ADA Standards of Care suggest breaking up long stretches of sitting with a few minutes of light movement, and building toward 150 minutes of activity a week. A ten-minute walk after your largest meal is one of the easiest places to start.
How we grade it
This is where "normal" and a grade part ways. On a Body By Numbers report, two fasting glucose results that are both normal on a lab report can earn very different grades, and the same goes for HbA1c. A normal result close to the line is not graded like one with room to spare.
Sources
- Selvin E, et al. Glycated hemoglobin, diabetes, and cardiovascular risk in nondiabetic adults. New England Journal of Medicine, 2010.
- American Diabetes Association. Standards of Care in Diabetes: Classification and Diagnosis; Facilitating Positive Health Behaviors.
This article is general information, not medical advice. Make decisions about your care with your own doctor.