Relation between occurrence of type 1 diabetes and asthma

A negative association has been observed between type 1 diabetes and atopic diseases in individuals, a finding that supports the Th1/Th2 paradigm. By using published data on disease occurrence in different countries, we show a strong positive association between the occurrence of type 1 diabetes and symptoms of asthma at the population level in Europe and elsewhere. Our finding suggests that there may be common factors influencing susceptibility to the two disorders at the country level. Our observation must be accommodated in explanations of the epidemiology of type 1 diabetes or atopic diseases.