The Causes of Diabetes
- There are over 3 million people suffering from diabetes in the UK
- Diabetes is a condition in which the homeostatic control of blood glucose has failed or deteriorated
- In individuals with diabetes their insulin function is disrupted which allows the glucose concentration in the blood to rise
- The kidneys are unable to filter out this excess glucose in the blood and so it often appears in the urine
- The increased glucose concentration also causes the kidneys to produce large quantities of urine, making the individual feel thirsty due to dehydration
- There are two different types of diabetes: type I and type II
Type I diabetes
- Type 1 diabetes is a condition in which the pancreas fails to produce sufficient insulin to control blood glucose levels
- It normally begins in childhood due to an autoimmune response whereby the body’s immune system (T cells) attacks the β cells of the islets of Langerhans in the pancreas
- The β cells detect high blood sugar and synthesise insulin
- The lack of insulin also affects glycogen stores which results in an individual feeling fatigued
- If the blood glucose concentration reaches a dangerously high level after a meal then organ damage can occur
- Type 1 diabetes is normally treated with regular blood tests, insulin injections and a diabetes appropriate diet
- Health authorities encourage diabetics to eat a similar diet to the general public. They suggest five portions of fruit and veg a day, minimally processed food and consuming more polysaccharides than monosaccharides or disaccharides
- The insulin used by diabetics can be fast-acting or slow-acting; each allowing for a different level of control
- If a type I diabetic manages their condition well they can live a very full life
Type II diabetes
- Type II diabetes is more common than type I
- It usually develops in those aged 40 and over however more and more young people are developing the condition
- In type II diabetes the pancreas still produces insulin but the receptors have reduced in number or no longer respond to it
- This reduced sensitivity to insulin occurs in the liver and fat storage tissues
- The lack of response to insulin means there is a reduced glucose uptake which leads to an uncontrolled high blood glucose concentration
- This can cause the β cells to produce larger amounts of insulin which ultimately damages them
- For early-stage type II diabetes, a sugar and fat controlled diet and an exercise regime are usually sufficient treatments
- Any food that is rapidly digested into sugar will cause a sudden, dangerous spike in blood sugar
- Obesity is a major risk factor for type II diabetes; a person who is obese likely consumes a diet high in carbohydrates, and the over-production of insulin triggers the development of insulin resistance
Type I diabetes and type II diabetes
Diabetes and blood pressure
- Individuals with poorly controlled diabetes often suffer from high blood pressure
- The high blood glucose concentration lowers the water potential of the blood which causes more water to move from the tissues into the blood vessels by osmosis
- As a result, there is a larger volume of blood within the circulatory system which causes blood pressure to increase
Examiner Tip
A common exam question:Explain why the protein insulin must be administered intravenously rather than orally.Insulin is a protein, if it was taken orally it would be digested by the enzyme protease found in the gut before entering the bloodstream.