The Insulin test is available in the UK but is not often used.
Here is an extract from a UK Laboratory guide for Technicians.
INSULIN TEST.
Insulin may be used, often along with glucose and C-peptide levels, to help diagnose insulinomas and to help determine the cause of hypoglycaemia (low blood glucose). Insulin and C-peptide levels also may be used to monitor the amount of insulin produced by the body (called 'endogenous' insulin), to check if the body is not responding to insulin properly (called 'insulin resistance'), and to help determine when a type 2 diabetic might need to start taking insulin injections to supplement oral medications.
Insulin levels are sometimes used in conjunction with the glucose tolerance test (GTT). Blood glucose and, sometimes, insulin levels are measured to evaluate insulin resistance, particularly in obese individuals.
Insulin levels must be evaluated in context. If fasting insulin and glucose levels are normal, most likely the body's glucose regulation system is functioning normally. If insulin is raised and glucose is normal and/or moderately raised, then there may be some insulin resistance. If the insulin is low and the glucose is high, then most likely there is insufficient insulin being produced by the body. If insulin levels are normal or raised and glucose levels are low, then the patient is hypoglycaemic due to excess insulin.
Raised insulin levels may be seen with:
1. Acromegaly
2. Cushing's syndrome
3. Drugs such as corticosteroids, levodopa, oral contraceptives
4. Fructose or galactose intolerance
5. Insulinomas
6. Obesity
7. Insulin resistance, such as appears in early type 2 diabetes
Decreased insulin levels are seen with:
1. Diabetes
2. Hypopituitarism
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Hope that helps ?
Ken.