AQA · A-Level · Biology
Course version: 7402 · Version from Sept 2016
The causes of types I and II diabetes and their control by insulin and/or…
Full specification wording
Control of blood glucose concentration (A-level only): The causes of types I and II diabetes and their control by insulin and/or manipulation of the diet.
In type I diabetes the beta cells of the islets of Langerhans are destroyed, usually by an autoimmune response, so little or no insulin is produced.
Checked against the AQA 7402 specification (opens in a new tab) on .
- Point 7 of 9
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
In type I diabetes the beta cells of the islets of Langerhans are destroyed, usually by an autoimmune response, so little or no insulin is produced. It usually begins in childhood, develops quickly, and is controlled by injecting insulin matched to diet and exercise. Insulin must be injected rather than swallowed because it is a protein and would be hydrolysed by proteases in the gut. In type II diabetes insulin is still produced and released, but target cells respond poorly because their receptors are fewer, faulty or less sensitive, which is insulin resistance; the pancreatic cells are not destroyed. Type II develops gradually and is associated with obesity, a diet high in fat and sugar, inactivity, age and family history. It is controlled first by manipulating the diet, losing weight and exercising, with drugs and sometimes insulin added later.
What earns the marks
- Type I caused by destruction of the beta cells of the islets of Langerhans, so little or no insulin is produced.
- People with type II diabetes still produce and release insulin, but target cells are less responsive or less sensitive to it.
- Type I controlled by insulin injections matched to diet and exercise; insulin is injected because it would be digested by proteases if swallowed.
- Type II controlled by manipulation of the diet, weight loss and exercise, with drugs or insulin added later if needed.
- Obesity and a diet high in fat and sugar identified as risk factors for type II diabetes, using the term risk factor rather than cause.
- Autoimmune destruction of beta cells described as the cause of type I diabetes.
Common mistakes and how to put them right
Saying people with type II diabetes produce no insulin.
Put it right: They still produce insulin, but target cells respond poorly to it.
Claiming the pancreatic cells are destroyed in type II diabetes.
Put it right: Beta cell destruction occurs in type I; type II involves insulin resistance.
Writing that type I diabetes can be controlled by diet alone.
Put it right: Type I requires insulin injections; diet and exercise are matched to the insulin dose.
Treating a correlation between obesity and type II diabetes as proof that obesity causes it.
Put it right: Obesity is a risk factor; correlation does not establish causation.
Forgetting to explain why insulin cannot be taken as a tablet.
Put it right: Insulin is a protein and would be hydrolysed by proteases in the digestive system.
Exam tips
- Set the answer out as a contrast, giving cause, age of onset and treatment for each type in turn.
- Use the term risk factor rather than cause when discussing obesity and diet.
- When evaluating data, comment on the species studied, sample size and duration of the study before drawing conclusions.
Try the lesson
The start of the Control of blood glucose concentration (A-level only): The causes of types I and II diabetes and their control by insulin and/or manipulation of the diet. lesson, made from checked teaching notes for this specification point.
Have a go first
Which statement describes the underlying cause of type I diabetes?
Listen
In type I diabetes the beta cells of the islets of Langerhans are destroyed, usually by an autoimmune response, so little or no insulin is produced. It usually begins in childhood, develops quickly, and is controlled by injecting insulin matched to diet and exercise. Insulin must be injected rather than swallowed because it is a protein and would be hydrolysed by proteases in the gut. In type II diabetes insulin is still produced and released, but target cells respond poorly because their receptors are fewer, faulty or less sensitive, which is insulin resistance; the pancreatic cells are not destroyed. Type II develops gradually and is associated with obesity, a diet high in fat and sugar, inactivity, age and family history. It is controlled first by manipulating the diet, losing weight and exercising, with drugs and sometimes insulin added later. A strong answer earns marks for these points. Type I caused by destruction of the beta cells of the islets of Langerhans, so little or no insulin is produced. People with type II diabetes still produce and release insulin, but target cells are less responsive or less sensitive to it. Type I controlled by insulin injections matched to diet and exercise; insulin is injected because it would be digested by proteases if swallowed. Type II controlled by manipulation of the diet, weight loss and exercise, with drugs or insulin added later if needed. A common slip: Saying people with type II diabetes produce no insulin. Instead, they still produce insulin, but target cells respond poorly to it. Exam tip: Set the answer out as a contrast, giving cause, age of onset and treatment for each type in turn.
Key words
Say what each word means before you turn the card.
Beta cell destruction and autoimmune cause
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Insulin resistance and receptor sensitivity
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Insulin injection versus oral administration
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Diet, weight control and exercise
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See every definition
- Beta cell destruction and autoimmune cause
- The beta cells of the islets of Langerhans are destroyed, usually by an autoimmune response, so little or no insulin is produced.
- Insulin resistance and receptor sensitivity
- Insulin is still produced and released, but target cells respond poorly because their receptors are fewer, faulty or less sensitive.
- Insulin injection versus oral administration
- Insulin must be injected rather than swallowed because it is a protein and would be hydrolysed by proteases in the gut.
- Diet, weight control and exercise
- Controlled first by manipulating the diet, losing weight and exercising, with drugs and sometimes insulin added later.
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