Insulin, produced by pancreatic beta cells, regulates glucose uptake and utilization and is involved in protein synthesis and triglyceride storage. It is often measured alongside C-peptide.

Clinical uses of insulin measurements:

1. Evaluation of possible insulinoma: In cases of hypoglycaemia, diagnosis of insulinoma relies on proving inappropriate secretion of insulin during a hypoglycaemic episode.

2. Hypoglycaemia of infancy due to hyperinsulinaemia.

3. Diagnosis of factitious hypoglycaemia together with measurement of C-peptide.

4. Discrimination of type 1 and type 2 diabetes mellitus: Insulin and C-peptide concentrations are generally low in patients with type 1 diabetes mellitus, and either normal or elevated in early type 2 diabetes, and decreased in later stages.

Sample Requirements and Reference Ranges