(High Blood Sugar · Hyperglycemia)

In this condition factsheet:

• The facts on Diabetes


• Causes of Diabetes


• Symptoms and Complications of Diabetes


• Diagnosing Diabetes


• Treating and Preventing Diabetes

The Facts on Diabetes

Diabetes is a condition where people don't produce enough insulin to meet their body's needs and/or their cells don't respond properly to insulin. Insulin is important because it moves glucose, a simple sugar, into the body's cells from the blood. It also has a number of other effects on metabolism.

The food that people eat provides the body with glucose, which is used by the cells as a source of energy. If insulin isn't available or doesn't work correctly to move glucose from the blood into cells, glucose will stay in the blood. High blood glucose levels are toxic, and cells that don't get glucose are lacking the fuel they need to function properly.

There are two main kinds of diabetes: type 1 diabetes and type 2 diabetes. More than 90% of all people with diabetes have type 2. Overall, more than 3 million Canadians have diabetes, and the number is rapidly rising. Over a third of people with type 2 diabetes are unaware they have the disease and are not receiving the required treatment because, for many people, early symptoms are not noticeable without testing.

Type 1 diabetes occurs when the pancreas cannot make insulin. Everyone with type 1 diabetes requires insulin injections. Most people are diagnosed with type 1 diabetes during their childhood or adolescent years. Type 1 diabetes occurs most commonly in people of northern European ancestry.

Type 2 diabetes occurs when the pancreas does not make enough insulin or the body does not use insulin properly. It usually occurs in adults, although in some cases children may be affected. People with type 2 diabetes usually have a family history of this condition and 90% have an unhealthy body weight. People with type 2 diabetes may eventually need insulin injections. This condition occurs most commonly in people of Indigenous and African descent, Hispanics, and Asians.

Another less common form is gestational diabetes, a temporary condition that occurs during pregnancy. Depending on risk factors, between 3% to 20% of Canadian women will develop gestational diabetes which can be harmful for the baby if not controlled. The problem usually clears up after delivery, but women who have had gestational diabetes have a higher risk of developing type 2 diabetes later in life.

Prediabetes is a term used to describe blood sugar levels that are higher than normal, but not high enough to be classified as diabetes. Many people with prediabetes go on to develop diabetes.

Causes of Diabetes

Type 1 diabetes is an autoimmune disorder. It's believed that a combination of genetic predisposition and additional environmental (as yet unidentified) factors provoke the immune system into attacking and killing the insulin-producing cells in the pancreas. It can develop at any age, but is most commonly diagnosed in childhood or adolescence.

Type 2 diabetes is mainly caused by insulin resistance. This means no matter how much or how little insulin is made, the body can't use it as well as it should. As a result, glucose can't be moved from the blood into cells. Over time, the excess sugar in the blood gradually poisons the pancreas causing it to make less insulin and making it even more difficult to keep blood glucose under control.

Obesity is a leading cause of insulin resistance – about 90% of people with type 2 diabetes have an unhealthy body weight. Genetic factors are also likely to be involved in the cause of type 2 diabetes. A family history of the disease has been shown to increase the chances of getting it.

Other risk factors for the development of type 2 diabetes include:

• being 40 years of age or older
• being of Indigenous, Hispanic, South Asian, Asian, or African descent
• blood vessel disease (e.g., damage to blood vessels in eyes, kidneys, nerves, heart, brain, or arms and legs)
• high blood pressure
• high cholesterol
• a history of gestational diabetes
• a history of prediabetes or impaired fasting glucose
• giving birth to a large baby
• certain medical conditions (e.g., HIV infection)
• mental health disorders (e.g., bipolar disorder, depression, schizophrenia)
• acanthosis nigricans (a condition causing darkened patches of skin)
• polycystic ovary syndrome
• obstructive sleep apnea
• use of certain medications (e.g., corticosteroids such as prednisone, certain antipsychotic medications, certain antiviral medications for HIV)

Symptoms and Complications of Diabetes

People with type 1 diabetes who are not being treated urinate frequently and feel excessively thirsty. They usually feel very tired and experience severe weight loss despite normal or excessive food intake.

The symptoms of type 2 diabetes usually appear more gradually. People with type 2 diabetes who do not have their blood glucose under control often have a persistent, mild thirst. They urinate frequently, and often feel mild fatigue and complain of blurred vision. Many women with the disease have recurring vaginal yeast infections.

Diabetes is a major cause of heart disease, one of the leading causes of death in Canada. It's also the biggest cause of blindness and kidney failure in Canadian adults. Older adults with diabetes are twice as likely to develop high blood pressure as people without diabetes.

People with diabetes are 20 times more likely to undergo foot and other "lower extremity" amputations due to circulatory problems. Between 34% to 45% of men who have diabetes will experience erectile dysfunction at some point.