Classification and Diagnosis of Diabetes Mellitus

Diabetes is a major contributor to the global disease burden. The first official recommendation on the diagnostic criteria and classification of diabetes was published in 1965. At the time measurement of 2-hour plasma glucose during an oral glucose tolerance test was the only recommended diagnostic test. Today, measures of fasting plasma glucose and glycated haemoglobin are recognized alternatives. Diagnostic criteria for diabetes are universally agreed but criteria for intermediate hyperglycaemia differ. Classification of diabetes has evolved with improved understanding of the aetiopathology of diabetes but remains challenging due to the overlap of diabetes phenotypes. While new classification systems have been proposed to address the limitations of the current system, lack of global access to diagnostic tests which might better characterize types of diabetes hinders their universal application.