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Blood Sugar Levels Chart

Enter your glucose reading, choose the test type and unit to find out if your level is Normal, Pre-diabetic, or Diabetic.

Test type

Blood Sugar Reference Ranges

Test TypeNormalPre-diabeticDiabeticUnit
Fasting< 100100 – 125≥ 126mg/dL
2-Hour OGTT< 140140 – 199≥ 200mg/dL
HbA1c< 5.75.7 – 6.4≥ 6.5%

Conversion: 1 mmol/L = 18.018 mg/dL. HbA1c is always measured in %. The 2-Hour OGTT thresholds (140/200 mg/dL) apply to the standardized oral glucose tolerance test, not a normal meal.

Understanding Blood Sugar Levels

Blood sugar (glucose) is the body's primary source of energy. It comes from the food you eat and is regulated by insulin, a hormone produced by the pancreas. When this regulation breaks down, blood sugar can remain chronically elevated, leading to pre-diabetes or diabetes.

HbA1c explained

Unlike a single glucose reading, HbA1c measures the percentage of hemoglobin in your blood that has glucose attached. Because red blood cells live for about 3 months, HbA1c gives a reliable picture of your average blood sugar over that period. It is the gold standard for monitoring long-term glucose control.

When to test

  • Fasting: After at least 8 hours of no food or drink (except water). Usually done first thing in the morning.
  • 2-Hour OGTT (Oral Glucose Tolerance Test): Measured 2 hours after drinking a standardized 75 g glucose solution. This is a clinical diagnostic test — thresholds differ from a normal meal.
  • HbA1c: A blood test done every 3-6 months. Does not require fasting.

Frequently Asked Questions

What is a normal blood sugar level?+
A normal fasting blood sugar is below 100 mg/dL (5.6 mmol/L). After eating, levels below 140 mg/dL (7.8 mmol/L) are considered normal for most adults.
What is HbA1c?+
HbA1c (glycated hemoglobin) measures your average blood sugar over the past 2-3 months. It reflects how well your blood sugar has been controlled and is reported as a percentage. A normal HbA1c is below 5.7%.
How often should I test my blood sugar?+
If you have diabetes, your doctor will advise a testing schedule — often multiple times daily. For pre-diabetic individuals, testing may be recommended every 3-6 months. Healthy adults should get checked at least every 3 years, or more often if risk factors are present.
Can diet affect my blood sugar levels?+
Absolutely. Foods high in refined carbohydrates and sugar cause rapid blood sugar spikes. A diet rich in fiber, lean protein, healthy fats, and whole grains helps maintain stable levels. Regular meal timing and portion control also play an important role.

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