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

Objective-To see whether two measures of glycated haemoglobin concentration-the haemoglobin A(1) (HbA(1)) value and the haemoglobin A1c (HbA(1c) value-assess blood glucose control differently in diabetes. Design-Diabetic patients had glycaemic control assessed on the basis of HbA(1) and HbA(1c) values measured by the same high performance liquid chromatography instrument and on the basis of HbA(1) measured by electrophoresis. 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 assessed by the HbA(1c) value compared with both HbA(1) assays (39 (19%) and 130 (63%) respectively when using highperformance liquid chromatography; 63 (30%) acid 74 (36%) when using electrophoresis). The median patient 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 chromatography method, and 4.1 when using HbA(1) measured by electrophoresis. Conclusions-Large differences exist between HbA(1) and HbA(1c) in the classification of glycaemic control in diabetic patients. The HbA(1c) value may suggest a patient is at a high risk of long term diabetic complications when the HbA(1) value may not. Better standardisation of glycated haemoglobin measurements is advisable.