Incidence of type 1 diabetes in childhood before and after the reunification of Germany--an analysis of epidemiological data, 1960-2006.

ABSTRACT

OBJECTIVE: To examine the impact of rapidly changing environmental factors on the incidence of type 1 diabetes mellitus (T1D). METHOD: We compared the frequency of T1D in children before and after the reunification of Germany by means of the registries of the German Democratic Republic (GDR, 1960-1989) and of Baden-Wuerttemberg (BW, 1987-2006). The number of cases of diabetes onset in East Germany after the reunification was predicted by a mathematical model. The observed incidence rate in the Eastern part of Germany after the reunification was taken from the literature 1. RESULTS: In Germany, the incidence rate of T1D in children aged 0-14 was 7.2/100 000/year (95%-CI 6.9-7.5, GDR, 1980-1987), and 10.4/100 000/year (95%-CI 9.5-11.4, BW, 1987-1994). For the whole observation period (1960-2006), the observed incidence rates y could be described by the square of a linear function [GDR y=(1.86 + 0.040 * (year - 1960))²; r²=0.85; BW y=(3.03 + 0.085 * (year - 1987))², r²=0.89]. The mean rise in incidence before the reunification was less than half the mean rise after the reunification (mean slope BW 0.085, 95%-CI 0.080-0.090 vs. GDR 0.040, 95% CI 0.036-0.044). The observed incidence for East Germany after 1989 was higher than the prediction on the basis of the GDR -registry (GDR 12.3/100 000/year vs. Saxony 15.7/100 000/year, 95%-CI 14.2-17.3, n=412; 1999-2003). CONCLUSION: We conclude that the basis for the disease progress is a genetic predisposition. Environmental factors may modify changes in incidence of type 1 diabetes but do not determine the overall risk.