Diabetes is diagnosed when a person has too much glucose (sugar) in the blood. This happens because the pancreas cannot make enough insulin.
Glucose is an essential source of energy for the brain as well as a source of energy for the body. Glucose in the bloodstream comes from carbohydrate foods, which are changed into glucose after we have eaten them.
If not controlled, high blood glucose levels will eventually lead to damage to many parts of the body.
Blood-sugar levels are normally controlled by insulin. High blood glucose levels may be caused by:
- insulin deficiency – when the pancreas is not able to make enough insulin
- insulin resistance – when your body is not responding to insulin as it should.
Glucose also comes from the liver, where it has been previously stored. This ensures a constant supply even when we have not eaten recently.
For people without diabetes the level of glucose in the body is between 4 and 8 mmol/L.
Insulin is produced in the pancreas and has two jobs in the body - the first is to transport glucose from the blood supply into fat and muscle cells, where it can be used for energy. The second is to switch off the liver once the level of glucose in the blood is high enough.
Diabetes is the result of the body not creating enough insulin to keep blood glucose levels in the normal range. It cannot presently be cured, but it can be controlled, and you can lead a full and active life.
What is insulin?
Insulin is a natural hormone which helps glucose enter the body's cells where it is used for energy. If there is not enough insulin or it is not working well, glucose builds up in the bloodstream.
- When someone has diabetes, their body is not able to control their blood glucose levels and keep it in the safe range.
- If the level is too low, hypoglycaemia (low blood glucose) occurs and people feel sweaty, weak and dizzy and need to eat some glucose right away.
- If too high, hyperglycaemia (high blood glucose) can occur.
- Symptoms depend on how high or rapidly the level changes but can include excess thirst, passing excess urine, blurred vision, etc.
There are three main types of diabetes
Type 1 diabetes
People who do not make any insulin (or very little) have Type 1 diabetes. Because the immune system destroys the pancreas, they have stopped making insulin, and their body is unable to use glucose for energy. They tend to lose weight very quickly because their body is actually being starved. Their health rapidly deteriorates and they would die if insulin were not given.
They therefore require insulin by injection several times each day. Along with some dietary changes, this will allow the person to maintain good health.
Type 2 diabetes
People with Type 2 diabetes are still making insulin but the production is sluggish or their body is resistant to insulin. Becoming overweight is almost always the cause of the body becoming resistant to insulin, and can trigger Type 2 diabetes, even in young people. Type 2 diabetes can be treated with weight loss and regular physical activity. Medication in the form of tablets is often required to reduce the resistance to insulin or to stimulate the pancreas to make more insulin. Type 2 diabetes is a progressive condition in that the pancreas continues to get more sluggish over time. People with Type 2 diabetes may eventually require insulin.
Diabetes of pregnancy (gestational diabetes)
Gestational diabetes is when a pregnant woman has high levels of glucose in her blood. High blood glucose is caused because the mother cannot produce enough insulin (a pregnant woman's insulin needs are two to three times that of someone who is not pregnant). Unlike Type 1 and Type 2 diabetes, gestational diabetes is only temporary and usually disappears after pregnancy. However, a woman who has had gestational diabetes has an increased risk (50-60%) of developing Type 2 diabetes in the future, therefore they should be tested for diabetes each year.