Diabetes Mellitus is the most common chronic disease in childhood, second only to asthma. Diabetes in children is generally insulin dependent and fits the type 1 category (T1DM, IDDM). (Franzesea et al, 2004). In fact, at variance with adults, IDDM represents 80–85% of all cases of diabetes in childhood and adolescence. However, this percentage is susceptible to change since other forms of diabetes are emerging in children, such as maturity onset of diabetes of the young (MODY) and type 2 diabetes.( Botero and Wolfsdorf , 2005). In the last decades, knowledge about Insulin dependent diabetes mellitus (IDDM) epidemiology has made a great advancement. As well as the differences in IDDM incidence based on geographical aspects, registries are able to determine which are the genetic and environmental factors defining the epidemiology of this disease in each population.(Soria et al, 2008). Age, sex, race, genotype, climatology, seasonality and virus infections are the main IDDM risk factors that have been identified. Epidemiologic data are useful to sanitary resort planning and are the point of reference for other studies about aetiology, pathogenesis or disease evolution. (Kishiyama et al, 2006).