Longitudinal Validation of Hemoglobin A1c Criteria for Diabetes Diagnosis: Risk of Retinopathy

Abstract

Receiving a diagnosis of diabetes has significant physical, emotional, and financial consequences (1). The development of precise diagnostic criteria is critical both to avoid the unnecessary burden of treatment in individuals who do not have the disease and to promptly identify individuals who are at risk for developing complications from diabetes so they can be appropriately counseled on disease management. Traditionally, the diagnosis of diabetes was based on glucose levels associated with the progression to overt, symptomatic disease. In 1997, the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus refocused the basis of the diagnosis to the relationship between glucose levels and the presence of long-term complications (2). This recommendation was based on the available epidemiological literature demonstrating the association between various glucose measures and microvascular complications of diabetes—particularly retinopathy, which tends to have a stronger correlation to glycemia (2–4). These studies were mainly cross-sectional, although one study did examine microvascular complications longitudinally (4). Most recently, an international expert committee and the American Diabetes Association further specified that diabetes should be diagnosed if hemoglobin A1c is ≥6.5% (5,6). This was based in part on additional studies showing a …