What is HbA1c and what's a good target?

How HbA1c is measured, what each value means in average glucose, and how to read your number in context.

Written by

Carb Lens Editorial

Nutrition writers & product team

Medically reviewed by

Dr. Alicia Nguyen, RD, CDCES

Registered Dietitian · Certified Diabetes Care & Education Specialist · 12+ years clinical experience

Published June 10, 2026 3 min readEditorial policy

HbA1c (or A1c) is a single number that summarizes the past 2–3 months of blood sugar control.

What it measures

Glucose in your bloodstream binds to hemoglobin in your red blood cells. The percentage that's "sugared" gives you HbA1c. Since red cells live 3 months, you get a 90-day average.

Reading the number

HbA1c	Avg glucose (mg/dL)	Avg glucose (mmol/L)
5.0%	97	5.4
5.7%	117	6.5
6.0%	126	7.0
6.5%	140	7.8
7.0%	154	8.6
8.0%	183	10.2
9.0%	212	11.8
10.0%	240	13.4

Targets

**General population**: under 5.7%
**ADA target for diabetes**: under 7.0%
**Tight control (younger, no hypo risk)**: under 6.5%
**Older / high hypo risk**: 7.5–8.0% acceptable

What HbA1c misses

A 7.0% can mean steady 154 mg/dL — or wild swings averaging 154. Two people with the same A1c can have very different cardiovascular risks. CGM data fills in this picture by showing time in range (% of day spent between 70–180 mg/dL).

When testing is unreliable

After a recent blood transfusion
With anemia or other red-cell disorders
During pregnancy
With certain hemoglobin variants (more common in some ethnicities)

In these cases, fructosamine (2–3 week average) is more reliable.

About the author

Carb Lens Editorial — Nutrition writers & product team. The Carb Lens editorial team writes practical, source-checked guides on carbs, blood sugar, and everyday nutrition. Every article is drafted by our writers and cross-referenced against USDA FoodData Central and peer-reviewed clinical guidelines.

How we source and review this article

Nutrition figures come from the USDA FoodData Central database. Blood-sugar and glycemic-load framing follows guidance from the American Diabetes Association and World Health Organization healthy-diet recommendations. Every article is medically reviewed by Dr. Alicia Nguyen, RD, CDCES before publishing and re-checked on a rolling basis. See our full editorial & medical review policy.

This article is for general information and is not a substitute for medical advice. If you're managing diabetes or another condition, always defer to your care team.