Fasting Blood Glucose Category Calculator
Enter a fasting blood glucose reading to see its category — low, normal, prediabetes or diabetes — with a mg/dL and mmol/L conversion.
How it works
mmol/L = mg/dL ÷ 18 · Category by fasting mg/dL: <70 low · 70–99 normal · 100–125 prediabetes · ≥126 diabetes
Fasting blood glucose is measured after at least eight hours without food and is a standard screening value. The commonly used thresholds classify readings as normal (70–99 mg/dL), prediabetes (100–125 mg/dL) or diabetes (126 mg/dL or above), while readings under 70 mg/dL fall in the low range. The mg/dL and mmol/L scales measure the same thing — divide by 18 to convert from mg/dL to mmol/L.
Worked example
A reading of 95 mg/dL divided by 18 is 5.3 mmol/L. Because 95 sits between 70 and 99, it is classified as normal.
Frequently asked questions
Does one high reading mean I have diabetes?
No. A single reading can be affected by illness, stress, timing and measurement error. Diagnosis requires repeat testing and clinical interpretation by a healthcare professional — use this tool for context only.
How do I convert between mg/dL and mmol/L?
Divide mg/dL by 18 to get mmol/L, or multiply mmol/L by 18 to get mg/dL. So 100 mg/dL is about 5.6 mmol/L.
What is the difference between fasting glucose and A1c?
Fasting glucose is a snapshot at one moment after fasting, while A1c reflects average blood sugar over roughly the past two to three months. Doctors often use both together.
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Educational estimate only — not medical advice, diagnosis, or treatment. Individual needs vary; consult a qualified healthcare professional for decisions about hydration, nutrition, medication, or substance use.