Blood Glucose Monitoring and HbA1c

• Blood glucose testing
• Blood glucose target levels
• HbA1c
• Why test my blood glucose?
• How do I control my blood glucose level?
• What do I do if my blood glucose is high?
• What do I do if my blood glucose is low?
• When should I test my blood glucose?
• How to do a test
• Useful resources

Blood glucose testing

Blood glucose control is very important for people with diabetes.

Checking your blood glucose regularly (using fingerprick testing) shows you how lifestyle changes affect your blood glucose levels and helps you maintain control of your diabetes. High glucose levels increase your risk of developing health issues such as heart, kidney and eye diseases, nerve damage, stroke and poor circulation.

Normal blood glucose ranges for people without diabetes are 3.5–5.5 mmol/L (millimoles per litre) before meals and less than 8 mmol/L two hours after meals. The closer the blood glucose is to ‘normal’, the better.

Self-monitoring (through home fingerprick testing) is most appropriate for:

• people with type 1 diabetes
• people with type 2 diabetes who use insulin and other injectable therapies
• women who are pregnant, and have type 1, type 2 or gestational diabetes

Blood glucose target levels

Blood glucose is checked using fingerprick testing. Blood glucose targets are individual to each person, and you should agree your own target levels with your diabetes care team. The target blood glucose ranges in Table 1 below (from national guidelines) are indicated as a guide only.

Table 1: Target blood glucose ranges

*National Institute of Clinical Excellence (NICE) 2015

** Diabetes UK Council of Health Care Professionals 2015

Why test my blood glucose?

Blood testing is the best way to stay in control of your diabetes because it tells you what is happening at any particular moment. It can help determine if you are at risk of a hypoglycaemic episode (a ‘hypo’) or a hyperglycaemic episode (a ‘hyper’). You should never change any long-term medication you are taking in response to a one-off high or low reading. You should first try to work out if there is a pattern before making any changes and always talk to your diabetes care team first.

How do I control my blood glucose level?

You should control your blood glucose through a balance between food, exercise and medication.

• Eat a healthy diet. 
• Take regular exercise. 
• Understand how insulin works in your body. 

What do I do if my blood glucose is high?

If your blood glucose level is consistently above the target set by your diabetes care team you may be at increased risk of health problems.

Contact your diabetes care team for advice if your blood glucose is often above target. (more information here)

What do I do if my blood glucose is low?

If your blood glucose level is below 4 mmol/L you are at risk of hypoglycaemia. You may require a change in your insulin doses or to make changes to your diet or lifestyle to avoid hypoglycaemia.

Contact your diabetes care team for advice if your blood glucose is often below 4.0–4.5 mmol/L.

When should I test my blood glucose?

When your diabetes is treated with insulin, you will need to test your blood glucose levels regularly. If the results are within your agreed target range then you may be able to test your blood glucose less often.

If your blood glucose levels are not in your agreed target range, you may need to adjust your insulin.

If you use a ‘basal bolus’ insulin regime (i.e. if you adjust the dose of fast-acting insulin on a daily basis depending on your diet and activity levels) then your doctor or nurse may ask you to check your blood glucose more often. If you use this regime, you should monitor your blood glucose before meals, before you go to bed, before you drive and occasionally in the middle of the night so that you can assess your overnight insulin requirements.

If you are on a twice-daily insulin mixture, then at first you should test your blood glucose four times a day (once before each meal and again before bed). This will allow your doctor or nurse to assess the best insulin dose for you.

This may be reduced to before breakfast and before dinner every day, or alternating between this pattern and testing before lunch and before bedtime. 

When should I test my blood glucose more often?

Illness 
Your blood glucose may change in response to illness. If it does, then you should test it more often, around every two to four hours, especially if you are on insulin. Your treatment may need to be changed. Discuss the ‘sick day guidance’ with your diabetes care team – see the Useful resources section at the end of this page.

Steroid therapy 
If you are on steroid therapy, you should test your blood glucose more often. Steroids may increase blood glucose levels. Your treatment may need to be changed.

Before conception and during pregnancy 
You should test your blood glucose more often if you are pregnant or trying to conceive. Blood glucose levels of 4–6 mmol/L are desirable before and during pregnancy. Contact your diabetes care team for advice if you are planning to become pregnant and as soon as you know you are pregnant.

How to do a test 

For a video tutorial of how to conduct a test watch the video below:

• Wash your hands in warm water.
• Prick the side of your finger (this is less painful).
• Massage your finger from base to tip if necessary.
• Place a droplet of blood on the testing strip. You should follow the instructions on the pack precisely and always check the expiry date.
• Check visually or use a blood glucose meter.
• Keep the meter clean and care for it by following the instructions below.
• Record the result in your diary.

How do I look after my blood glucose meter?

• All meters come with instructions. You should read these and follow them closely.
• The manufacturer will normally have a helpline you can call for telephone advice.
• Don’t forget to complete the warranty card and return it to the company.
• It is important to quality-control your meter regularly. You can buy a control solution for doing this.

Where do I get my strips and lancets?

Your GP will be able to prescribe the equipment you need to use your meter.

Be in control

Testing your blood glucose levels regularly is one sure way of finding out what's happening to your body so that you control your diabetes and it doesn’t control you. For further information have a look at Diabetes UK guide about monitoring your blood glucose levels.

HbA1c

When you have a diabetes check-up, a blood sample is taken for the HbA1C (haemoglobin A1c) test. This lets you know what your average blood glucose has been over the previous three months.  Target ranges (from national guidelines) are shown in Table 2 below. Evidence shows that if you can achieve these levels, you will minimise the risk of long-term vascular complications.

Table 2: Target HbA1c ranges

For more information on HbA1C click here.

Useful resources

For information on ‘sick day guidance’ for type 1 diabetes, click here.