Increase in IDDM incidence in Bulgarian children (1974-1995)

The incidence of insulin-dependent diabetes mellitus (IDDM) in children on the Balkan peninsula varies between 2.45 and 10.00/100,000. The present study aimed to assess the trends in the IDDM incidence in children 0-14 years for a 22-year period in Eastern Bulgaria. The data were collected on the basis of the Varna Paediatric Diabetes Registry, both retrospectively and prospectively, with ascertainment of the primary source up to 98.8%. The mean annual IDDM incidence was 6.32/100,000 (95% CI 5.91-6.78), with the incidence in towns significantly higher than in villages: 7.24 vs 4.58/100,000, p < 0.0001. A linear trend of increase in the incidence with time was found, applying Poisson regression analysis. According to the model the age-adjusted incidence rose by 1.9% annually. The analysis revealed a significant linear trend of increase for children living in towns and for those aged 10-14 years.