What this marker measures
Fasting glucose is one of three standard tests for diabetes screening, alongside the two-hour glucose tolerance test and HbA1c. All three measure blood sugar regulation differently and complement each other.
High or low: what it can mean
High Glucose
Fasting glucose above 100 mg/dL is in the prediabetes range; above 126 mg/dL on two separate occasions meets the diabetes threshold — diagnosis usually requires confirmation and clinical context. A single elevated reading does not settle the picture on its own.
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Low Glucose
Low fasting glucose (hypoglycemia, below 70 mg/dL) can cause symptoms such as shakiness, sweating, or confusion. It can occur with certain medications, prolonged fasting, or, rarely, hormone conditions.
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Lifestyle considerations
- •Regular physical activity improves insulin sensitivity and helps maintain healthy glucose levels
- •Choosing fibre-rich, lower-glycaemic foods reduces post-meal glucose spikes
Frequently asked questions
What is Glucose?
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Blood glucose measures the concentration of sugar in the blood. Fasting glucose is measured after at least 8 hours without eating and is used to screen for diabetes and prediabetes.
What does Glucose measure?
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Fasting glucose is one of three standard tests for diabetes screening, alongside the two-hour glucose tolerance test and HbA1c. All three measure blood sugar regulation differently and complement each other.
What does high Glucose mean?
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Fasting glucose above 100 mg/dL is in the prediabetes range; above 126 mg/dL on two separate occasions meets the diabetes threshold — diagnosis usually requires confirmation and clinical context. A single elevated reading does not settle the picture on its own.
What does low Glucose mean?
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Low fasting glucose (hypoglycemia, below 70 mg/dL) can cause symptoms such as shakiness, sweating, or confusion. It can occur with certain medications, prolonged fasting, or, rarely, hormone conditions.
What supports healthy Glucose levels?
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Regular physical activity improves insulin sensitivity and helps maintain healthy glucose levels. Choosing fibre-rich, lower-glycaemic foods reduces post-meal glucose spikes
Related biomarkers
Editorial note
LabTestly explains lab markers using plain-English educational content. Reference ranges may vary by laboratory and should be interpreted with a clinician.
Educational content · Editorially reviewed for clarity · Last updated
Common sources used for lab-test education
Not medical advice
This page is for general understanding only and does not replace medical advice from your clinician. Reference ranges can vary by laboratory, age, sex, pregnancy status, medications, and clinical context.