What is normal fasting blood sugar?

For venous plasma, 3.9–6.0 mmol / L. 6.1–6.9 is prediabetes, 7.0 and above on repeat tests is a diabetes criterion. Capillary (fingerstick) upper norms are slightly lower. In pregnancy the threshold is stricter — normal below 5.1.

What does HOMA-IR mean?

It’s an insulin-resistance index from fasting glucose and insulin: HOMA-IR = glucose × insulin / 22.5. Normal is roughly below 2.7; higher indicates reduced insulin sensitivity. The exact cutoff depends on the lab.

Is one high sugar reading diabetes?

No. A single rise can be from stress, a recent meal or illness. Diagnosis relies on repeat measurements, a glucose tolerance test and HbA1c. A doctor makes the assessment.

Which units to enter?

In mmol / L, as on Russian and most European reports. If yours is in mg / dL, divide by 18 (e.g. 100 mg / dL ≈ 5.6 mmol / L).

Blood sugar and HbA1c norms

Enter glucose from a blood test and say when it was taken — fasting or after a meal: the calculator checks it against the norm and shows whether it’s normal, prediabetes or diabetes. You can also convert HbA1c into average glucose and compute the HOMA-IR insulin-resistance index. Values are in mmol / L, as on Russian and most European reports.

Check glucose, HbA1c and HOMA-IR

Enter glucose or HbA1c — the result appears instantly.

Glucose and HbA1c norms

Venous plasma, mmol / L (WHO). In pregnancy thresholds are stricter (fasting normal below 5.1). HbA1c is in percent.

Marker	Norm
Fasting glucose	3.9–6.0 mmol / L
2 h after a meal	below 7.8 mmol / L
Prediabetes (fasting)	6.1–6.9 mmol / L
Diabetes (fasting)	7.0 and above
HbA1c (normal)	below 5.7 %
HOMA-IR (normal)	below 2.7

Normal glucose fasting and after a meal

Fasting (8+ hours without food) normal venous-plasma glucose is 3.9–6.0 mmol / L. Values of 6.1–6.9 are prediabetes (impaired fasting glucose); 7.0 or above on two tests is a diabetes criterion. Two hours after a meal the norm is below 7.8; 7.8–11.0 is impaired tolerance, 11.1 or above is diabetes.

A single high result isn’t a diagnosis: sugar is affected by stress, a recent meal and illness. Diagnosis relies on repeat tests and HbA1c.

HbA1c and average glucose

HbA1c reflects your average blood sugar over the past 2–3 months, in percent. Normal is below 5.7%; 5.7–6.4% is prediabetes; 6.5% and above is diabetes. The calculator converts HbA1c into the familiar average glucose (eAG) in mmol / L so the result is easier to grasp.

HOMA-IR index (insulin resistance)

HOMA-IR estimates how well cells respond to insulin. It’s computed from fasting glucose and fasting insulin: HOMA-IR = glucose × insulin / 22.5. A normal guide is below 2.7; higher suggests insulin resistance — an early stage toward type 2 diabetes that lifestyle can often reverse.

Frequently asked questions

For venous plasma, 3.9–6.0 mmol / L. 6.1–6.9 is prediabetes, 7.0 and above on repeat tests is a diabetes criterion. Capillary (fingerstick) upper norms are slightly lower. In pregnancy the threshold is stricter — normal below 5.1.
Glycated hemoglobin reflects average sugar over 2–3 months. Normal is below 5.7%, 5.7–6.4% is prediabetes, 6.5% and above is diabetes. The calculator converts HbA1c into average glucose in mmol / L.
It’s an insulin-resistance index from fasting glucose and insulin: HOMA-IR = glucose × insulin / 22.5. Normal is roughly below 2.7; higher indicates reduced insulin sensitivity. The exact cutoff depends on the lab.
No. A single rise can be from stress, a recent meal or illness. Diagnosis relies on repeat measurements, a glucose tolerance test and HbA1c. A doctor makes the assessment.
In mmol / L, as on Russian and most European reports. If yours is in mg / dL, divide by 18 (e.g. 100 mg / dL ≈ 5.6 mmol / L).

Sugar is part of the bigger metabolic picture

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Decode my sugar test

This calculator is for reference and information only and is not a diagnosis. A diagnosis of prediabetes or diabetes is made by a doctor from repeat tests.