Epidemiological studies of diabetes mellitus in Denmark: 3. Clinical characteristics and incidence of diabetes among males aged 0 to 19 years.

This study presents the clinical-epidemiological analysis of data from 769 individuals, representing greater than 95% of all cases of diabetes mellitus diagnosed during the first 20 years of life among the Danish male birth cohorts 1949-1956 inclusive. It is concluded that except for a very few, all cases of diabetes developing during the first 20 years of life are insulin-dependent with a duration of symptoms less than 2 months before diagnosis in greater than 75% of the cases. The cases were evenly distributed within Denmark at the time of birth as well as of diagnosis, and greater than 98% were admitted to hospital at diagnosis. A relatively higher proportion of cases diagnosed during autumn and winter periods was found, but was not statistically significant. Incidence was analysed in a regression model with age and calendar time as variables; the variation of age at onset was similar to previous studies with a peak at pre-school age and at puberty. Contrary to previous Danish analyses, we found a significant calendar time variation with steadily increasing age-specific incidences from the beginning of 1950s until an apparent maximum in mid-1970s.