To monitor your blood glucose, if you are not using a continuous glucose monitor (CGM)
Generally people with Type 1 diabetes should test themselves every time they give themselves quick acting insulin, so the dose can be adjusted if blood glucose is high. They may also need to measure blood glucose levels before meals and before bedtime.
Testing your blood glucose helps you to:
- monitor your blood glucose to make sure that the amount of insulin you are getting is just right for you
- look for high or low glucose levels so that they can be treated if needed
- monitor and treat diabetes during exercise and illness.
- Learn more about blood glucose testing for type 1 diabetes.
To check your blood glucose, if you are using a CGM
If you are using a CGM and your blood glucose levels go very high or very low, it's important to double-check with a finger prick test before deciding to treat, especially if your symptoms don’t match the CGM readings.
Finger prick tests are still important even if you are using a CGM to monitor your glucose levels. That's because finger prick tests give a more accurate reading of your blood glucose.
- CGMs measure the glucose levels just under your skin, in the interstitial fluid (the fluid that fills the spaces between your cells), while a finger prick test measures the level in your blood. Interstitial glucose levels lag behind blood glucose levels by a few minutes.
- The differences between CGM readings and finger-prick readings will be most noticeable when glucose levels are changing, rather than when they are stable.
- Learn more Can I stop doing finger-prick checks to monitor my blood glucose if I have a CGM?
To monitor your blood ketones
- Your body makes ketones when it’s using fat instead of glucose for energy. This usually happens when your body does not have enough insulin(external link) to help it use glucose for energy. Instead, your body starts burning fat for energy, which releases harmful ketones.
- A build-up of ketones in your body causes your blood to become acidic. This is why it's called ketoacidosis.
- Monitoring blood ketones allows you to find out early if you are developing diabetic ketoacidosis.
- Diabetic ketoacidosis can become life threatening very quickly. It's important to know when to test for ketones and what to do if your ketones are raised.
- Learn more about diabetic ketoacidosis.