Incidence of diabetes mellitus in Oslo, Norway 1956-65

Abstract

A study of the incidence of diabetes mellitus in Oslo for the period 1925-54 (Westlund, 1966), based on a comprehensive compilation of hospital documents, was extended to 1956-65. The incidence rates for the 2 periods were compared by taking the year of diagnosis and age at diagnosis in each case. The incidence rates for 1925-54 were revised by adding cases for this period discovered during the 1956-65 study, and showed no major changes. In particular, few new cases were found that were diagnosed during the 2nd wold war, so that the dramatic reduction in incidence shown in Westlund''s paper is not affected. The trend is fairly constant, with 2 exceptions: there was an increase in incidence for boys and girls younger than 10 yr and a decrease for women aged 40-59 yr. After considering the various sources of error in such as comparison it is concluded that since 1950 there may have been a real increase in rates of diabetes in children. The decrease in rates for middle-aged women is not supported by mortality data for which statistics are given for associated and for underlying causes. Mortality data are difficult to interpret, and by relying on hospital documents and death certificates considerably higher incidence rates were presented than would have been the case had the incidence estimations been based on death certificates alone. The incidence rates in 1956-64 for children tally fairly well with those reported for Great Britian and Ireland (Bloom et al., 1975) and for nothern Norway (Bratlid, 1976).