Diabetes - Diagnosis
Four tests are typically used in the diagnosis of diabetes and
pre-diabetic states:
1-Fasting plasma glucose (FPG): Standard test for the diagnosis of
diabetes. Cheap, simple to administer and provides a measure of glycaemia for a
single point in time. A blood sample can be taken from either a vein or a
capillary. Measures the concentration of glucose in the blood after at least 8
hours of fasting.
2-Diabetes is diagnosed at fasting blood glucose of greater than or equal to
126 mg/dl plus signs / symptoms.
3-Random plasma
glucose (RPG): Any
time; measures blood glucose regardless of when the patient last ate.
4- Diabetes is diagnosed at
blood glucose of greater than or equal to 200 mg/dl
Diabetes - Diagnosis
§ Oral glucose tolerance test (OGTT): Patients must fast for eight hours before this test;
§ The patient must drink 75 g of glucose dissolved in 250-300 ml of water; Plasma glucose levels are measured immediately before and two hours after drinking the glucose solution;
§ Normal glucose tolerance is indicated when the plasma glucose returns to below 140 mg/dl 2 hours after the oral glucose load.
§ However, if the plasma glucose level is ≥140 mg/dl but <200 mg/dl, the person is said to have IGT (Impaired glucose tolerance - a state of pre-diabetes) and is at a greater risk of developing future diabetes.
Diabetes is diagnosed at 2 hour blood glucose of greater than or
equal to 200 mg/dl
Compared
with FPG, the OGTT is more expensive and more complicated to carry out. The
advantages of this test is that it is the only means of identifying people with
IGT and it is frequently needed to confirm or exclude an abnormality of glucose
tolerance in asymptomatic people.
§
§ HbA1C (Average of blood glucose over 2-3 months); A sample of blood is taken from the patient, which is then analyzed to determine the HbA1C levels. The test needs to be performed in a laboratory with the appropriate certification and standardization. It can be taken anytime, irrespective of meals.
Diabetes is diagnosed at an A1C of greater than or equal to 6.5%. Provides an indication of long-term glycaemic exposure and is a very convenient measure of long-term glucose control that is familiar to healthcare professionals and some patients. More convenient (fasting is not necessary) but more expensive, which may limit availability in some parts of the world.
§ OBESITY: Indirect methods, based on the relation between height and weight, can be used in everyday clinical practice to estimate obesity. The most common and accepted, at least in adults, measures the body mass index (BMI) and waist circumference.
People are considered obese when their BMI, a measurement
obtained by dividing a person's weight in kilograms by the square of the
person's height in metres, exceeds 30 kg/m2.
§ §
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