Blood glucose test

A blood glucose test is a fairly common procedure that's carried out regularly in hospitals, like Great Ormond Street Hospital (GOSH), and clinics. The test is to find out how much glucose (sugar) you have in your blood.

Glucose is one of your body's (especially your brain’s) main sources of fuel, so checking you've got enough to keep you going is essential. Almost anyone can suffer from irregular levels of blood sugar and getting checked out by your doctor is the simplest way to find out why.

How it works

The test doesn't take very long at all, is almost painless and you may not even have to visit your doctor – you can now test your own glucose levels with a home testing kit.

Only a very small sample of blood will be taken to discover whether or not your blood sugar levels are either too high, too low or at a stable level.

The results will come through immediately but may need to be checked in the lab to confirm

Why it's needed

Your body makes hormones to control your blood glucose levels. A hormone called insulin is made in your pancreas (a small organ just below your stomach).

Insulin is the only hormone responsible for lowering your blood glucose levels. It's important that all your hormones are working correctly to ensure you stay healthy.

People with diabetes have changing blood sugar levels because they have difficulty making insulin.

If your blood sugar level is too low

If your blood glucose level is below a certain point you have a condition known as hypoglycaemia.

You can become hypoglycaemic for a number of reasons, such as going for a long time without eating.

If you've been exercising heavily or been drinking alcohol on an empty stomach, this can also result in your blood sugar level dropping.

The symptoms of hypoglycaemia are different for everyone, but you might feel weak, dizzy, hungry or even a bit moody. And if your blood sugar drops really low or very suddenly, you can fall unconscious.

If your blood sugar level is too high

Those who have a blood glucose level that is too high have what's known as hyperglycaemia.

Signs that you might have higher levels of blood sugar are being very thirsty, passing urine frequently, tiredness and weakness.

These can also be signs that you have diabetes, so it's best to get yourself tested if you're experiencing these symptoms.

Last reviewed: Jan 2011

Compiled by:
Great Ormond Street Hospital