Blood glucose monitoring and diabetes

Monday, 2 March 2020

When you have diabetes, self-monitoring helps you see the effects of food, exercise, medication and illness on your blood glucose levels (BGLs).

It gives you the opportunity to check in with your body, which then will help you make decisions around:

  • Food (types and quantities)
  • Physical activity (before, during and 24-28 hrs after exercise)
  • Medications especially when you start or change medication
  • Sick day management
  • Driving (Road and Maritime Service recommendation is to have a blood glucose level above 5 to drive)

Nowadays we have more options thanks to technology:

  • Blood glucose meters
  • CGM and flash monitoring
  • HbA1c

Why test?

Understanding your blood glucose levels can help in the early detection and correction of diabetes-related complications. Keeping BGLs within target range will minimise the risk of complications.

How often you monitor and your target range is highly individualised and depends on many factors. In the table below are some general recommendations but you still need to speak with your health team to find out what is the best target for you.

How often to test and target levels

Type 1 diabetes Type 2 diabetes Gestational diabetes
Frequency of monitoring Check before and two hours after meals. At bedtime and during the night if concern about overnight hypoglycaemia.


Monitoring may not be required for everyone. Frequency depends of type of medications and potential side effects. Also, the agreement between you and your health team. Check four or more times a day, depending on your individual requirements.

In pregnancy glycaemic control is tighter to prevent any complications for both mother and baby.

General target levels Fasting 4-8mmol/L

Two hours after meals less than 10mmol/L (from FIRST mouthful)

Fasting 6-8mmol/L

Two hours after meals 6-10mmol/L (from FIRST mouthful)


Fasting less than 5mmol/L

Two hours after meals <6.7mmol/L (from FIRST mouthful)

How to perform a blood glucose check:

  1. Wash your hands in warm soapy water and dry well
  2. Get your meter, strips, tissue and sharp container
  3. Insert test strip in your meter
  4. Prick the finger
  5. Transfer blood to test strip
  6. Repeat if error or not enough blood
  7. Dispose lancets in sharps container
  8. Record your results in a diary

Note: It’s better to prick the side of the fingertip. Glucose reaches your fingertip faster than other sites so it is not advisable to use alternative sites, especially in cases of low blood glucose level.

Troubleshooting problems

If you suspect the reading is wrong, follow these steps:

  • Check the battery isn’t flat
  • Make sure you wash your hands before testing
  • Check your strips aren’t damaged or out of date
  • Try again with more blood
  • Consider whether the meter could have been affected by a change in temperature or humidity
  • Does your meter need to be cleaned?
  • Did you use the same strip more than once?
  • Are you using the correct strip for your meter?

Flash meter

  • It doesn’t measure the blood but it measures the interstitial fluid (fluid in the tissue) through a sensor attached to the back of your upper arm. Readings taken from interstitial fluid have a time lag of five to 10 minutes from a reading using a blood glucose meter.
  • It is not subsidised by NDSS.

Continuous Glucose Monitoring (CGM)

Continuous glucose monitoring is a means of measuring glucose levels continuously in order to gain insight into patterns and trends in glucose levels throughout the day and night.

A CGM sensor is inserted under the skin and measures the level of glucose in the interstitial fluid. The sensor is disposable and changed according to manufacturer recommendations.

A transmitter wirelessly sends the information to a monitor or smart phone.

Special features

  • Alarm when BGL is too high or too low
  • Option to download readings to computer
  • Some models can send information to second person’s smartphone

HbA1c test

The HbA1c blood test reflects the average blood glucose level over the last 10-12 weeks. It’s recommended that you have this test done at least every 12 months, although you may be advised to have it done more often (every three to six months). The results of an HbA1c check can help give you an overall picture of your blood glucose management. The target HbA1c for most people is 7% or less. Your doctor will advise you of the right target for you.

For more information and support call 1300 342 238.

Monitor Smart is a free two-hour program for people with type 2 diabetes that explains all about monitoring and how to understand your results.


By Nader Armaneous, Credentialled Diabetes Educator

Join our community of over 45,000 people living with diabetes