If you are living with type 1 diabetes, checking your blood glucose level (BGL) is important.

For people living with type 2 diabetes, only some will need to monitor their levels, for example if they are changing or adjusting their diabetes medication or insulin.

Monitoring your BGLs helps you see how different factors like food, medicine and activity affect them. Levels can go up and down, for a number of reasons: what we eat, how active we are, any medications we take, and even stress can all affect them. You can use this information to make decisions with your healthcare team to keep your levels within your target range.

In Australia, BGLs are measured in millimoles of glucose per litre of blood (mmol/L). Each person will have their own target level. This will be established by your health care team in consultation with you. It will take into account your age, how long you’ve lived with diabetes, the diabetes medication that you take and any other relevant health conditions you may have. Your team may include a combination of your doctor, Nurse Practitioner or your Credentialed Diabetes Educator (CDE). The team can also consist of a podiatrist, optometrist, dentist and a dietitian. Endocrinologists could be part of the team, especially if a person is living with type 1 diabetes.

FAQs about blood glucose levels

When is the best time to take a fasting measure of blood glucose?

First thing in the morning.

What are the symptoms of low blood glucose levels?

Symptoms include:

  • excessive sweating
  • tiredness
  • lightheadedness
  • feeling dizzy
  • weakness
  • being pale
  • a sudden feeling of excess hunger
  • increased heart rate
  • blurred vision
  • confusion
  • irritability or anxiety.

If you are using insulin and some glucose-lowering diabetes medications, you may be at risk of low blood glucose levels (known as hypos or hypoglycaemia). Having levels below the healthy range can be dangerous for your health if it is not treated.

What is hyperglycaemia?

Hyperglycaemia is a condition where a person has too much glucose in their blood. High blood glucose can occur when the body has too little insulin or when the body is unable to use insulin effectively.

The common causes of hyperglycaemia

Many things can cause high blood glucose (hyperglycaemia). If you don’t have diabetes, it can be caused by family history and genetics, illness or emotional stress.

If you have diabetes, causes of high blood glucose could include:

  • not taking your diabetes medication
  • not doing enough exercise
  • consuming too much carbohydrate
  • drinking too much alcohol 
  • some medicines, such as steroids
  • emotional stress
  • having an infection
  • physical illness.

When should I see my doctor?

It is important to set up a sick day management plan when you are diagnosed with diabetes. The plan is a step-by-step personalised plan that helps people with diabetes manage their levels when they are sick. Illnesses such as the flu, colds or other common infections can affect levels, making it more difficult to manage diabetes.  It is important to be prepared and have a sick day action plan and management kit ready to use at the earliest sign of illness. 

The Australian Diabetes Educators Association (ADEA) recommends working with a Credentialed Diabetes Educator to prepare a Sick Day Kit and keep it up to date. The kit should always include a personal Sick Day Action Plan.

It is important to manage sick days because being unwell can cause the body to release stress hormones that increase the amount of glucose in the bloodstream and make it difficult for insulin to do its job. This can cause levels to rise.

If you have diabetes and are experiencing any of the problems below, call 000 or go to your nearest hospital emergency department:

  • inability to keep any food or fluids down
  • your BGL remains above 15 mmol/L
  • you can’t manage your symptoms and they’re getting worse.

You should make an appointment to see your doctor if:

  • you have diarrhoea or vomiting but are still able to eat and drink
  • you have a fever for more than 24 hours
  • your BGL is above 15 mmol/L even after taking your diabetes medication
  • you are finding it difficult to keep your levels in the target range.

If you often have high levels, this can lead to diabetes complications. You can ask your doctor to review your diabetes management plan.

Treatment options for hyperglycaemia

If you have diabetes, your diabetes management plan should contain advice on what to do when your blood glucose is too high.

You may need to:

  • rest
  • drink plenty of water and avoid drinks containing sugar, alcohol or caffeine
  • check your BGL regularly
  • check your urine for ketones
  • change your dose of insulin.

Hyperglycaemia prevention tips

The following will help keep your blood glucose levels in your target range:

  • eating healthily
  • doing regular physical activity
  • maintaining a healthy weight
  • take your medicines as prescribed
  • managing stress.

Complications of hyperglycaemia

If you have type 1 diabetes, untreated hyperglycaemia can cause harmful acids called ketones to build up in your blood and urine, triggering a serious condition called ketoacidosis.

Symptoms include:

  • feeling very thirsty
  • frequent urination
  • nausea and vomiting
  • abdominal pain
  • shortness of breath
  • having breath that smells of fruit
  • weakness
  • confusion
  • unconsciousness.

If you have type 2 diabetes and very high blood glucose, you can develop a condition called hyperosmolar hyperglycaemic state (HHS). The main symptoms of this are:

  • feeling very thirsty
  • frequent urination
  • confusion.

HHS is a medical emergency.

Other long-term complications of high blood glucose can be serious. Some examples are:


For all people with type 1 diabetes and for some people with type 2 diabetes, monitoring blood glucose levels is very important.

Regular testing with the Australian Type 2 Diabetes Risk Assessment Tool (AUSDRISK) and pathology checks with GPs will help people understand their risk of type 2 diabetes.  Research shows that type 2 diabetes can be prevented in up to 58% of cases of pre-diabetes. It’s important to act quickly—the sooner you start, the sooner your risk level will decrease.

The Life! program can help you take action.

Life! is a free healthy lifestyle program that helps you improve your eating habits, increase your physical activity and manage stress. You can choose from a group course or our telephone health coaching service.

Life! is run by experienced health professionals, including dietitians and exercise physiologists, who guide and support you to make realistic healthy lifestyle changes that suit your needs. The program includes 7 sessions delivered over a 12-month period.

Since 2007, over 75,000 Victorians have learnt more about living a healthy life with the Life! program. It is the largest prevention program of its kind in Australia.

You can take a quick online health test and check your eligibility for the program here


Blood glucose monitoring – Diabetes Australia

Blood glucose target range – Diabetes Australia

Hyperglycaemia and sick day management fact sheet – Baker InstituteHyperglycaemia (high blood sugar) – healthdirect

Hypoglycaemia (low blood sugar) – healthdirect

Blood glucose control (blood sugar levels) – HealthEngine Blog

Blood sugar chart: Target levels, management, risks, and more – Medical News Today

Manage Blood Sugar – Centers for Disease Control and Prevention

My Diabetes Sick Day Action Plan – ADEA

Sick Day Management of Adults with Type 1 Diabetes – ADEA

Type 2 diabetes and sick day management – Baker Institute

Type 2 Diabetes Prevention: How to Prevent Type 2 Diabetes – The Life! program

What is considered a normal blood sugar level? – MyMed