Prediction model for the incidence and prevalence of type 1 diabetes in childhood and adolescence: evidence for a cohort-dependent increase within the next two decades in Germany

Ehehalt S, Dietz K, Willasch AM, Neu A; for the DIARY-Group Baden-Wuerttemberg. Prediction model for the incidence and prevalence of type 1 diabetes in childhood and adolescence: evidence for a cohort-dependent increase within the next two decades in Germany. Objective: To provide data on type 1 diabetes (T1D) epidemiology in childhood over a period of 20 years and to predict prevalence and cohort-age-specific incidence rates (IRs) for the next two decades in Germany. Methods: The Baden-Wuerttemberg Diabetes Incidence Registry (DIARY) includes children and adolescents below 15 years of age with new onset of T1D (period 1987–2006, n = 5108 cases). Results: The mean age- and sex-standardized IR was 15.3/100 000/year (95% CI 14.8–15.7) and the average increase in the IR was 4.4% per year (95% CI 3.9–4.9). Within the next 20 years (2007–2026), the risk for developing diabetes will increase like the square of a linear function with calendar year for all age ranges. There is a strong correlation between the predicted IRs of the cohorts and the observed IRs (n = 300; root mean square error = 0.56; r2 = 0.71) and a negative correlation between mean age at onset and T1D IR (p = 0.02). On 31 December 2006, the prevalence of T1D was 0.126% (95% CI 0.121–0.132). The predicted prevalence (end of 2026) is estimated to be 0.265% (95% CI 0.25–0.28; predicted cases: n = 2950; 95% CI 2900–3000). Conclusions: In comparison to observations made in the past, the risk of disease rises even faster than expected: The younger the child, the quicker the increase of the cohort-age-specific IR and the higher the risk for T1D during lifetime.