Age does not influence levels of HbA(1c) in normal subject

To resolve whether haemoglobin A(1c)(HbA(1c)) levels in normal subjects inc rease with age, we measured HbA(1c) in 399 patients undergoing routine oral glucose tolerance test (OGTT). The OGTT results categorized the patients i nto 127 normal, 94 impaired glucose tolerance (IGT) and 178 diabetic. None of these groups showed a significant correlation between HbA(1c) and age an d we cannot, therefore, see a need for age-specific reference ranges for Hb A(1c). Some of the confusion in the literature may have arisen from less ri gorous categorization of subjects than we used, resulting in the inclusion of some individuals with IGT or diabetes in the 'normal' groups of other st udies. The prevalence of such abnormality would be expected to be greater a mongst older subjects, falsely suggesting a correlation between HbA(1c) and age, and we were able to demonstrate this with our own data when insuffici ently rigorous criteria were applied for the selection of normal subjects.