finger prick check

High blood sugar

What is high blood sugar?

Hyperglycemia (or high blood sugar) occurs when there are high levels of glucose in the blood stream. High blood sugar usually occurs when the body does not have enough insulin or when the body can’t use insulin effectively. Insulin is a hormone (made by the pancreas) that is important for controlling glucose transport and sugar levels in the blood.

When a person is experiencing hyperglycemia, it means their blood glucose is greater than 6.9mmol/L (millimoles per litre) while fasting. Or greater than 10mmol/L two hours after eating.

Blood Glucose Levels

< 3.9
< 3.9
3.9 - 5.5
3.9 - 7.8
5.6 - 6.9
7.9 - 11
Diabetes Risk
> 7.0
> 11.1

Hyperglycemia typically affects people who have diabetes. If the condition is left untreated it can lead to serious complications including damage to tissues, organs, nerves and blood vessels. This can increase your risk of heart attack and stroke, impair eyesight and/or cause damage to the kidneys.

What are the symptoms of hyperglycemia?

The symptoms of high blood sugar can develop slowly over several days or even weeks. Symptoms will typically worsen the longer the blood sugar levels stay high. Recognising signs of hyperglycemia at its early stage can ensure you get the help you need promptly.

In its early stage, symptoms can include:

  • Frequent urination
  • High blood glucose
  • Increased thirst and/or hunger
  • Blurred vision
  • Fatigue
  • Headache

Additional symptoms may include:

  • Weight loss
  • Vaginal and skin infections
  • Slow-healing cuts and sores

If left untreated it can develop into ketoacidosis, where ketones (toxic acids) build up in the blood. Urgent medical assistance is needed.

Symptoms of ketoacidosis include:

What causes hyperglycemia?

Hyperglycemia (high blood sugar) can be caused by a number of factors. Glucose is the main source of energy for your body. After you eat, glucose is absorbed into the bloodstream during digestion. When the glucose level in your blood rises, it triggers the pancreas to release insulin. The insulin helps move the sugar from the blood into your cells. This process lowers the amount of glucose in your blood stream and prevents it from reaching dangerous levels and developing into hyperglycemia.

Typically, hyperglycemia can be caused by;

What are the risk factors for hyperglycemia?

The risk factors for hyperglycemia include:

How is hyperglycemia diagnosed?

High blood sugar is usually diagnosed in one of the following ways;

A fasting blood glucose test is a simple way to measure the levels of sugar in the blood. This test is recommended for people over 35 years of age and should be repeated approximately every three years.

The HBA1C test, also known as the A1C or glycosylated hemoglobin test, is a blood test that would be ordered by a GP or physician. It indicates your average blood sugar levels for the past two to three months. It is a broader test used to diagnose and monitor diabetes. If you’re overweight or obese and you have risk factor(s) for developing type 2 diabetes, your doctor may order an HBA1C test.

An oral glucose tolerance test measures the body’s ability to metabolise sugar and clear it from the bloodstream. This test involves drinking a syrupy solution after fasting. The glucose tolerance test is typically used to diagnose gestational diabetes (diabetes during pregnancy) or prediabetes.

For type 1 diabetics, a continuous glucose monitor can automatically track blood sugar levels to gain insight into patterns and trends throughout the day and night. It uses a sensor inserted under the skin and transmits blood sugar readings to a smartphone or smart device. It sounds an alert when blood sugar levels are too high or too low.

Exercise, food, medications and stress can affect your blood sugar levels. If you have diabetes, a home glucometer can be used to measure the varying amounts of glucose in your blood. A small test strip is inserted into the glucometer. Then a droplet of blood is placed on the strip, usually from a fingertip prick. The glucometer can provide a result in just a few seconds.

How is high blood sugar treated?

High blood sugar can be a serious problem if it’s not treated rapidly. Early treatment and management of hyperglycemia aims to reduce the risk of short-term complications such as those mentioned above, and long-term complications like heart disease, stroke, hypertension, kidney disease and vision loss.

To keep your blood glucose level within an optimal range, your doctor may recommend the following:

Remember, severe hyperglycemia requires urgent treatment. If you have signs or symptoms of ketoacidosis such as vomiting, dehydration or breath that smells fruity, emergency treatment may be required to bring your blood sugar level back to a normal range. This typically involves fluid replacement, electrolyte replacement and insulin therapy.

How can I prevent high blood sugar?

The best ways to prevent hyperglycemia and diabetes from developing in the first place include:

Acknowledgement of Country

The Victor Chang Cardiac Research Institute acknowledges Traditional Owners of Country throughout Australia and recognises the continuing connection to lands, waters and communities. We pay our respect to Aboriginal and Torres Strait Islander cultures; and to Elders past and present.

Victor Chang Cardiac Research Institute - The Home of Heart Research for 30 Years