What it measures
The amount of glucose, a sugar, in the blood at the moment the sample is taken. It changes through the day with meals, so fasting and non-fasting samples are read differently.
Why people test it
- Measured to check for diabetes and prediabetes, usually on a fasting sample.
- Part of many general health checks, alongside HbA1c and cholesterol.
- Monitored by people with diabetes, or on medicines that can raise blood sugar such as steroids.
- Checked when someone has symptoms such as thirst, passing more urine or tiredness.
Typical range
Ranges vary by lab, method, age and sex, and your report shows the lab's own range. One NHS trust gives 3.5 to 6.0 mmol/L for a fasting sample. Source: Worcestershire Acute Hospitals NHS Trust: Glucose.
Finger-prick or vein?
A vein draw is the usual route, though some kits use a finger-prick. Blood cells keep using glucose after the sample is taken, so labs use a tube with a preservative to hold the level steady.
A fasting glucose result needs a fasting sample, usually taken in the morning.