Hemoglobin A1c (HbA1c)
Average blood sugar over past 2-3 months
21 of 22 providers
Metabolic Health / Glucose
Normal:<5.7%, Prediabetes:5.7-6.4%, Diabetes:≥6.5%
What is Hemoglobin A1c (HbA1c)?
HbA1c (hemoglobin A1c or glycated hemoglobin) measures the percentage of hemoglobin proteins in red blood cells that have glucose molecules attached (glycated). Because red blood cells live ~90-120 days, HbA1c reflects average blood glucose over the past 2-3 months. Unlike fasting glucose (a single snapshot), HbA1c captures long-term glycemic control and is the gold standard for diagnosing and monitoring diabetes. HbA1c ≥6.5%=diabetes;5.7-6.4%=prediabetes;<5.7%=normal (per ADA guidelines).
Here's the critical insight:"normal"HbA1c (<5.7%) is too broad and hides important metabolic risk. HbA1c of 5.5-5.7% (technically "normal") is associated with 2-3x higher risk of developing diabetes over the next decade compared to HbA1c <5.0%. For longevity optimization, target HbA1c <5.0% (ideally 4.5-5.0%)—this reflects tight glycemic control, low oxidative stress, minimal protein glycation, and optimal metabolic health. Populations with exceptional longevity (Okinawans, centenarians) have HbA1c in the 4.5-5.0% range.
HbA1c also reflects glycation burden—the non-enzymatic attachment of glucose to proteins, which causes dysfunction and accelerates aging (advanced glycation end products, or AGEs). Higher HbA1c=more systemic glycation=faster biological aging. HbA1c >5.5% is associated with increased CVD risk, cognitive decline, kidney disease, and all-cause mortality even in non-diabetics.
Why HbA1c Matters for Longevity
- Diabetes diagnosis and monitoring:HbA1c ≥6.5%=diabetes;5.7-6.4%=prediabetes. HbA1c is more convenient than fasting glucose or oral glucose tolerance test (OGTT) and better reflects long-term control. Goal for diabetics:<6.5% (ideally <6.0%).
- Cardiovascular disease:Each 1% increase in HbA1c raises CVD risk by 20-30%, even in non-diabetics. HbA1c >5.5% associated with 40% higher risk of heart attack and stroke. Glycation damages blood vessels, promotes atherosclerosis, impairs endothelial function.
- Microvascular complications (diabetics):High HbA1c causes retinopathy (blindness), nephropathy (kidney failure), neuropathy (nerve damage). Lowering HbA1c from 8% to 7% reduces microvascular complications by 25-35%.
- Cognitive decline and Alzheimer's:Higher HbA1c (even in non-diabetic range) associated with brain atrophy, cognitive decline, and 2-3x higher dementia risk. Glycation of brain proteins impairs function. "Diabetes of the brain."
Optimal vs Standard Ranges
Optimal (Longevity)<5.0%▼
Exceptional glycemic control with lowest CVD risk, mortality, and glycation burden.
Good (Standard)5.0-5.4%▼
Normal glycemic control by standard guidelines with low cardiovascular risk.
Low<4.0%▼
- May indicate hypoglycemia, certain anemias, or blood loss
- Requires evaluation
Elevated5.5-6.4%▼
- Prediabetic range with increased CVD risk and accelerated aging
- ≥6.5% indicates diabetes
Scientific Evidence
Weight Loss (5-10% Body Weight)
Even modest weight loss (5-10% of body weight) significantly lowers HbA1c. Losing 10 kg (22 lbs) reduces HbA1c by 0.5-1.0%. | Visceral fat loss improves insulin sensitivity and reduces hepatic glucose production. | Combine calorie deficit with resistance training to preserve muscle mass.
Resistance training:Builds muscle, which is metabolically active and glucose-hungry. Increases GLUT4 receptors, improving glucose uptake. 3-4x/week. | Aerobic exercise:150 min/week moderate-intensity (brisk walking, cycling) or 75 min/week vigorous (running, HIIT). Lowers HbA1c by 0.3-0.7%. | Post-meal walks:10-15 min walk after meals lowers postprandial glucose by 20-30%, reducing glycation.
Medications (if HbA1c ≥6.5% or prediabetes not responding to lifestyle)
Symptoms of hyperglycemia and diabetes (HbA1c >6.5%):|Polyuria (frequent urination, especially at night)|Polydipsia (excessive thirst)|Polyphagia (increased hunger despite eating)|Unexplained weight loss (type 1 or advanced type 2)|Fatigue, low energy|Blurred vision (glucose-induced lens swelling)|Slow wound healing|Frequent infections (yeast infections, UTIs, skin infections)|Neuropathy:tingling, numbness in hands/feet|Erectile dysfunction (men)
HbA1c 5.7-6.4%=prediabetes (often asymptomatic). HbA1c ≥6.5%=diabetes (symptoms develop gradually).
HbA1c <4.0% may indicate over-treatment with insulin or sulfonylureas, risking dangerous hypoglycemia. Target <5.0% is safe with diet/lifestyle, not with aggressive medications.
Type 2 diabetes:Insulin resistance + progressive beta cell failure. Caused by obesity, sedentary lifestyle, high-carb diet, genetics. Affects 10-12% of US adults.|Type 1 diabetes:Autoimmune destruction of pancreatic beta cells. No insulin production. Typically diagnosed in childhood/adolescence but can occur at any age (LADA=latent autoimmune diabetes in adults).|Prediabetes:Impaired fasting glucose (100-125 mg/dL) or impaired glucose tolerance. HbA1c 5.7-6.4%. Affects 35% of US adults.|Obesity and metabolic syndrome:Visceral fat drives insulin resistance and hyperglycemia.|Sedentary lifestyle:Physical inactivity worsens insulin resistance.|Genetics:Family history of diabetes increases risk 2-6x. Certain ethnicities (South Asian, Hispanic, African American, Native American) higher risk.|Gestational diabetes:Develops during pregnancy, resolves postpartum. 50% of women develop type 2 diabetes within 10 years.|PCOS:Insulin resistance in 70-80% of PCOS cases contributes to hyperglycemia.|Medications:Glucocorticoids (prednisone), atypical antipsychotics (olanzapine), protease inhibitors (HIV meds).|Pancreatic disease:Chronic pancreatitis, pancreatic cancer, cystic fibrosis destroy beta cells.
Source:Type 1 diabetes with excessive insulin:Over-treatment causes frequent hypoglycemia, driving HbA1c too low (<4.5%).|Type 2 diabetes with excessive sulfonylureas or insulin:Risk of hypoglycemia if HbA1c <5.5% while on these medications.|Hemolytic anemia or rapid RBC turnover:Shortened RBC lifespan means less time for glycation, falsely lowering HbA1c. Check fructosamine or continuous glucose monitoring (CGM).|Chronic kidney disease:Uremia can interfere with HbA1c assay (usually falsely lowers it).|Recent blood transfusion:Transfused RBCs haven't been exposed to patient's glucose, falsely lowering HbA1c.
Baseline:Check HbA1c if risk factors for prediabetes/diabetes:overweight/obesity, family history, age >45, PCOS, gestational diabetes history, sedentary lifestyle.|Annual screening:For everyone ≥45 years old. For younger adults if overweight + 1 risk factor (family history, hypertension, dyslipidemia, PCOS).|Every 3 months if diabetic:Monitor glycemic control and adjust medications. Goal:<6.5% (ideally <6.0% if achievable without hypoglycemia).|After lifestyle intervention:Retest 3 months after starting low-carb diet, intermittent fasting, exercise, weight loss. Expect 0.5-1.5% drop with successful intervention.|If prediabetic (5.7-6.4%):Retest every 6-12 months while implementing lifestyle changes to prevent progression to diabetes.|No fasting required:HbA1c can be tested any time of day, regardless of meals (major convenience advantage over fasting glucose).
HbA1c and Diabetes Diagnosis
Source:HbA1c ≥6.5% is diagnostic for diabetes (must be confirmed with repeat test). HbA1c 5.7-6.4%=prediabetes. ADA recommends HbA1c over fasting glucose or OGTT due to convenience (no fasting required) and better reflection of long-term glycemic control. However, HbA1c may miss some cases detected by OGTT (post-meal glucose spikes).
Which Providers Test Hemoglobin A1c (HbA1c)?
Full Provider Comparison
| Provider | Includes | Annual Cost | Biomarkers |
|---|---|---|---|
 Superpower | ✓ | $199 | 100+ (150 with ratios) |
 WHOOP Advanced Labs | ✓ | $349 | 65 |
 Labcorp OnDemand | ✓ | $398 | 30+ |
| ✓ | $486 | 40+ | |
| ✓ | $444 | 288 | |
| ✓ | $349 | 100+ | |
| ✓ | $761 | 54 | |
 Function Health | ✓ | $365 | 160+ |
| ✓ | $250 | 65 | |
| ✓ | $495 | 70+ | |
| ✓ | $895 | 100+ | |
| ✓ | $1950 | 150+ | |
| ✓ | $375 | 80+ | |
| — | $Varies | 75+ | |
| ✓ | $190 | 100+ | |
| ✓ | $99 | 50 | |
| ✓ | $124 | 60 | |
| ✓ | $199 | 50 | |
| ✓ | $499 | 120+ | |
| ✓ | $4188 | 70-80+ | |
| ✓ | $375 | 85 | |
| ✓ | $700 | 128 |
Frequently Asked Questions
What is Hemoglobin A1c (HbA1c)?
Average blood sugar over past 2-3 months
What is the optimal range for Hemoglobin A1c (HbA1c)?
The standard reference range for Hemoglobin A1c (HbA1c) is Normal:<5.7%, Prediabetes:5.7-6.4%, Diabetes:≥6.5%. Optimal ranges may differ based on individual health goals and expert recommendations.
Which blood test providers include Hemoglobin A1c (HbA1c)?
21 out of 22 blood testing providers include Hemoglobin A1c (HbA1c) in their panels. This biomarker is widely available across major providers.
What category does Hemoglobin A1c (HbA1c) fall under?
Hemoglobin A1c (HbA1c) is categorized under Metabolic Health / Glucose. This category includes biomarkers that help assess related aspects of health and wellness.
Medical Disclaimer
This information is for educational purposes only and is not medical advice. Always consult with a qualified healthcare provider about your specific health needs.
Last reviewed:2026-02-20