The effects of ageing on glycation and the interpretation of glycaemic control in Type 2 diabetes

Abstract

To investigate the discrepancy in the assessment of glycaemic control using glycated haemoglobin (HbA1C) and glycated proteins (fructosamine), the effect of age on these variables was measured in non-diabetic individuals. In 232 non-diabetics, there was a linear relationship between HbA1C and age (r = 0.49, p < 0.0001). Mean HbA1C rose from 3.82% to 4.44% between the ages of 20 and 70. Consequently, when Type 2 diabetic patient samples (n = 128, median age 63 years) were classified according to European guidelines into good or poor glycaemic control using both an age-matched (n = 101) and a younger (n = 108, median age 37 years) non-diabetic reference population, fewer patients were in good control (14% vs. 25%) and more in poor control (73% vs. 53%) when the younger reference population was used (both p < 0.05). In a subgroup of 126 non-diabetic subjects, HbA1C rose with age (r = 0.48), but serum fructosamine and fasting glucose did not (r = 0.07, r = 0.009, respectively, p = NS). Age-associated differences in non-diabetic HbA1C values may affect the assessment of glycaemic control in diabetic patients. It may also partly explain discrepancies found when comparing fructosamine with HbA1C as a measure of glucose control. Age-related HbA1C reference intervals may therefore be required for the treatment of patients and the accurate auditing of clinic performance.