Control of blood glucose concentration: Type 1 diabetes is a disorder in which the pancreas fails to produce sufficient insulin. It is characterised by uncontrolled high blood glucose levels and is normally treated with insulin injections.

The idea

Type 1 diabetes is a disorder of blood glucose control. The pancreas fails to produce sufficient insulin, so glucose is not removed from the blood efficiently after meals. Blood glucose can remain high, a state called hyperglycaemia, and glucose may appear in the urine. Typical effects include thirst, frequent urination, tiredness and weight loss. These have different causes: thirst and frequent urination follow from glucose and water loss in urine, whereas weight loss occurs mainly because cells cannot use glucose, so the body breaks down fat and protein for energy. Because the body cannot make enough insulin, the usual treatment is insulin injections, often several times a day, alongside monitoring blood glucose and managing diet and exercise. Injecting insulin replaces the missing hormone so that cells take up glucose and store it as glycogen.

What earns the marks

• In type 1 diabetes the pancreas fails to produce sufficient insulin, so blood glucose is not regulated effectively.
• Uncontrolled high blood glucose levels are a characteristic feature and can be detected by monitoring blood or urine.
• Thirst and frequent urination are linked to glucose remaining in the blood and being excreted in urine, which draws water out with it.
• Weight loss in type 1 diabetes occurs mainly because cells cannot use glucose for energy, so the body breaks down fat and protein instead.
• Insulin injections are the normal treatment because they replace the insulin the pancreas cannot produce.
• Injected insulin allows cells to take up glucose and store it as glycogen, lowering blood glucose.
• Management also involves monitoring blood glucose concentration and adjusting diet and exercise, but insulin injection is the defining treatment.

Common mistakes and how to put them right

• Confusing type 1 and type 2 diabetes.

  Put it right: Type 1 involves insufficient insulin production by the pancreas, whereas type 2 involves cells becoming less responsive to insulin.

• Stating that type 1 diabetes is treated with diet alone.

  Put it right: Diet and exercise help management, but insulin injections are normally required.

• Attributing weight loss to glucose being excreted in urine.

  Put it right: Weight loss is mainly due to fat and protein breakdown when cells cannot use glucose for energy.

• Writing that insulin injections cure diabetes.

  Put it right: They treat and control the condition but do not restore the pancreas's ability to produce insulin.

Exam tips

• Link each feature of the disorder to its cause: insufficient insulin leads to high blood glucose, which leads to the symptoms.
• Use the phrase 'uncontrolled high blood glucose levels' when describing the characteristic state, and avoid saying simply 'too much sugar in the blood' without qualification.
• When asked about treatment, state that insulin is injected because it is a protein hormone and would be digested if swallowed.