Diagnostic Value of HbA1c for Type 2 Diabetes

Diagnostic Value of HbA1c for Type 2 Diabetes: A1c test was investigated for its use as screening parameter for diabetes in a cohort at increased risk for the disease. The oral glucose tolerance test classified 1,523 individuals as normal glucose tolerant (NGT), 387 as impaired glucose tolerant (IGT) or having impaired fasting glycemia (IFG) and 126 as diabetic. The 6.5% cut-off value of HbA1c classified 47% of the diabetic individuals correctly. Of the remaining 53% diabetic individuals (HbA1c <6.5%) 35% had increased fasting glucose levels, while 65% were only diagnosed by their increased 2 h glucose values. From the results, it was concluded that a cut-off value of 6.5% HbA1c classifies diabetic subjects with a specificity of 98.7%. However, the sensitivity of 46.8% is low, indicating that more than half of diabetic subjects are missed when using this test. The data shows that the use of HbA1c as the primary diagnostic test will reduce diabetes prevalence. Results suggest that HbA1c and OGTT measurements cannot simply be exchanged, but most probably detect and define different categories of diabetes, i. e., categories with different risk of cardiovascular disease. Exp Clin Endocrinol Diabetes: DOI: 10.1055/s-0030-1270440