GLYCATED HEMOGLOBIN VALUES - PROBLEMS IN ASSESSING BLOOD-GLUCOSE CONTROL IN DIABETES-MELLITUS

Objective-To see whether two measures of glycated haemoglobin concentr ation-the haemoglobin A(1) (HbA(1)) value and the haemoglobin A1c (HbA (1c) value-assess blood glucose control differently in diabetes. Desig n-Diabetic patients had glycaemic control assessed on the basis of HbA (1) and HbA(1c) values measured by the same high performance liquid ch romatography instrument and on the basis of HbA(1) measured by electro phoresis. Setting-A diabetic outpatient clinic. Subjects-208 diabetic patients and 106 nondiabetic controls. Main outcome measures-Glycated haemoglobin concentrations classified according to European guidelines as representing good, borderline, or poor glycaemic control by using standard deviations from a reference mean. Results-Fewer patients were in good control (25;12%) and more poorly controlled (157;75%) as asse ssed by the HbA(1c) value compared with both HbA(1) assays (39 (19%) a nd 130 (63%) respectively when using highperformance liquid chromatogr aphy; 63 (30%) acid 74 (36%) when using electrophoresis). The median p atient value was 8.0 SD from the reference mean when using HbA(1c), 5. 9 when using HbA(1) measured by the same high performance liquid chrom atography method, and 4.1 when using HbA(1) measured by electrophoresi s. Conclusions-Large differences exist between HbA(1) and HbA(1c) in t he classification of glycaemic control in diabetic patients. The HbA(1 c) value may suggest a patient is at a high risk of long term diabetic complications when the HbA(1) value may not. Better standardisation o f glycated haemoglobin measurements is advisable.