Can this result diagnose a condition on its own?

No. Laboratory results are interpreted with symptoms, medical history, sampling conditions, and related tests.

Which reference range or cutoff should I use?

Start with the performing laboratory's report and the purpose of testing; diagnostic cutoffs are separate sourced clinical thresholds.

When should I discuss the result with a healthcare professional?

Results that are clearly outside range, persistent, symptomatic, or unexpected should be reviewed by a healthcare professional.

Information about a laboratory test

High HbA1c: What Does It Mean?

A high A1C is associated with higher average glucose exposure, but anemia, hemoglobin variants, and other conditions can alter the result.

Test summary

Test name: HbA1c
Abbreviations: HbA1c, A1C, Glycated Hemoglobin
Category: Endocrinology / Glucose Metabolism
Panel: Diabetes / Glycemic Monitoring
Specimen: Whole blood
Common units: %, mmol/mol

What does the test measure?

Measures the percentage of hemoglobin with attached glucose and reflects average glucose over roughly the previous 2–3 months.

Why is the test ordered?

Used to diagnose type 2 diabetes and prediabetes and to monitor glycemic control in diabetes.

Information about a low result

A low A1C does not always mean persistently low glucose; conditions that shorten red-cell survival can lower the result.

Information about a high result

A high A1C is associated with higher average glucose exposure, but anemia, hemoglobin variants, and other conditions can alter the result.

Reference and clinical context

A1C diagnostic thresholds are standardized, but anemia, hemoglobin variants, pregnancy, and altered red-cell survival can make the result unreliable.

Reference context 1

< 5.7 %

Population: Nonpregnant adults
Age range: 18
Pregnancy status: No
Specimen: Whole blood

Normal A1C context

The source uses <5.7 % as the threshold for this context. Individual risk and laboratory context still matter.

Reference context 2

>= 5.7 – <= 6.4 %

Population: Nonpregnant adults
Age range: 18
Pregnancy status: No
Specimen: Whole blood

Prediabetes range

This sourced diagnostic threshold of >=5.7–<=6.4 % applies to nonpregnant testing; confirmation is usually required when classic symptoms are absent.

Reference context 3

>= 6.5 %

Population: Nonpregnant adults
Age range: 18
Pregnancy status: No
Specimen: Whole blood

Diabetes diagnostic threshold

This sourced diagnostic threshold of >=6.5 % applies to nonpregnant testing; confirmation is usually required when classic symptoms are absent.

Reference ranges may vary by laboratory, method used, age, sex, pregnancy status, and clinical context. The reference range on your own laboratory report takes precedence.

Interpretation notes

A1C may be unreliable in some pregnancy stages and red-cell/hemoglobin disorders; agreement with glucose measurements matters.

Related specialties

Endocrinology
Internal Medicine
Family Medicine
Pediatric Endocrinology

Frequently asked questions

Sources

Diabetes Tests & Diagnosis — National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
U.S. government medical reference · 2026 · Fasting plasma glucose, A1C, OGTT, random glucose; diagnostic thresholds and pregnancy caveats · Verified: Aug 12, 2026
The A1C Test & Diabetes — National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
U.S. government medical reference · 2026 · A1C meaning, diagnostic use, pregnancy and hemoglobin-related limitations · Verified: Aug 12, 2026
The A1C Test & Race/Ethnicity — National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
U.S. government medical reference · 2026 · Fructosamine as a shorter-term glycemic marker when A1C may be unreliable · Verified: Aug 12, 2026