Incidence of Type 1 Diabetes in Lithuanians Aged 0–39 Years Varies by the Urban-Rural Setting, and the Time Change Differs for Men and Women During 1991–2000

Abstract

OBJECTIVE—Type 1 diabetes has been associated with factors related to welfare and social class. During the past decade, Lithuania has experienced a transition period, leading to dramatic changes in the socioeconomic structure of the society. RESEARCH DESIGN AND METHODS—Incidence in the group aged 0–39 years by urban-rural setting (cities >100,000 inhabitants, towns, and rural areas), period (1991–1995 and 1996–2000), age, and sex were studied using Poisson regression. RESULTS—The age- and sex-standardized incidence per 100,000 inhabitants per year was higher in men aged 0–39 years than in women (9.5 and 6.9, respectively, incidence rate ratio [IRR] = 1.39, P < 0.001). Incidence was lower in rural areas than in towns and cities (7.1, 9.0, and 8.8, respectively, P < 0.001). The urban-rural differences in incidence were most marked among children aged 0–9 years. From 1991–1995 to 1996–2000, the overall incidence increased from 8.7 to 10.5 (IRR = 1.22, P = 0.001) in men and from 6.2 to 7.8 (IRR = 1.25, P = 0.002) in women. For men, the increase over time occurred predominantly in the cities, from 8.4 to 11.8 (IRR = 1.40, P < 0.001), and in the older age-groups. In contrast, for women, the incidence increased more in small towns and rural areas, from 5.8 to 7.7 (IRR = 1.33, P = 0.003), and in the younger age-groups. CONCLUSIONS—The incidence of type 1 diabetes in Lithuania differs depending on the urban-rural setting, and the pattern of change over time differs between the sexes, both by urban-rural setting and age-group. The findings support the theory that lifestyle-related factors connected to socioeconomic status are important for the occurrence of type 1 diabetes.