Managing Diabetes

More on Home Blood Glucose Monitoring

Why test at all?

Blood testingThe value of blood glucose testing lies in helping you understand what happens to your blood sugars through the day. It also helps you and your diabetes team work out what changes are required. When you attend the diabetes clinic a HbA1c test will give your doctor an idea of your overall control. The HbA1c does not help to decide which of your insulin doses needs to be changed.

Cost of testing

Test strips cost the NHS approximately 35p each. 4 tests a day for a year would cost in the region of 500. For one million people with diabetes this represents 500 million pounds on glucose test strips alone ! This does not take into account the cost of lancets.

You may find your Practice restricts the number of test strips you are given. If you feel you need to test more often discuss this with your doctor. If the extra tests can be justified you are likely to receive as many test strips as you need.

Suitable times for testing

  • Before breakfast – fasting blood sugar
  • 2 hours after breakfast – postprandial blood sugar
  • before lunch
  • 2 hours after lunch – post prandial
  • before your evening meal
  • 2 hours after your evening meal
  • at bedtime
  • 2-3 am to check for nocturnal hypos

Should I test before or after meals?

Blood glucose levels 2 hours after eating a meal are called ‘post-prandial’ levels. In some people with diabetes the glucose concentrations may be quite normal before a meal but can increase considerably after a meal. It is entirely normal for glucose concentrations to increase after a meal. However levels should be less than 8 mmol/l,  two hours after you have a meal.

When should frequency of testing be increased?

  • intercurrent illness (fever, vomiting, diarrhoea, especially if unable to eat)
  • changes in lifestyle or diet increased exercise
  • weight loss or weight gain
  • stress
  • long distance driving
  • when on  Holiday or when travelling crossing time zones
  • poor control
  • frequent hypos
  • change in insulin type or dose
  • when taking certain medications such as steroids
  • those aiming for particularly tight control eg. Before or during pregnancy
  • before undergoing surgery

When should frequency of testing be reduced?

  • blood sugars well controlled and regularly within normal range, HbA1c within 7-7.5%
  • when there has been no change in dose of insulin for more than 3 months
  • sore fingers

Set your goals!

It is useful to agree on goals for blood sugars with your diabetes team. Goals may vary from person to person. For example in an elderly patient who is at risk of hypoglycaemia it may be considered prudent to run the blood sugars at a slightly higher level than in a younger person.

Keep a record

Always keep a written record of your blood glucose concentrations. The readings are intended to show trends in blood sugars which will determine changes in insulin doses. Most modern meters will have a memory capable of retaining over 50 readings. This is not a useful way of storing your readings unless you plan to download them to a computer. When you attend the clinic it is not possible for a doctor or nurse to flick through your readings on the meter. They need to see your blood sugars written down in a suitable diary so that the trends or patterns are clearly visible.  Make sure the time of testing is clearly recorded.

How often should I test?

This is clearly a difficult question to answer as it often varies from person to person. On the one hand having lots of blood sugar readings helps you know more about your blood glucose control.

In many people who make no change in their dose of insulin it makes no sense to test four times a day. The trends or patterns of blood sugar change are often established and do not vary a lot from day to day. If you are in this group we would suggest you test once a day or four times a week provided you test at different times.

Agree a plan with your diabetes team and write down in your blood sugar diary how often you intend to test.

Using the data – ADJUST your doses

There is not much point in testing your blood sugar several times a day if you don’t use the information to make the necessary changes. As a general rule if your blood glucose levels are high at a given time, the dose of insulin which requires adjusting is the preceding dose.

For example if you are high before breakfast, don’t alter your morning dose; you should rather, change your bedtime or evening dose instead.

Who should not test?

People who have well controlled type 2 diabetes on diet or tablets (HbA1c < 7.5%) would not expect to derive any great benefit from blood sugar testing.

Tips for blood sugar testing

  • Wash your hands with soap and warm water before testing. Dry them well.
  • Massage the finger tips to improve blood flow
  • Always use a fresh lancet
  • Use the sides of the fingers
  • Keep your meter clean and free of blood stains

And last of all, if you don’t check your blood sugars don’t make the readings up !


Dr Nishan Wijenaike
Consultant Diabetologist
West Suffolk Diabetes Service
Bury St Edmunds
August 2004