Abstract
The use of glycosylated haemoglobin measurement for monitoring the long-term glycaemic control of diabetic patients is now well established. To enable this material to be measured routinely at the Royal Sussex County Hospital, a method based on affinity chromatography using an m-aminophenylboronate agarose was developed. This technique provides a simple, reproducible assay, which is inexpensive and allows the assay of upto 60 samples per day. A "between-batch" CV of 2% was achieved. Affinity chromatography was also used for the separation of glycosylated plasma proteins with a "between-batch" CV of 5%. Measurement of the protein content in the fractions collected from the gel was performed by the Coomassie Brilliant Blue method of Bradford. In this way both glycosylated haemoglobin and glycosylated plasma proteins could be measured in the same sample and their individual usefulness in any clinical situation assessed. Investigation of patients admitted to hospital after a period of poor glycaemic control confirmed that glycosylated plasma proteins with their shorter half-life, decreased at a far quicker rate following the onset of treatment, than did glycosylated haemoglobins. Part of the clinical work showed that both glycosylated haemoglobins and glycosylated plasma proteins could be used to detect glucose intolerance, although glycosylated haemoglobin measurement proved more useful as a screening test for diabetes mellitus possibly due to its better precision. A two-year study of 35 pregnant diabetic patients established that both glycosylated haemoglobin and glycosylated plasma proteins measured in the third trimester of pregnancy could be used with a high frequency (73.5% and 68.8%, respecitvely) to correctly predict macrosomia, and with a higher frequency (85.3% and 84.4%) to predict problems at delivery. Investigation of both measurements in association with miscarriages to diabetic patients showed abnormal glycosylated plasma protein results in 3 cases. No correlation was found between birth weight ratios and glycosylated material in cord blood. A two-year study of diabetic patients attending an out-patient clinic showed that their overall control, in terms of glycosylated haemoglobin measurement, improved significantly during the period of study. Initial investigations to establish exactly what the affinity gel separates for both the glycosylated haemoglobin and glycosylated plasma protein assay are described.