Last updated:
A1C Normal Range: 5.7%, 6.5%, Prediabetes and Diabetes
A direct guide to normal A1C, prediabetes, diabetes, and what your target may mean in average blood sugar.
Quick A1C calculator
Enter your A1C to convert it to estimated average glucose in mg/dL and mmol/L.
A1C Ranges at a Glance
Quick answer: an A1C below 5.7% is considered normal, 5.7% to 6.4% is the prediabetes range, and 6.5% or higher can indicate diabetes when confirmed by repeat testing or other diagnostic criteria.
The American Diabetes Association (ADA) defines three main A1C categories:
| A1C Level | Classification | Average Blood Sugar |
|---|---|---|
| Below 5.7% | Normal | Under 117 mg/dL (6.5 mmol/L) |
| 5.7% – 6.4% | Prediabetes | 117–137 mg/dL (6.5–7.6 mmol/L) |
| 6.5% or higher | Diabetes | 140+ mg/dL (7.8+ mmol/L) |
These thresholds are based on the relationship between A1C and the risk of developing diabetic retinopathy — the point at which eye damage starts appearing in population studies (International Expert Committee, 2009).
To see exactly what your A1C translates to in average blood sugar, use the A1C calculator.
What Is a "Normal" A1C?
A normal A1C is below 5.7%, which corresponds to an estimated average glucose of under 117 mg/dL (6.5 mmol/L).
But "normal" deserves some nuance:
The Typical Range for Healthy Adults
In people without diabetes, A1C typically falls between 4.0% and 5.6%. Most healthy adults cluster around 5.0–5.4%, which corresponds to an average blood sugar of about 97–108 mg/dL.
| A1C | eAG (mg/dL) | eAG (mmol/L) |
|---|---|---|
| 4.0% | 68 | 3.8 |
| 4.5% | 82 | 4.6 |
| 5.0% | 97 | 5.4 |
| 5.4% | 108 | 6.0 |
| 5.6% | 114 | 6.3 |
For the complete conversion table, visit the HbA1c chart.
Does "Normal" Change With Age?
This is a nuanced question. Strictly speaking, the ADA uses the same 5.7% threshold regardless of age. However, research shows that A1C tends to rise slightly with age even in people without diabetes:
- Ages 20–39: Average A1C around 5.0–5.2%
- Ages 40–59: Average A1C around 5.2–5.4%
- Ages 60+: Average A1C around 5.4–5.6%
This age-related increase appears to be driven by reduced insulin sensitivity, changes in body composition, and slower red blood cell turnover — not necessarily worsening health. A 65-year-old with an A1C of 5.5% is not in the same clinical situation as a 30-year-old with the same result.
A1C of 5.7% — Normal or Not?
An A1C of exactly 5.7% sits right on the boundary. The ADA classifies this as the beginning of prediabetes. In practice, this is a yellow flag, not a diagnosis. If your A1C is 5.7%, your doctor will likely recommend:
- Retesting in 3–6 months
- Fasting glucose and/or oral glucose tolerance test (OGTT) to confirm
- Lifestyle assessment (diet, physical activity, weight)
One reading of 5.7% doesn't mean you have prediabetes. A1C can fluctuate by ±0.5% between tests due to normal biological variation and assay imprecision.
The Prediabetes Range: 5.7% – 6.4%
Prediabetes means your blood sugar is higher than normal but hasn't reached the diabetes threshold. In A1C terms, that's 5.7% to 6.4% — corresponding to average blood sugar of approximately 117–137 mg/dL (6.5–7.6 mmol/L).
Why Prediabetes Matters
Prediabetes is not a benign label:
- Approximately 70% of people with prediabetes eventually develop type 2 diabetes (Tabák et al., 2012)
- Cardiovascular risk is already elevated in the prediabetes range
- But it's reversible. The Diabetes Prevention Program (DPP) trial showed that lifestyle intervention (modest weight loss + 150 min/week of physical activity) reduced progression to diabetes by 58% — more effective than medication (Knowler et al., 2002)
Prediabetes A1C Breakdown
| A1C | eAG (mg/dL) | Risk Level |
|---|---|---|
| 5.7% | 117 | Lower end — monitor closely |
| 5.8% | 120 | Early prediabetes |
| 5.9% | 123 | Early prediabetes |
| 6.0% | 126 | Mid-range prediabetes |
| 6.1% | 128 | Mid-range prediabetes |
| 6.2% | 131 | Higher prediabetes |
| 6.3% | 134 | Higher prediabetes |
| 6.4% | 137 | Upper boundary — highest risk |
Each 0.1% matters in this range. The closer you are to 6.5%, the higher your annual risk of converting to diabetes.
Check your current A1C to average glucose conversion to understand what your number means in daily terms.
The Diabetes Threshold: 6.5% and Above
An A1C of 6.5% or higher on two separate tests meets the ADA criteria for diagnosing diabetes. This corresponds to an average blood sugar of about 140 mg/dL (7.8 mmol/L) or more.
Treatment Targets for People With Diabetes
Once diabetes is diagnosed, the A1C conversation shifts from "what's normal" to "what's my target." The ADA recommends individualizing targets based on the patient's situation:
| Patient Profile | A1C Target | eAG Target |
|---|---|---|
| Most non-pregnant adults | < 7.0% | < 154 mg/dL (8.6 mmol/L) |
| Highly motivated, low hypoglycemia risk | < 6.5% | < 140 mg/dL (7.8 mmol/L) |
| Older adults, complex comorbidities | < 8.0% | < 183 mg/dL (10.2 mmol/L) |
| Pregnancy (preexisting diabetes) | < 6.0–6.5% | < 126–140 mg/dL |
Why Not Target "Normal" A1C for Everyone With Diabetes?
It seems intuitive: if normal is below 5.7%, why not aim for that? Three major trials answered this question:
- ACCORD Trial (2008): Targeting A1C below 6.0% in type 2 diabetes patients increased mortality compared to a standard target of 7.0–7.9%. The trial was stopped early.
- ADVANCE Trial (2008): Targeting A1C below 6.5% reduced kidney complications but did not reduce cardiovascular events or death.
- VADT Trial (2009): Intensive A1C lowering in veterans with type 2 diabetes showed no cardiovascular benefit and increased hypoglycemia.
The lesson: aggressive A1C lowering carries risks — primarily severe hypoglycemia — that can outweigh the benefits, especially in older patients or those with existing cardiovascular disease. That's why targets are personalized, not one-size-fits-all.
A1C Categories: The Complete Picture
| A1C Range | Category | Average Glucose | Action |
|---|---|---|---|
| 4.0–5.6% | Normal | 68–114 mg/dL | Routine screening every 3 years (or more often with risk factors) |
| 5.7–6.4% | Prediabetes | 117–137 mg/dL | Lifestyle changes, retest in 3–6 months, consider metformin if high-risk |
| 6.5–6.9% | Diabetes (near target) | 140–152 mg/dL | Newly diagnosed — lifestyle + possible medication |
| 7.0–7.9% | Diabetes (above target) | 154–181 mg/dL | Review treatment plan, consider intensification |
| 8.0–8.9% | Diabetes (elevated) | 183–209 mg/dL | Medication adjustment likely needed |
| 9.0–9.9% | Diabetes (high) | 212–237 mg/dL | Significant intervention needed |
| ≥ 10.0% | Diabetes (very high) | ≥ 240 mg/dL | Urgent evaluation and treatment intensification |
Special Populations
Children and Adolescents
The ADA recommends an A1C target of < 7.0% for most children and teens with type 1 diabetes. However, the previous target of < 7.5% (used before 2019) is still considered acceptable for children who experience frequent hypoglycemia. CGM-based Time in Range is increasingly used alongside A1C in pediatric diabetes management.
Pregnant Individuals
During pregnancy, tighter glycemic control is critical:
- Gestational diabetes: Target A1C < 6.0% (ideally achieved through diet and exercise)
- Preexisting type 1 or type 2 diabetes: Target A1C < 6.0–6.5% before and during pregnancy
Note that A1C can be artificially lowered during pregnancy due to increased red blood cell production and hemodilution, so it should be interpreted cautiously and supplemented with self-monitored or CGM glucose data.
Older Adults (65+)
For older adults, the risks of hypoglycemia (falls, cognitive impairment, cardiac events) often outweigh the benefits of tight control. The ADA and the American Geriatrics Society recommend:
- Healthy older adults: A1C < 7.0–7.5%
- Complex/intermediate health: A1C < 8.0%
- Very complex/poor health: A1C < 8.5% (avoiding symptomatic hyperglycemia is the primary goal)
Screening Guidelines: When Should You Get Your A1C Tested?
The ADA recommends A1C screening for:
- All adults age 35 and older — every 3 years if results are normal
- Adults under 35 with risk factors — overweight/obesity, family history of diabetes, history of gestational diabetes, polycystic ovary syndrome, physical inactivity, or belonging to a high-risk ethnic group
- People with prediabetes — at least annually
- People with diabetes — every 3–6 months depending on whether treatment goals are being met
If you've just had your A1C tested and want to understand your result, the A1C to average glucose calculator shows you instantly what your number means in everyday blood sugar terms.
Frequently Asked Questions
What A1C is considered "good"?
For someone without diabetes, anything below 5.7% is normal. For someone with diabetes, an A1C below 7.0% is the standard target for most adults — but "good" depends on your individual circumstances, age, and risk of hypoglycemia.
Can I lower my A1C naturally?
Yes, especially if you're in the prediabetes range. Evidence-based strategies include:
- Weight loss: Losing 5–7% of body weight reduced diabetes risk by 58% in the DPP trial
- Physical activity: 150 minutes per week of moderate exercise
- Dietary changes: Reducing refined carbohydrates and added sugars, increasing fiber intake
- Sleep and stress management: Poor sleep and chronic stress contribute to insulin resistance
How much can A1C change in 3 months?
A1C can change significantly in one testing cycle. With medication initiation or major lifestyle changes, drops of 1–2% in 3 months are common. More modest changes of 0.3–0.5% are typical with dietary improvements alone.
Is 5.6% really that different from 5.7%?
Biologically, no — there's minimal difference between 5.6% and 5.7%. The threshold is a clinical convention, not a physiological cliff. However, it does change how your doctor documents and monitors your care. If you're at 5.6%, you're still carrying some risk if you have other metabolic risk factors.
Sources
- American Diabetes Association Professional Practice Committee. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes—2024. Diabetes Care. 2024;47(Suppl 1):S20-S42.
- International Expert Committee. International Expert Committee Report on the Role of the A1C Assay in the Diagnosis of Diabetes. Diabetes Care. 2009;32(7):1327-1334.
- Knowler WC, Barrett-Connor E, Fowler SE, et al. Reduction in the Incidence of Type 2 Diabetes with Lifestyle Intervention or Metformin. N Engl J Med. 2002;346(6):393-403.
- Tabák AG, Herder C, Rathmann W, Brunner EJ, Kivimäki M. Prediabetes: A High-Risk State for Diabetes Development. Lancet. 2012;379(9833):2279-2290.
- Action to Control Cardiovascular Risk in Diabetes Study Group. Effects of Intensive Glucose Lowering in Type 2 Diabetes. N Engl J Med. 2008;358(24):2545-2559.
- ADVANCE Collaborative Group. Intensive Blood Glucose Control and Vascular Outcomes in Patients with Type 2 Diabetes. N Engl J Med. 2008;358(24):2560-2572.
- Duckworth W, Abraira C, Moritz T, et al. Glucose Control and Vascular Complications in Veterans with Type 2 Diabetes. N Engl J Med. 2009;360(2):129-139.
- Nathan DM, Kuenen J, Borg R, et al. Translating the A1C Assay Into Estimated Average Glucose Values. Diabetes Care. 2008;31(8):1473-1478.
- LeRoith D, Biessels GJ, Braithwaite SS, et al. Treatment of Diabetes in Older Adults: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2019;104(5):1520-1574.
This article is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional for diagnosis and treatment decisions.