Pathology tests database

Sample and container requirements

EDTA Plasma

Minimum volume required

500 µL plasma

Special requirements

None

Patient preparation

Blood should be collected when patient is hypoglycaemic.

Sample viability

Turnaround time

7 days

Reference range

No associated reference range. Should be interpreted alongside with glucose and c – peptide. Non-diabetic hypoglycaemia: Evaluation of hypoglycaemia should only be undertaken for patients in whom Whipple’s triad has been documented. Firstly, review the history and physical findings to exclude more common hypoglycaemic aetiologies such as; drugs (insulin, insulin secretagogues, alcohol ingestion), critical illness (sepsis, organ failure), cortisol deficiency and non-islet cell tumours. Once these have been excluded, in the seemingly well individual, the differentials lie between accidental/ surreptitious hypoglycaemia and endogenous hyperinsulinaemia. Further evaluation is warranted and should involve the following concomitant tests in the event of an ongoing episode of hypoglycaemia; plasma glucose (for confirmation of hypoglycaemia), insulin, C-peptide, beta-hydroxybutyearate as well as the measurement of circulating oral hypoglycaemic agents (if there is a degree of suspicion). When spontaneous hypoglycaemia cannot be observed, a prolonged fast or mixed meal test may recreate the environment in which hypoglycaemia is likely to occur.

Clinical guidance

Please refer to LabTestsOnlineUK to learn more about insulin. https://labtestsonline.org.uk/tests/insulin

Notes

If glucose is above 3.1 mmol/L, insulin analysis is not usually carried out. Haemolysed samples are not suitable for analysis. Please note: Exogenous Insulin preparations have been shown to cross-react with the Architect insulin assay, but to varying degrees. The human sequence insulin preparations (Actrapid, Humulin S, Insulatard, Humulin I and Humulin M3) demonstrated similar levels of recovery (between 81 and 89%), indicating extensive cross-reactivity in the insulin assay. The insulin analogues (NovoRapid, Apidra, Humalog, Levemir and Lantus) demonstrated variable degrees of recovery with Apidra, showing the lowest recovery at 12 and 14%, while Lantus, over-recovered at 127 and 140%, demonstrating significant cross-reactivity with the assay.