This forms a small proportion of the total HAEMOGLOBIN in the blood. It di?ers from the major component, HbA, in that it has a glucose group attached. The rate of synthesis of HbA1c is a function of the blood-glucose concentration, and since it accumulates throughout the life span of the red blood cell – normally 120 days – the concentration of HbA1c is related to the mean blood-glucose concentration over the past 3–4 months. It is thus a useful indicator of medium-term diabetic control (see DIABETES MELLITUS) – a good target range would be a concentration of 5–8 per cent. When interpreting the HbA1c level, however, it is important to remember that wide ?uctuations in blood-glucose concentration, together with ANAEMIA or a reduced ERYTHROCYTES life span, may give misleading results.
A form of haemoglobin that is bound to the sugar glucose. In most people, 3–8 per cent of haemoglobin is glycosylated. In people with diabetes mellitus, the level of glycosylated haemoglobin may be raised if treatment has not kept the blood glucose level within the normal range. Glycosylated haemoglobin levels indicate blood glucose levels over the preceding 3 months.... glycosylated haemoglobin
(glycosylated haemoglobin) any derivative of haemoglobin in which a glucose molecule is attached to the haemoglobin molecule. The most abundant form of glycated haemoglobin is haemoglobin A1c (HbA1c), levels of which are significantly increased in diabetes. The percentage of the HbA molecules that become glycated is dependent on the general level of glucose in the plasma over the lifetime of the molecule (generally three months); this percentage is therefore used as the standard measure of the degree of control of *hyperglycaemia in a person with diabetes over this period. HbA1c values are now expressed in mmol per mol haemoglobin (mmol/mol) rather than as a percentage. The use of HbA1c as a screening tool for diabetes mellitus has become recognized.... glycated haemoglobin
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