Tests
Diabetes is diagnosed by measurement of glucose in blood (or more correctly in plasma which is the fluid left behind when cells have been removed from blood) in accordance with the criteria of the Australian Diabetes Association and the World Health Organisation.
Either random or fasting measurements or the measurements made during an Oral Glucose Tolerance Test (OGTT) may be used. The OGTT involves a fasting glucose, followed by the patient drinking a standard amount of a glucose solution to "challenge" their system, followed by another glucose test two hours later.
In an individual with typical symptoms, diabetes is diagnosed by finding either a random plasma glucose concentration greater than 11.0 mmol/L or a fasting plasma glucose concentration greater than 6.5 mmol/L or a plasma glucose concentration greater than 11.0 mmol/L two hours after taking 75g of anhydrous glucose in an OGTT.
In the absence of typical symptoms, diagnosis should not be based on a single glucose determination but requires confirmation by at least one further glucose test result on another day with a value in the diabetic range. If the fasting or random glucose concentrations are do not fall into the criteria given above then an Oral Glucose Tolerance Test should be performed. Gestational diabetes (GDM) is diagnosed by OGTT, undertaken in a woman at risk for GDM.
Sometimes random urines are tested for glucose, protein, and ketones during a routine clinical examination using a 'dipstick test'. If glucose and/or protein or ketones is present on the dipped indicator strip then further investigations are necessary. This screening tool is not sensitive enough for monitoring patients who have been diagnosed as diabetic.
Diabetic patients monitor their condition by measuring their own blood glucose levels. Home blood measurements are done by placing a drop of blood (obtained by pricking the finger with a small lancet device), onto a plastic glucose test strip and then inserting the strip into a small test meter, which provides a digital readout of the blood glucose. Glucose measurements can be taken several times a day at a frequency which depends on well their blood glucose concentration is controlled.
Several laboratory tests may be used to monitor diabetes on a regular basis.
To monitor glucose control:
Glucose, Haemoglobin A1c (HbA1c)
To monitor kidney function:
Creatinine, Creatinine Clearance, Microalbumin (as Albumin Creatinine ratio {ACR} or Albumin Excretion rate)
To monitor lipids:
Triglycerides, cholesterol, HDL cholesterol, LDL cholesterol.
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