In the blood stream are the red blood cells, which are made of a molecule, haemoglobin. Glucose sticks to the haemoglobin to make a 'glycosylated haemoglobin' molecule, called haemoglobin A1C or HbA1C. The more glucose in the blood, the more haemoglobin A1C or HbA1C will be present in the blood. Red cells live for 8 -12 weeks before they are replaced. By measuring the HbA1C it can tell you how high your blood glucose has been on average over the last 8-12 weeks. A normal non-diabetic HbA1C is 3.5-5.5%. In diabetes about 6.5% is good. The HbA1C test is currently one of the best ways to check diabetes is under control; it is the blood test that gets sent to the laboratory, and it is done on the spot in some hospital clinics. Remember, the HbA1C is not the same as the glucose level. Coincidentally the glucose/HbA1C numbers for good control are rather similar though in the UK and Europe: glucose levels averaging 6.5 mmols/l before meals is equivalent to 7% HbA1C (glucose levels are higher after meals) (see below). If your diabetes is controlled (basically an HbA1C lower than 7%), every 36 months.