Glucose

Glucose is an exceedingly important molecule in that it serves as the principal fuel for peripheral tissues except during prolonged fasting. The maintenance of the blood glucose concentration is closely controlled in the body and there are important disease processes which can result in its disturbance. Marked disturbance of the blood glucose concentration is life threatening.

Glucose can be measured in different sample types. However, the concentration of glucose in any sample begins to decrease immediately after collection because of the glycolytic action of red blood cells and white blood cells. For this reason, if there is likely to be any delay in sample analysis, eg a blood sample taken at a GP surgery and then transported to the main hospital laboratory, blood samples for measurement of glucose are collected into tubes containing fluoride oxalate to stop this occuring

Another thing that you need to be aware of in interpreting glucose results is that values in plasma (lab measurement of glucose) are slightly higher (a bit over 10%) than in whole blood (point of care measurement).

Interpretation of a glucose result depends on whether the patient was fasting or not. Normally a fasting plasma glucose should be between 2.5 and 6 mmol/l. Below 2.5 mmol/l is called hypoglycaemia and above 6 mmol/l is hyperglycaemia. For further details, click on the insulin molecule.

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