Autoantibodies to GAD65 and IA-2 antibodies are increased, but not tissue transglutaminase (TTG-Ab) in type 2 diabetes mellitus (T2DM) patients from South India

Genetics of type 2 diabetes mellitus and other specific types of diabetes; its role in treatment modalities

Type 2 diabetes mellitus (T2DM) is among the most challenging health issues of the 21st century and is associated with an alarming rise in the incidence. The pathophysiological processes that lead to development of T2DM are still unclear, however impairment in insulin secretion and/or action is clearly indicated. Type 2 diabetes is a polygenic disorder with multiple genes located on different chromosomes contributing to its susceptibility. Analysis of the genetic factors is further complicated by the fact that numerous environmental factors interact with genes to produce the disorder. Only a minority of cases of type 2 diabetes are caused by single gene defects and one example is maturity onset diabetes of the young (MODY). Previous studies indicated that variants in genes encoding the pancreatic β-cell K+ATP channel subunits Kir6.2 (KCNJ11) and SUR1 (ABCC8) are associated with neonatal diabetes. Six different types of maturity onset diabetes of young (MODY) have been identified based on characteristic gene defect. The common Pro12Ala polymorphism in peroxisome proliferator-activated receptor-γ (PPAR-γ) gene was confirmed in several studies to be associated with type 2 diabetes as well. More recently, studies reported variants within a novel gene, TCF7L2, as a putative susceptibility gene for type 2 diabetes across many ethnic backgrounds around the world. MODY patients respond better to sulphonylureas and metformin, while neonatal diabetes patients with genetic mutations can be changed from insulin to oral drugs. We hereby provide a comprehensive review on the role of genetics in type 2 diabetes mellitus.

Latent autoimmune diabetes in adults: A distinct but heterogeneous clinical entity

Latent autoimmune diabetes in adults (LADA) accounts for 2%-12% of all cases of diabetes. Patients are typically diagnosed after 35 years of age and are often misdiagnosed as type II Diabetes Mellitus (DM). Glycemic control is initially achieved with sulfonylureas but patients eventually become insulin dependent more rapidly than with type II DM patients. Although they have a type II DM phenotype, patients have circulating beta (β) cell autoantibodies, a hallmark of type I DM. Alternative terms that have been used to describe this condition include type 1.5 diabetes, latent type I diabetes, slowly progressive Insulin Dependent Diabetes Mellitus, or youth onset diabetes of maturity. With regards to its autoimmune basis and rapid requirement for insulin, it has been suggested that LADA is a slowly progressive form of type I DM. However, recent work has revealed genetic and immunological differences between LADA and type I DM. The heterogeneity of LADA has also led to the proposal of criteria for its diagnosis by the Immunology of Diabetes Society. Although many workers have advocated a clinically oriented approach for screening of LADA, there are no universally accepted criteria for autoantibody testing in adult onset diabetes. Following recent advances in immunomodulatory therapies in type I DM, the same strategy is being explored in LADA. This review deals with the contribution of the genetic, immunological and metabolic components involved in the pathophysiology of LADA and recent approaches in screening of this distinct but heterogeneous clinical entity.