Incidence in young adulthood-onset Type 1 diabetes mellitus in Lithuania during 1991-1997

Our aim was to determine the incidence of Type 1 diabetes mellitus (T1DM) i n the 15-39-yr-old Lithuanian population from 1991 to 1997. A specifically developed communications system with all endocrinologists/diabetologists an d general practitioners involved in diabetes care covering 100% of the samp le Lithuanian population was the initial data source. Annual reports from r egional endocrinologists/diabetologists, death certificates and patients' l ists from Diabetes Societies remained as secondary sources for case ascerta inment, The annual incidence was calculated per 100,000 persons/yr. The tre nd in incidence was estimated by fitting the linear regression model with t he annual incidence data. The total of 769 new cases (496 males and 273 fem ales) of T1DM were recorded among the 15-39-yr-old population during the pe riod 1 January 1991 - 31 December 1997. The average age-standardised incide nce rate was 7.78 per 100,000 persons/yr [95% Poisson distribution confiden ce interval (CI) 7.25-8.35] and was slightly higher among males (9.68 per 1 00,000 persons/yr, 95% CI 8.87-10.57) than among females (5.71 per 100,000, 95% CI 5.07-6.43). Male/female ratio was 1.82 (95% CI 1,69-1,95). Results of the linear regression model showed that the incidence of T1DM in the 15- 39-yr-old population had a tendency to increase. The incidence data of T1DM in Lithuania are appropriate to those in Poland and lower than in other co untries of the Baltic Sea region.