Blood Glucose 25 tested - mmol/L or mg/dL?
Most meters outside the US show mmol/L. A reading of 25 is far more likely to be 25 mmol/L than 25 mg/dL.
If it is 25 mmol/L
= 450 mg/dL. Fasting without diabetes: Diabetes range · With diabetes before a meal: Very high
Full explanation for 450 mg/dL →If it really is 25 mg/dL
That is 1.4 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 25 mg/dL →Get medical advice now
- Check ketones if you use insulin. Moderate or high ketones, vomiting, abdominal pain, deep fast breathing or fruity-smelling breath can mean diabetic ketoacidosis — call 911 (US) or your local emergency number or go to the emergency room.
- Very high readings (especially above 33.3 mmol/L = 600 mg/dL, often shown as "HI") with extreme thirst, confusion or drowsiness can mean hyperosmolar hyperglycemic state — an emergency.
- With diabetes and none of these signs: contact your care team today and re-check every 2–3 hours.
- Without known diabetes: see a doctor today — and if you feel unwell (vomiting, very thirsty, drowsy), treat it as an emergency: call 911 (US) or your local emergency number.
If you don't have diabetes — reading 25 mmol/L (450 mg/dL)
25 mmol/L (450 mg/dL) is in the diabetes range whether fasting or after a meal. A random reading of 11.1 mmol/L = 200 mg/dL or more together with typical symptoms (thirst, frequent urination, weight loss) is enough for a diagnosis — see a doctor today. If you feel unwell (vomiting, very thirsty, drowsy), it is an emergency: call 911 (US) or your local emergency number.
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)
Diabetes range2 hours after eating (or glucose tolerance test)
Diabetes rangeIf you have diabetes — reading 25 mmol/L (450 mg/dL)
25 mmol/L (450 mg/dL) is very high. Check ketones if you use insulin and contact your care team today. With moderate or high ketones, vomiting, abdominal pain, deep fast breathing, extreme thirst, confusion or drowsiness, call 911 (US) or your local emergency number (see the box above).
Before a meal / fasting
Very high1–2 hours after a meal
Very highTargets 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 450 mg/dL that means roughly 383–518 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: Hyperglycemia · MedlinePlus: Diabetic ketoacidosis · 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.