(e) the differences between Type 1 and Type 2 diabetes mellitus

The idea

Diabetes mellitus is a condition in which blood glucose is poorly controlled. In Type 1 diabetes, the β cells of the islets of Langerhans are destroyed (an autoimmune response), so little or no insulin is produced; it typically develops in younger people and is treated with insulin injections. In Type 2 diabetes, insulin is still produced but body cells become less responsive to it (insulin resistance), often linked to obesity and lifestyle; it typically develops later in life and is managed with diet, exercise and medication. Both types cause high blood glucose, but the underlying cause differs: Type 1 is a failure of insulin secretion, Type 2 is a failure of cell response to insulin.

What earns the marks

• Type 1 involves destruction of β cells so little or no insulin is secreted.
• Type 1 is treated with insulin injections because the body cannot produce it.
• Type 2 involves cells becoming less responsive to insulin (insulin resistance) while insulin is still produced.
• Type 2 is often associated with obesity and lifestyle and is managed by diet, exercise and medication.
• Type 1 typically develops earlier in life; Type 2 typically develops later in life.

Common mistakes and how to put them right

• Saying Type 2 diabetics produce no insulin.

  Put it right: They usually still produce insulin but cells respond poorly to it.

• Confusing the treatments: Type 1 requires insulin injections; Type 2 is usually managed first by lifestyle and medication.

• Assuming both types have the same cause.

  Put it right: Distinguish failure of insulin secretion (Type 1) from insulin resistance (Type 2).

Exam tips

• Structure the answer as paired comparisons (cause, insulin level, age of onset, treatment) rather than describing each type separately.
• Use the term insulin resistance for Type 2 and β cell destruction for Type 1.
• State clearly that both lead to high blood glucose, then explain why the causes differ.