What is high blood sugar?

For a person with diabetes, high blood sugar (or hyperglycemia) is a fact of life.

The symptoms of high blood sugar levels can include:

  • tiredness
  • blurred vision
  • thirst
  • frequency of urination
  • weight loss

If blood sugars get very high, people with diabetes are at risk for diabetic ketoacidosis, which can be very serious.


In type 1 diabetes, where the body cannot use the sugar for fuel due to a lack of insulin, the body is literally starved and goes elsewhere for fuel. Without access to sugar in the fat cells, your body will begin to directly break down fat to use as fuel. The break down of fat releases energy, but also generates ketones. High levels of ketones usually build up gradually in blood and urine, causing it to become more acidic. This is called ketoacidosis. As a result of this, many of the enzymes that control the body's metabolic processes aren't able to function as well.

Symptoms of diabetic ketoacidosis (DKA) can include:

  • abdominal pain (especially in children)
  • confusion
  • decreased perspiration
  • deep and rapid breathing
  • dry cool skin
  • excessive thirst and urination
  • fatigue
  • high blood glucose
  • nausea and vomiting
  • presence of ketones in the urine
  • rapid weight loss
  • sweet, fruity odour on the breath (it may smell like nail polish remover)

What to do?

If you suspect that you have ketoacidosis based on your symptoms, you should get your blood sugar levels checked. You can also check for ketones in the blood and urine. Contact your diabetes team if you are feeling unwell or have ketones or high blood sugars. Sometimes, depending on the severity of the situation, it is necessary to seek urgent medical attention.