Insulin in Blood Sugar Control (OCR Gateway GCSE Biology: Combined Science)

• Regulation of blood glucose is an example of homeostasis
• The concentration of glucose in the blood must be kept within a narrow range 
  • Excessively high levels of glucose in the blood can lead to cells of the body losing water by osmosis, which can be dangerous
  • Excessively low levels of glucose in the blood can lead to the brain receiving insufficient glucose for respiration, potentially leading to a coma or even death
• Blood glucose levels are regulated by the pancreas and the liver using hormones insulin and glucagon
  • Insulin stimulates cells to take in glucose from the bloodstream (particularly liver and muscle cells)
  • In liver and muscle cells excess glucose is converted into glycogen (a polymer of glucose) for storage

Type 1 diabetes

• Type 1 diabetes is a disorder in which the pancreas fails to produce sufficient insulin to control blood glucose levels
• Scientists think this is a result of a person’s own immune system destroying the cells of the pancreas that make insulin during development
• Type 1 diabetes is characterised by uncontrolled high blood glucose levels and is normally treated with insulin injections

Type 2 diabetes

• In Type 2 diabetes the body cells no longer respond to insulin produced by the pancreas - the person still makes insulin but their cells are resistant to it and don’t respond as well as they should
• This can also lead to uncontrolled high blood glucose levels
• Obesity is a big risk factor for Type 2 diabetes; probably because a person who is obese may consume a diet high in carbohydrates, and over-production of insulin results in resistance to it developing
• A carbohydrate-controlled diet and an exercise regime are common treatments for Type 2 diabetes

Table to compare type 1 and type 2 diabetes