Hyperglycaemia in diabetes

by | Diabetes

Hyperglycaemia means too much sugar (glucose) in the bloodstream. For someone with known diabetes it is a sign that their diabetes is not well controlled. Hyperglycaemia will happen to most people with diabetes at some point, but it shouldn’t happen every day.

Regulating your blood sugar levels
Under normal circumstances the body secretes insulin to regulate the blood sugar (also known as glucose) level and keep it within a healthy range.

This is how it works: you eat food; the carbohydrates are broken down into sugars (glucose) and passed into the bloodstream. The raised level of sugars in the blood triggers the insulin-secreting cells of the pancreas to release insulin into the bloodstream.

Insulin improves the uptake of glucose from the blood across cell membranes and into the cells of the body, thus taking it out of the circulation. The result is a lowered blood glucose level which then switches off the release of insulin.


Symptoms of high blood sugar include:

  • excessive thirst;
  • passing large volumes of urine, frequently;
  • tiredness or weakness;
  • weight loss; and
  • blurred vision.

People with diabetes often don’t experience symptoms of hyperglycaemia until their blood glucose level is very high. Regular blood glucose checks are therefore important to ensure your blood glucose is well controlled.


Problems taking insulin or diabetes medicine

People with diabetes usually either have to inject insulin or take oral medicines to control their blood glucose level.

People with diabetes must take care not to miss doses of insulin or take too little or they run the risk of becoming hyperglycaemic. The same applies to missing oral diabetes tablets.

Incorrect insulin injection technique (such as not gently swirling insulin vials, as instructed, to mix and re-suspend the particles before injecting) can also lead to hyperglycaemia.


Eating too much (especially eating too many simple carbohydrates) or drinking sugary drinks can make blood sugar levels rise. Make sure you stick to your diabetes healthy eating plan.

Lack of exercise

Regular physical activity helps insulin to work better, and being inactive can contribute to the development of hyperglycaemia.

Mental or emotional stress

Being under stress can cause the release of glucose into the bloodstream and stress hormones can bring about resistance to the action of insulin, both actions contributing to high blood sugar.

Physical stress

Blood sugar levels can be raised by physical stresses, which cause the body to produce more of certain hormones that stimulate the liver to make extra glucose. Such stresses include:

  • being ill;
  • having an infection (such as a chest or urinary tract infection);
  • major physical trauma;
  • undergoing surgery; and
  • severe stresses to the body, such as heart attack or kidney disease.

Other medicines

Medicines such as corticosteroids and antipsychotic medicines can raise your blood sugar level.

Tests and diagnosis

Blood glucose monitoring

Most people with diabetes are advised to test their own blood sugar levels regularly — this is called self-monitoring of blood glucose. They do this by testing a drop of blood obtained by pricking their finger.

Glycosylated haemoglobin (HbA1c) test

Your doctor will also recommend checking your blood sugar control every 3 to 6 months with a glycosylated haemoglobin (HbA1c) blood test. This test measures the amount of haemoglobin (a protein in red blood cells) that has combined with glucose – a measure of blood glucose control over the last few months.

Emergency complications

Diabetic ketoacidosis

People with type 1 diabetes have little or no insulin. In these people hyperglycaemia may happen quickly and progress to diabetic ketoacidosis. Diabetic ketoacidosis is a dangerous condition in which the body starts to break down fats for fuel because it has no insulin to allow it to use glucose.

Toxic chemicals called ketones are produced as a by-product and they make the blood acidic. Without treatment, coma and death can result.

The symptoms of diabetic ketoacidosis are:

  • excessive thirst;
  • excessive urination;
  • nausea and/or vomiting;
  • weakness and fatigue;
  • abdominal pain;
  • rapid, deep breathing;
  • breath smelling like nail polish remover or apple cider;
  • confusion; and
  • coma, eventually, if not treated.

Hyperosmolar hyperglycaemia

Hyperglycaemia may develop more slowly in people with type 2 diabetes but can still progress to dehydration, confusion, and coma — known as hyperosmolar hyperglycaemia.

Long-term complications

Persistent hyperglycaemia due to poor control of blood glucose levels can result in diabetes complications such as:

  • eye problems;
  • kidney damage;
  • heart disease; and
  • nerve damage.


Treatment of hyperglycaemia depends on the severity and the cause.

  • People with emergency complications (ketoacidosis and hyperosmolar hyperglycaemia) need urgent hospital treatment.
  • High blood sugar levels associated with an illness (see below) require treatment of the illness and perhaps a short-term adjustment of insulin dose.
  • Persistent hyperglycaemia due to poor diabetic control will need attention to diet, exercise and review of medication. If lifestyle changes are not enough, the dose or type of diabetes tablets may need changing, or an extra tablet or insulin may need to be started.

Managing blood glucose levels when you are sick

During an illness of any kind, it’s essential that people with diabetes monitor their blood glucose levels closely. Even if you are eating less than usual, or are sick with nausea and vomiting, your blood sugar levels may still be high.

You should continue to take your insulin or tablets as usual — contact your doctor or diabetes team early so that you can get help managing the situation. People with type 1 diabetes may also need to test their urine for ketones during times of illness.

When you are ill, make sure you drink plenty of water to stay well hydrated.

When to seek medical help

If your blood glucose levels don’t respond to medication, you should contact your doctor or diabetes nurse educator for advice. Obviously, if blood glucose levels continue to rise or you are very unwell or your blood glucose levels are very high you should seek medical attention immediately.

Your doctor will be able to advise you on what blood glucose levels constitute an emergency, and on what to do.