Diabetes mellitus (DM) is a disease characterized by defects in action and/or secretion of insulin that results in chronic hyperglycemia and long-term severe vascular complications. The main clinical presentations with the proven genetic base are covered. Type 1 diabetes (DM1) is an autoimmune, heterogeneous, multifactorial, and polygenic-based disease. Selectively destroys 90% of beta cells of the pancreas, mediated by activated T lymphocytes in patients with haplotypes linked to major histocompatibility complex (MHC). Genetic and genomic studies have been carried out in family groups, demonstrating up to 15 affected chromosomal regions. Type 2 diabetes (DM2) presents genes with various polymorphisms which, together with post-genomic and environmental factors, make it more complex to understand the pathogenesis. Monogenic diabetes comprises neonatal diabetes (ND), maturity onset diabetes in young (MODY), an autosomal dominant transmission which is inherited directly in three successive generations, and the very rare mitochondrial diabetes. Latent autoimmune diabetes in adults (LADA) mainly affects patients with normal weight and initially diagnosed as DM2. Its characteristics are low levels of C-peptide in both fasting and post-glucagon tests. They present MHC alleles of susceptibility and positive autoantibodies: Anti-decarboxylase glutamic acid.
Part of the book: Cellular Metabolism and Related Disorders