Blood Glucose 3 tested - mmol/L or mg/dL?
Most meters outside the US show mmol/L. A reading of 3 is far more likely to be 3 mmol/L than 3 mg/dL.
If it is 3 mmol/L
= 54 mg/dL. Fasting without diabetes: Very low · With diabetes before a meal: Level 1 hypoglycemia
Full explanation for 54 mg/dL →If it really is 3 mg/dL
That is 0.2 mmol/L — severely low, below the level 2 hypoglycemia threshold of 54 mg/dL (3.0 mmol/L). Most meters show "LO" below 20 mg/dL. If the person is shaky, sweaty, confused or drowsy, treat it as a severe low: 15–20 g of fast-acting carbohydrate if they can swallow safely; if not, glucagon if available, recovery position and call 911 (US) or your local emergency number.
Full explanation for 3 mg/dL →Treat the low now
- Take 15–20 g of fast-acting carbohydrate (4 glucose tablets, ½ cup (4 oz) of juice or regular soda, 1 tablespoon of sugar or honey).
- Re-check after 15 minutes and repeat if still below 3.9 mmol/L = 70 mg/dL.
- Then eat a snack or your next meal. Do not drive until you are back above 70 and feel normal.
- Without diabetes and without symptoms: eating something and re-checking is usually enough. Mention repeated lows to your doctor.
If you don't have diabetes — reading 3 mmol/L (54 mg/dL)
3 mmol/L (54 mg/dL) is well below normal. In people without diabetes, blood sugar rarely falls this low. If the reading is real and you have symptoms (shakiness, sweating, confusion), treat it now with 15–20 g of fast-acting carbohydrate (see the box above) and see a doctor to find the cause.
Fasting prediabetes cut-off: the ADA uses 5.6 mmol/L (100 mg/dL); the WHO uses 6.1 mmol/L (110 mg/dL). This site follows the ADA.
Fasting (8+ hours without food)
Very low2 hours after eating (or glucose tolerance test)
Very lowIf you have diabetes — reading 3 mmol/L (54 mg/dL)
3 mmol/L (54 mg/dL) is level 1 hypoglycemia (3.0–3.8 mmol/L = 54–69 mg/dL). Treat it now with 15–20 g of fast-acting carbohydrate and re-check after 15 minutes (see the box above).
Before a meal / fasting
Level 1 hypoglycemia1–2 hours after a meal
Level 1 hypoglycemiaTargets for most non-pregnant adults (American Diabetes Association (ADA) Standards of Care). Your own targets may be different — for example in pregnancy, for children, older adults or people prone to lows. See pregnancy targets.
Make sure the number is right
- Wash and dry your hands before a finger-stick: fruit juice or sugar on the skin can raise the result a lot.
- Home meters may differ from a lab value by up to about 15%. At 54 mg/dL that means roughly 46–62 mg/dL.
- CGM sensors measure tissue fluid and lag 5–15 minutes behind blood when glucose changes quickly — confirm lows with a finger-stick.
Check another reading
Nearby values
Sources: ADA Standards of Care · ADA: Hypoglycemia · WHO: Definition and diagnosis of diabetes · MedlinePlus: Blood glucose test
This page explains one reading in general terms. It is not a diagnosis or a treatment instruction. Follow the plan agreed with your doctor or diabetes team.