Classification of diabetes. World Health Organization 2019. What’s new?

The review focuses on the new WHO classification published in 2019. Unlike the previous classification, this classification does not recognize subtypes of T1DM and T2DM and offers new types of diabetes: “hybrid types of diabetes” and “unclassified diabetes”. This classification provides practical guidance to clinicians for assigning a type of diabetes to individuals and choose appropriate treatment (whether or not to start treatment with insulin), particularly at the time of diagnosis. This review presents the variety of forms of diabetes, the features of their clinical picture, and also emphasizes the importance of molecular genetic and immunological studies to identify types of diabetes and determine personalized therapy. The selection of “hybrid forms” of diabetes is due to the fact that the treatment of these types of diabetes has its own characteristics associated with the specific pathogenesis of diseases. However, it is obvious that further studies should relate to the study of the mechanisms of damage and decrease in the function of в-cells. Perhaps future classification systems and, as a consequence, personalized treatment will focus on various mechanisms of damage to β-cells.