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Hyperglycaemia (high blood sugar)

8-minute read

If you have hyperglycaemia and are worried about symptoms that are getting worse go to the emergency department at the nearest hospital or, call triple zero (000) and ask for an ambulance.

Key facts

  • Hyperglycaemia is when you have too much glucose (sugar) in your blood.
  • People with diabetes can be at risk of hyperglycaemia.
  • Symptoms of hyperglycaemia include feeling thirsty or tired, and needing to urinate (wee) a lot.
  • There are many possible causes such as not having enough insulin or being sick or stressed.
  • If you have type 2 diabetes and your blood sugar is often high, it could lead to long term problems.

What is hyperglycaemia?

Hyperglycaemia is having too much glucose (sugar) in your blood. A blood glucose level above 15mmol/L is considered hyperglycaemia.

What causes hyperglycaemia?

If you have diabetes, this can happen for many reasons, such as:

  • not taking enough insulin or diabetes tablets
  • being less active than usual
  • eating too much carbohydrate food
    • potatoes, bread, pasta, sugary foods and drinks all contain carbohydrates
  • being sick or in pain
  • some medicines, such as steroids
  • being stressed, emotional or excited
  • having an infection (such as thrush, cystitis or a wound infection)
  • drinking too much alcohol

ARE YOU AT RISK? — Are you at risk of type 2 diabetes, heart disease or kidney disease? Use the Risk Checker to find out.

What symptoms are related to hyperglycaemia?

If you have hyperglycaemia, you might:

  • feel very thirsty
  • feel tired or lethargic
  • need to pass urine (wee) frequently
  • have blurred vision
  • find it hard to concentrate
  • feel irritable

If your hyperglycaemia gets worse, you might have diabetic ketoacidosis.

Watch out for:

  • fruity smelling breath
  • nausea and vomiting
  • abdominal pain
  • shortness of breath
  • dry mouth
  • weakness or confusion

CHECK YOUR SYMPTOMS — Use the Symptom Checker and find out if you need to seek medical help.

When should I see my doctor?

If you have type 1 diabetes, it’s important that you act on hyperglycaemia. If not treated, a high blood sugar level can lead to a serious condition called diabetic ketoacidosis.

Call 000 or go to the hospital emergency department if:

  • you cannot keep any food or fluids down
  • your blood glucose level stays above 15mmol/L and you have ketones
  • your symptoms are getting worse and you are unable to manage your condition yourself

Make an appointment to see your doctor if:

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

If your high blood sugar doesn’t go down, or you can’t keep fluids down, see your doctor immediately, or go to your nearest emergency department

If you have type 2 diabetes, an occasional high blood glucose level is not a reason to worry.

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

FIND A HEALTH SERVICE — The Service Finder can help you find doctors, pharmacies, hospitals and other health services.

How is hyperglycaemia diagnosed?

When you are diagnosed with diabetes you will be given a blood glucose meter. If your blood glucose level is higher than your target range, this is high blood sugar.

If your blood glucose level is over 15mmol/L this is hyperglycaemia.

It is normal for your blood glucose levels to vary at different times during the day

If you think that your blood glucose level doesn’t seem quite right, check that:

  • your hands and the meter is clean
  • the test strips are correct and have not expired
  • the battery

ASK YOUR DOCTOR — Preparing for an appointment? Use the Question Builder for general tips on what to ask your GP or specialist.

How is hyperglycaemia treated?

If you have diabetes your doctor has probably given you a diabetes management plan or a sick day plan. Check your plan for advice on what to do when your blood sugar is too high.

You may need to:

  • get extra rest
  • drink plenty of water and avoid drinks containing sugar, alcohol or caffeine
  • check your blood glucose level regularly
  • check your urine (wee) for ketones
  • change your dose of insulin

Can hyperglycaemia be prevented?

If you are living with diabetes, you will sometimes have hyperglycaemia. The following steps will help keep your blood glucose levels in the target range:

  • lifestyle factors
  • take your medicines as prescribed
  • manage stress
  • have a plan for when you get sick

Complications of hyperglycaemia

If you have hyperglycaemia, a short-term complication is dehydration (not having enough fluids in your body).

If you have type 1 diabetes and your blood glucose level is high, you can develop diabetic keto acidosis. You should:

  • check for ketones in your blood or urine
  • follow your sick day action plan

If you have type 2 diabetes and very high blood sugar, you can develop a condition called hyperosmolar hyperglycaemic state.

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

  • heart disease
  • stroke
  • kidney disease
  • vision problems
  • nerve problems

Resources and Support

If you are concerned about your symptoms, you can use healthdirect's online symptom checker. This tool can give you advice on what to do next.

Visit Diabetes Australia to learn more about blood glucose monitoring

The National Diabetes Services Scheme website has information about living with diabetes in multiple languages.

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with 24 hours a day, 7 days a week.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: December 2022

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