Evaluation of glycaemia for preceded period of time: glycated proteins - glycated haemoglobin HbA1; HbA1c and fructosamine: common data for the parameters, indications for investigation, patient preparation, specimen, reference ranges, informative content and results interpretation.
HbA1c Glucose Test - The glycosylated haemoglobin - glycohemoglobin also called the HbA1c, is A small fraction of HbA becomes modified during its lifetime (HbA1). HbA1c is formed when glucose molecules attach to HbA molecules in a process known as glycosylation. Glycosylation reactions are common and occur naturally in the body. The process by which HbA1c is formed, however, occurs in the absence of enzymes and is therefore referred to as non-enzymatic glycosylation, or simply 'glycation'. HbA1c should not be used for diagnosis in pregnant women, people who have had recent severe bleeding or blood transfusions, those with chronic kidney or liver disease, and people with blood disorders such as iron-deficiency anaemia, vitamin B12 anaemia, and haemoglobin variants.
indications for investigation: Used to monitor the long-term response to diabetes therapy - whether treatment includes oral hypoglycaemics or insulin or a combination. The test reflects the average blood sugar level for the previous two to three months.
Patient Preparation for the test has not restrictions on foods, fluids or medications.
Specimen: venous blood with anticoagulant EDTA. The HbA1c test measures the percentage of haemoglobin molecules in the red blood cells that have glucose attached.
Reference ranges: HbA1c of 6% or less is normal.
Results interpretation: If HbA1c is above 7%, it means that the diabetes control may not be as good as it should be.
- >6.5% = diabetes
- <6.0% = not diabetic
- in between 6.0-6.5 may be this is 'pre-diabetes' or 'at risk of diabetes'.
Fructosamine is a compound that can be considered the result of non-enzymatic reaction between glucose and amine from serum proteins such as albumin and are known also as glycated serum protein. Glycated protein determines the average glucose over the past 2-3 weeks.
indications for investigation: useful in situations where the HbA1c cannot be reliably measured. Instances where fructosamine may be a better monitoring choice than A1C include:
- i. Rapid changes in diabetes treatment
- ii. Diabetic pregnancy
- iii. RBC loss or abnormalities
Specimen: serum Reference ranges: 285 μmol/l, mean 240 μmol/l. Compensated diabetes up to 350 μmol/l, decompensated over 350 μmol/l.