Key takeaways
- Fasting normal: under 100 mg/dL.
- A1C normal: under 5.7%.
- 2-hour OGTT normal: under 140.
- Many factors affect readings.
- Only a doctor can diagnose.
Understanding your blood sugar numbers helps you have better conversations with your doctor.
Blood sugar ranges (adults)
| Test | Normal | Prediabetes | Diabetes |
|---|---|---|---|
| Fasting glucose | Under 100 mg/dL | 100–125 mg/dL | 126+ mg/dL |
| A1C | Under 5.7% | 5.7–6.4% | 6.5%+ |
| 2-hour OGTT | Under 140 mg/dL | 140–199 mg/dL | 200+ mg/dL |
Source: American Diabetes Association diagnostic criteria. A diagnosis usually needs two abnormal results.
The tests explained
Fasting glucose
Measured after at least 8 hours without food, usually first thing in the morning.
A1C
Shows the percentage of hemoglobin with glucose attached, reflecting your average over about 3 months. No fasting needed.
Oral glucose tolerance test (OGTT)
You drink a sugary solution and your blood sugar is measured 2 hours later.
What affects your numbers
- What and how much you ate
- Physical activity
- Sleep and stress
- Illness or infection
- Medicines such as steroids
- Biotin supplements, which can interfere with some lab tests
Supporting healthy levels
Balanced meals, regular movement, good sleep and stress management are the foundation. Gluco Armor adds daily nutritional support with chromium, magnesium, zinc, biotin and vitamins C and E.
Sources
- American Diabetes Association – "Diagnosis and Classification of Diabetes: Standards of Care in Diabetes," 2024.
- CDC – "Diabetes tests."
- U.S. FDA – "Biotin (vitamin B7): safety communication – may interfere with lab tests."
Common questions
What is a normal fasting blood sugar?
Below 100 mg/dL for adults without diabetes.
What is a normal A1C?
Below 5.7%.
Can biotin affect blood tests?
Yes, tell your doctor and lab if you take biotin.