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Low blood sugar (hypoglycaemia) — reference ranges
Glucose below the level the body needs to run properly. Most relevant to people on insulin or certain diabetes medicines, but it can happen to anyone who goes long enough without eating.
| Banda | mmol/L | mg/dL | Qué significa |
|---|---|---|---|
| Level 1 hypo | 3.0-3.8 | 54-69 | The ADA's "alert" range: the body's counter-response is already active. Treat with fast sugar and re-check in 15 minutes. |
| Level 2 hypo | under 3.0 | under 54 | Clinically important: glucose low enough that thinking is measurably affected. Treat immediately. |
| Severe hypo | any low value + needing help | — | Level 3: the person cannot treat themselves — someone else must give sugar or glucagon, or call emergency services. |
Leerlo en contexto
The symptoms come from two systems: the body's adrenaline response (shaking, sweating, fast heartbeat, sudden hunger) and the brain running low (confusion, blurring, irritability, slurring, sleepiness). The adrenaline signs are the warning; by the time the brain signs appear, treatment should already be underway.
The standard treatment is the "rule of 15": about 15 g of fast carbohydrate — roughly four glucose tablets, half a glass of juice or a tablespoon of honey — re-check after 15 minutes, repeat if still low, then eat something longer-lasting once recovered. The dose matters: this is the one situation where fast sugar is exactly right.
People without diabetes can get reactive hypos: a big sugar load, a strong insulin response, and a crash 2-4 hours later. Smaller meals, protein and fibre with the carbohydrate, and not drinking alcohol on an empty stomach usually end the pattern.
Cuándo ver a un clínico
- A hypo that does not respond to repeated treatment — emergency services.
- A severe hypo (needing help) — always worth a medical review afterwards, even if it resolved.
- Repeated hypos in someone without diabetes — the pattern itself is the thing to investigate.
Solo referencia, no un diagnóstico. Los umbrales de esta página son valores OMS y ADA a nivel poblacional; su clínico interpreta sus propios números contra su historia, medicamentos y otras pruebas. Si un valor viene con síntomas, o sigue moviéndose en la dirección equivocada, esa es la señal para actuar — no esta página.