7.15 - 7.16 - Diabetes
Compare the causes of type 1 and type 2 diabetes and explain how their control addresses the underlying problem. Distinguish missing insulin from a reduced response to insulin.
7.15 - Type 1 diabetes
Normally the pancreas releases insulin when blood glucose rises. Insulin signals body cells to take up glucose and liver and muscle cells to store glucose as glycogen, lowering its concentration in blood.
In type 1 diabetes, the immune system destroys insulin-producing cells in the pancreas. The pancreas therefore produces little or no insulin. Without enough insulin signal, glucose uptake and glycogen storage are reduced, so blood glucose concentration can remain too high.
Type 1 diabetes is controlled by replacing the missing insulin, commonly using injections, an insulin pen or a pump. Blood glucose is monitored so the dose can be matched to factors such as carbohydrate intake and physical activity. Healthy food and activity support control, but they do not replace the insulin that the pancreas can no longer supply.
Insulin treatment controls blood glucose; it does not restore the destroyed pancreatic cells, so it should not be described as a cure.
7.16 - Type 2 diabetes
In type 2 diabetes, insulin may still be released, but body cells respond less strongly to it. This is insulin resistance. The reduced response means less glucose is taken up by cells and less is stored as glycogen, so glucose remains in the blood. The pancreas may also become unable to make enough insulin for the body's needs.
Type 2 diabetes is multifactorial. Excess body fat and physical inactivity can contribute to insulin resistance, while genes, age and other factors also affect risk. A person can therefore develop type 2 diabetes without having a high body mass, and a person with a high body mass does not inevitably develop it.
Control can combine several approaches:
- a controlled diet, including control of carbohydrate intake, reduces large inputs of glucose and can help manage body mass;
- physical activity increases glucose use by muscle cells in respiration, which releases energy, and can improve blood glucose control;
- loss of excess body mass can improve control for some people;
- prescribed medicines such as metformin, and sometimes insulin, can lower blood glucose by routes selected for the individual.
| Feature | Type 1 | Type 2 |
|---|---|---|
| Main physiological problem | Little or no insulin because insulin-producing pancreatic cells are destroyed by the immune system | Target cells respond poorly to insulin; insulin production may also become insufficient |
| Key term | Autoimmune destruction | Insulin resistance |
| Control | Insulin replacement with monitoring; food and activity are also managed | Diet, activity and body-mass management where appropriate; prescribed medicines and sometimes insulin |
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