Non-enzymatically glycosylated serum protein in diabetes mellitus: an index of short-term glycaemia.

We measured non-enzymatically-glycosylated serum protein by a colorimetric assay in 107 diabetic and 82 control subjects. The mean level in diabetics was more than twice that in controls. Cross sectional and longitudinal studies in diabetic patients showed that glycosylated serum protein levels correlated with both fasting serum glucose and glycosylated haemoglobin levels. The correlation between glycosylated serum protein and fasting serum glucose was closer in Type 2 than in Type 1 diabetes. Treatment aimed at improving control in eight poorly controlled diabetic patients resulted in a 37% mean fall in glycosylated serum protein within one week, whereas glycosylated haemoglobin decreased only 8%. These studies confirm that non-enzymatic glycosylation of serum proteins is enhanced in diabetes. Measurement of glycosylated serum protein appears to provide an index of glycaemia over the preceding several days. It has the advantage of detecting improvements in glycaemic control much sooner than does glycosylated haemoglobin measurement.