ABSTRACT

Type 1 diabetes mellitus is mainly a disease of white populations with marked geographical variation in incidence. The incidence is highest in Finland (50/100000 per year under 15 years) and other northern European countries, but there are anomalies. Sardinia has an incidence of more than 30/100000 per year. Japan, on the other hand, has an incidence of only around 2/100000 per year. However, in almost all areas studied, the annual incidence is rising at a rate (often around 2-3 per cent per annum) hugely greater than that which could be explained by genetics. Careful study (e.g. via the EuroDiab programme) has established that these are true secular trends and not simply a result of improving registration systems.