INCIDENCE TRENDS IN CHILDHOOD-ONSET IDDM IN 4 COUNTRIES AROUND THE BALTIC SEA DURING 1983-1992

We present secular trends of childhood onset insulin-dependent diabete s mellitus (IDDM) in Finland, Estonia, Latvia and Lithuania during the period of 1983-1992. Incidence data were obtained from the national I DDM registries. The average age-standardized Incidence per 100000/year was 35.0 in Finland, followed by 10.2 in Estonia, 7.1 in Lithuania an d 6.5 in Latvia. A male excess in incidence was recorded in Finland (1 .15) and Latvia (1.01). In all countries, the highest age-specific ris k of IDDM was observed in the 11-13 year age range. The large differen ce in incidence between Finland and other Baltic countries was seen ev en in 1-2-year-old children. During the 10-year study period overall c hanges in incidence of IDDM were relatively small in these four countr ies. The incidence increased in Finland and Lithuania on average by 1% and 1.4% per year, respectively. A statistically significant increase was recorded only in 0-4 year old children in Finland, at 5.6% per ye ar. In Estonia, an 8.3% increase in this age group, however, was not s tatistically significant. The different trends in the age-group specif ic incidence rates were confirmed in Finland. In conclusion, from 1983 to 1992 the incidence of childhood onset IDDM was increasing in Finla nd and Lithuania, while in Latvia and Estonia it was stable. There are still great differences in IDDM incidence between the countries aroun d the Baltic Sea.