Home – Our services – Pathology – Pathology tests – Glucose

Glucose

Background

Glucose is stored in the body in the form of glycogen. Under hormonal control, glucose from either the diet or the body stores is mobilised and used as an energy source. The two hormones that are principally involved in glucose metabolism are insulin and glucagon. After feeding, the glucose levels in the blood increase, but then return to normal as insulin, secreted by the beta cells of the Islets of Langerhans in the pancreas, increase peripheral glucose utilisation and storage.

Glucagon is secreted by the alpha cells of the Islets of Langerhans in the pancreas in response to low glucose levels e.g during fasting. This homeostatic mechanism maintains the plasma glucose within relatively narrow limits. The main disease of this endocrine system is diabetes mellitus (DM), when either insulin is not secreted (Type I) or is secreted normally but the tissues are not respondent (Type II).

Random glucose estimations may be of value in the long-term control of a patient, but for diagnostic purposes a fasting glucose is of more use. It is sometimes necessary in the milder forms of the disease to perform a glucose tolerance test (GTT), in which the glucose levels are followed after ingestion of a standard dose of glucose.

Reference ranges

Serum/plasma
Fasting: 2.2 – 6.0 mmol/L
Random: 2.5 – 11.0 mmol/L
Urine:
Less than 2.78 mmol/24hours
CSF:
Doctor will interpret CSF glucose level alongside serum/plasma glucose level.

Specimen requirements

Sample type

  • Serum, Lithium Heparin Plasma, Fluoride Oxalate Plasma, Urine, CSF.
    • However it is important that Serum/Lithium Heparin Plasma is separated from its cellular components as soon as possible after collection.
    • Blood taken into a Fluoride Oxalate Tube is the specimen of choice for GP surgeries, where there may be a delay in transportation to the lab.
    • Fluoride inhibits glycolysis and so the glucose is stable for 24 hours in this container.

Sample identification:

  • Three patient identifiers from
    • Name
    • D.O.B.
    • Address
    • N.H.S. number
    • Unit Number
    should match on the specimen and request form. This check may be performed prior to centrifugation by the Central Sort department.

Turnaround time

2 hours