Semiautomated determination of glycated albumin in glycaemic control of diabetic patients

Abstract

Assessment of blood glucose concentration is essential in the control of diabetes mellitus. The measurement of glycated haemoglobin @IbAr,) is widely used for the estimation of long-term (6-10 weeks) glycaemic control (1). Fructosamine determination as an estimation of glycated plasma proteins has been proposed as an alternative to HbA1, in shorterterm control of diabetes because some of the major drawbacks of HhA,, determination, such as the altered values of HbAr, in patients with anaemia or haemoglobinopathies, would be circumvented (2). However, different studies have shown that the usefulness of the fructosamine determination is very limited because of the influence of serum albumin (31, immunoglobulins (41, and bilirubin (5) on its measurement. An alternative approach involves the determination of glycated albumin (GAb). Albumin is the most abundant of the circulating plasma proteins and, having a half-life of about 19 days as compared to the 90-120 day half-life of the average erythrocyte, would more readily reflect the fluctuations in glycaemic control. GAb accounts for about 80% of the glycated plasma proteins and is known to increase in patients with poorly controlled diabetes (6). Several techniques have been described to measure GAb in human serum (6-8). In the present study we evaluate a semiautomated commercial method using a boronic acid resin affinity-column chromatography to separate glycated and nonglycated albumin followed by a new immunoturbidimetric assay of the chromatographed fractions in a Monarch 2000 automated analyser. Results are compared to those of HbAI, using the same chromatographic system and a calorimetric detection.