Blood Glucose (glu) may be elevated (HYPERglycaemia) in Diabetes Mellitus; there are different defining thresholds for diabetes depending on whether the test was taken as a random or fasting level. Low blood sugar is known as HYPOglycaemia.
Blood Glucose can be measured as a simple bedside test on a small portable device called a glucometer, using a drop of blood from a fingerprick sample. It can also be measured by the laboratory, from a venous blood sample.
Blood Glucose is often routinely requested alongside Urea & Electrolytes (U&E), as a random check on the blood sugar level. It may be specifically tested when there is a suspicion of diabetes (more correctly called diabetes mellitus). In this case, blood glucose may be tested as a random test, taken at any time of the day as convenient, or as a fasting blood glucose – usually taken first thing in the morning after an overnight fast. Symptoms of diabetes include excessive thirst leading to increased fluid intake (polydipsia), frequent urination or increased urine output (polyuria), weight loss or weight gain, or frequent infections such as thrush (candidiasis) or skin infections.
A blood glucose reading may be LOW, NORMAL, or HIGH. Low blood sugar is known as HYPOglycaemia. A high blood sugar level is not always due to diabetes, and can be due to a stress response (due to hormones such as adrenaline being active in the bloodstream), or steroid medications such as prednisolone. Blood glucose levels used to diagnose diabetes have changed over time; many doctors (including the Australian Diabetes Society) use the The World Health Organisation (WHO) criteria from 1999:
