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.
Key words
Type 1 diabetes mellitus - epidemiology - incidence - pathogenesis - environmental
factors
