The epidemiology of Type 1 diabetes mellitus is not the same in young adults as in children

Aims/hypothesis. This prospective study examined the epidemiology of Type 1 diabetes in young adults in Europe. Methods. We ascertained incident cases of Type 1 diabetes in the 15 to 29 years (both inclusive) age group throughout Europe over a period of 2 years. Diabetes registries in nine countries, in which incidence rates for Type 1 diabetes in the 0 to 14 age group were available, took part. Incidence rates were estimated per 100000 person years and standardised for sex and age. Cumulative incidences per 1000 from birth to age 30 were estimated. Heterogeneity between centres was tested with a Poisson regression model. Results. A total of 2112 diabetes cases were ascertained in 1996 and 1997, of which 61.4% were considered to be Type 1 diabetes. Completeness of ascertainment varied from 70 to 90%. Standardised incidence varied from 4.8 per 100000 person years to 13.4 per 100000 person years. The male-female ratio was estimated to be one or more, and in the 25 to 29 age group 1.5 or more in all countries. Cumulative incidences for males and females indicate that the former exceeds the latter from age 24. In the two centres with highest childhood incidence, this applied already from 14 years of age. Conclusions/interpretation. The incidence of Type 1 diabetes in adults is lower than in children and the range of incidence is also reduced, with a less than threefold variation in adults, against an eightfold variation in children. There is a male excess in incidence, especially in the age group 25 to 29 years.