Differences in Rates of Glycation (Glycation Index) May Significantly Affect Individual Hba 1c Results in Type 1 Diabetes

Ten type 1 diabetic patients recorded their daily home blood glucose values, pre- and post-prandially, for 12 weeks. Blood was collected weekly for HbA_1c and total haemoglobin measurement. A rolling 28-day mean of all blood glucose values and a glycation index (the ratio of the HbA_1c to the rolling mean blood glucose) were calculated. In the pooled patients' data, there was a large scatter of results about the HbA_1c versus mean blood glucose regression line. There was less variation in the results of individual patients. The glycation indices showed marked inter-individual variation, and in 60% of patients there was an inverse relationship between glycation index and mean blood glucose, suggesting a non-linear relationship between mean blood glucose and HbA_1c. Patients should be monitored on the basis of their own previous results, and in some patients blood HbA_1c may be a less sensitive index of mean blood glucose concentration at higher glucose levels.