Should There be Concern About Autoimmune Diabetes in Adults? Current Evidence and Controversies

Autoimmune diabetes has a heterogeneous phenotype. Although often considered a condition starting in childhood, a substantial proportion of type 1 diabetes presents in adult life. This holds important implications for our understanding of the factors that modify the rate of progression through the disease prodrome to clinical diabetes and for our management of the disease. When autoimmune diabetes develops in adulthood, insulin treatment is often not required at the time of diagnosis, and this autoimmune non-insulin requiring diabetes is generally termed latent autoimmune diabetes in adults (LADA). Patients with LADA are generally leaner, younger at diabetes onset; have a greater reduction in C-peptide; and have a greater likelihood of insulin treatment as compared with patients with type 2 diabetes. The LADA subset of patients with adult-onset autoimmune diabetes has highlighted many shortcomings in the classification of diabetes and invokes the case for more personalized data analysis in line with the move towards precision medicine. Perhaps most importantly, the issues highlight our persistent failure to engage with the heterogeneity within the most common form of autoimmune diabetes, that is adult-onset type 1 diabetes, both insulin-dependent and initially non-insulin requiring (LADA). This review discusses characteristics of autoimmune diabetes and specifically aims to illustrate the heterogeneity of the disease.