Testing your own blood glucose, and target levels

Testing your own blood glucose, and target levels

Having high blood glucose makes you more likely to get other health problems, so keeping your glucose levels as close to normal as possible is very important. Your diabetes care team will help you with this.

You will need to test your blood glucose several times a day, to make sure it doesn't get too high or too low – this is called self‑monitoring. It is done using a simple finger prick test with a home‑testing kit. Your care team should make sure you have all the equipment you need, as well as teaching you how to use the kit and act on the results.

If you are pregnant, when you need to test and your target levels may be different from those given below – see the NICE guidance on diabetes in pregnancy (see other NICE guidance).

How often to test

You should test your blood glucose at least 4 times a day – before each meal and before you go to bed. You might need to test more often, such as before and during driving, when you exercise, if you start to feel unwell, during illness (as part of sick-day rules) or if you have problems with hypos.

Target blood glucose levels

Blood glucose levels are given in a unit of measurement that is written as 'mmol/litre' or 'mmol/l'.

To minimise your risk of long‑term problems caused by blood glucose levels that are higher than normal, you should aim for the following target levels:

  • between 5 and 7 mmol/litre before breakfast ('fasting' level)

  • between 4 and 7 mmol/litre before meals at other times of the day.

If you have to test after a meal, the target level at least 90 minutes after eating is between 5 and 9 mmol/litre.

Your diabetes care team should talk with you about your blood glucose targets. This includes what level to aim for before you go to bed, which will depend on when you last ate and your insulin dose.

Continuous glucose monitoring

Most adults with type 1 diabetes don't need continuous glucose monitoring. But you may be offered this if you have problems with hypos.

Questions to ask about testing your blood glucose

  • Why do I need to test my blood glucose?

  • When should I test?

  • Is it OK to test after a meal rather than before?

  • When might I have to test more often?

  • What are my target blood glucose levels?

  • How do I adjust my insulin dose to meet the targets?

  • Do all of my results need to be in the target range?

  • What can I do if I'm often missing my targets?

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