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Fasting blood sugar — reference ranges
Glucose measured after at least 8 hours with nothing but water — usually first thing in the morning before breakfast.
| Faixa | mmol/L | mg/dL | O que significa |
|---|---|---|---|
| Normal | 4.0-5.5 | 72-99 | The expected fasting range in a healthy adult. |
| Impaired fasting glucose | 5.6-6.9 | 100-125 | "Prediabetes": higher than normal but not diabetes. A signal to retest and look at the whole picture. |
| Diabetes | 7.0 or above | 126 or above | On two separate tests, a fasting value of 7.0 mmol/L or higher meets the WHO diagnostic criterion for diabetes. |
Ler no contexto
Fasting is the reading most people know because it is the easiest to standardise: nothing but water for at least eight hours, measured before breakfast. One slightly high morning value is not a diagnosis — illness, a bad night, stress and some medicines raise fasting glucose, and the WHO criterion asks for two separate test days.
The "dawn phenomenon" — a normal rise in the last hours of sleep — is why the fasting value is not the same as the true 24-hour average: in some people the body releases glucose to start the day, and the morning reading overshoots.
Quando ver um clínico
- A fasting value at or above 7.0 mmol/L on two separate days — see a clinician for a formal test.
- Repeated values in the 5.6-6.9 range, together with weight, family history or age risk factors — worth a conversation.
- Any value that keeps creeping up month over month, even inside the normal range.
Só referência, não um diagnóstico. Os limiares desta página são valores OMS e ADA ao nível da população; o seu clínico interpreta os seus próprios números contra o seu histórico, medicamentos e outros exames. Se um valor vem com sintomas, ou continua a mover-se na direção errada, esse é o sinal para agir — não esta página.