[Etiology and physiopathology in insulin resistance and type 2 diabetes--results of twin studies].

Twin studies have provided important insights into a complicated interplay between genetic and both prenatal and postnatal environmental factors implicated in the aetiology and pathophysiology of Type 2 diabetes. Although our present knowledge is too insufficient to discard the results of classical twin studies into the relative roles of genes versus environment for the development of diabetes and its metabolic defects, it is nevertheless clear that the classical twin model has been challenged by the thrifty phenotype hypothesis and its implications of an adverse intrauterine environment for the development of diseases in man, including diabetes. However, twins with their special intrauterine conditions may represent a helpful tool in the continual search for the mechanisms, and the extent to which early environment may play a role in the development of Type 2-diabetes and its various defects of glucose homoeostasis, including insulin resistance. In addition, twin studies have proved instrumental in molecular biology studies of genotype-phenotype associations and of muscle gene expression patterns in Type 2-diabetes and/or insulin resistance.