Current diagnostic criteria and their impact on outcome and management

The 1997 American Diabetes Association (ADA) Expert Committee on the Diagnosis and Classification of Diabetes Mellitus and the Provisional Report of the WHO Consultation focus on a fasting plasma glucose (FPG) that is 126 mg/dl or greater and confirmed on a subsequent day as the preferred criterion for the diagnosis of diabetes mellitus. This criterion is supported by studies demonstrating that this threshold accurately differentiates between non-diabetic and diabetic populations and is associated with the development of specific diabetic microvascular complications. It corrects for the inequivalence of the FPG and 2- hour post glucose (2hPG) criteria of the previous National Diabetes Data Group (NDDG) and WHO diagnostic schemes and recognises that oral glucose tolerance tests (OGTTs) rarely are performed in clinical practice. Although the new and the previous criteria produce similar estimates of the prevalence of diabetes, there may be a considerable degree of reclassification. Preliminary studies suggest that the new criteria favour the diagnosis of diabetes in younger and more obese individuals, whereas the older criteria increase the likelihood of diagnosis in older, leaner individuals.