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Fasting Glucose: Normal Values and What a High Result Means

Fasting glucose measures the level of sugar (glucose) in your blood after an overnight fast. It is one of the primary tests used to screen for and monitor diabetes and pre-diabetes.

Doctor's Assessment Included

Reference Ranges

See the value that applies to you:

Choose male or female — this range differs by sex.

Enter your age — this range changes with age.

This range also depends on context such as cycle phase or sample material; the highlighted rows apply to your group.

Male Your group
mmol/l
Low 3.5 Normal 5.5 High
Female Your group
mmol/l
Low 3.5 Normal 5.5 High

Reference ranges may vary between laboratories. When you order a test, a BIG-registered doctor assesses your personal results in context. For treatment decisions, discuss your results with your GP.

Check your own value

Glucose (Fasting): what this test measures

This test measures blood glucose after fasting for at least 8 hours. It reflects your body's baseline ability to regulate blood sugar without the influence of recent food intake.

Glucose (Fasting): why this value matters

Fasting glucose is a cornerstone of metabolic health assessment. Elevated levels may indicate pre-diabetes or diabetes, while very low levels can also be clinically significant. Consult your healthcare provider for interpretation.

Glucose (Fasting): how to prepare

  1. Come fasting

    Required

    From 22:00 the evening before, eat and drink nothing except water. That is at least 8 hours. Skip coffee, tea, chewing gum and smoking that morning. Plan the draw before 10:00.

  • Water is always fine. Drink as usual beforehand, it makes the draw easier.
  • Take your usual medication, unless your own doctor told you otherwise.

Glucose (Fasting): when is testing worthwhile?

Testing is recommended as part of routine health screening, especially if you have risk factors such as family history of diabetes, overweight, physical inactivity, or a history of gestational diabetes.

Glucose (Fasting): symptoms of a high or low value

Low Levels

Low fasting glucose (hypoglycaemia) may cause shakiness, sweating, confusion, dizziness, rapid heartbeat, and in severe cases, loss of consciousness. Seek immediate medical attention for severe symptoms.

High Levels

High fasting glucose may initially cause no symptoms but over time can lead to increased thirst, frequent urination, fatigue, blurred vision, and slow wound healing.

Glucose (Fasting): what to do about an abnormal value

Male

If Low

Low fasting glucose may indicate hypoglycaemia. Consider evaluation.

If High

Elevated fasting glucose may indicate pre-diabetes or diabetes. Consider HbA1c testing.

Female

If Low

Low fasting glucose may indicate hypoglycaemia. Consider evaluation.

If High

Elevated fasting glucose may indicate pre-diabetes or diabetes. Consider HbA1c testing.

Glucose (Fasting): lifestyle and this value

Maintain a balanced diet with controlled portions, regular physical activity, a healthy weight, and adequate sleep. Limit refined sugars and processed carbohydrates. These lifestyle factors play a key role in blood sugar management.

Glucose (Fasting): frequently asked questions

How long should I fast before this test?

You should fast for at least 8 hours before the test. Water is usually permitted. Follow your healthcare provider's specific instructions.

What fasting glucose level indicates diabetes?

Diagnostic thresholds vary by guideline. Your healthcare provider can interpret your results in context and advise on next steps if levels are elevated.

Can stress affect fasting glucose?

Yes, stress can temporarily raise blood sugar levels through cortisol release. If you were under significant stress during testing, discuss this with your healthcare provider.

Test Products

This marker is included in the following test panels.

Heart & vessels

Heart checkup

An extensive blood test with 12 heart and vessel values — the full cholesterol profile, Apo(B), Lp(a), hsCRP, homocysteine and blood sugar — for insight into your heart and vessel health.

Total Cholesterol LDL Cholesterol HDL Cholesterol Non-HDL Cholesterol Cholesterol/HDL Ratio Triglycerides ApoB (Apolipoprotein B) Lipoprotein(a) hs-CRP (High Sensitivity CRP) Glucose (Fasting) HbA1c (Glycated Hemoglobin) Creatinine
€209,-
General checkup

General checkup

A broad blood test covering 18 values across liver, kidneys, thyroid, heart, vitamins and blood count.

ALT (Alanine Aminotransferase) GGT (Gamma-Glutamyl Transferase) Creatinine eGFR (Estimated Glomerular Filtration Rate) TSH (Thyroid Stimulating Hormone) Total Cholesterol HDL Cholesterol LDL Cholesterol Triglycerides Glucose (Fasting) Vitamin D (25-OH) Vitamin B12 Ferritin Hemoglobin Leukocytes (WBC) Platelets (Thrombocytes) CRP (C-Reactive Protein) MCV (Mean Corpuscular Volume)
€199,-

Medical reviewer

Medical standards

Dr. Naimi oversees the medical standards behind our content and assessments.

Medical policy
CIBG Ministerie van Volksgezondheid,
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Glucose (Fasting)

€7,-