Very high and increasing incidence of type 1 diabetes mellitus in Newfoundland and Labrador, Canada.

Objective: To determine the incidence of type 1 diabetes mellitus (T1DM) among children aged 0-14 yr inclusive in the Canadian province of Newfoundland and Labrador (NL).

Methods: Prospective and retrospective cohort study of the incidence of T1DM in children aged 0-14 yr from 1987 to 2005. Identified cases during this time period were ascertained from several sources and verified using the capture-recapture technique.

Results: Over the study period, 732 children aged 0-14 yr were diagnosed with T1DM. The incidence of T1DM in this population over the period 1987-2005 inclusive was 35.08 per 100,000 (95% confidence interval: 32.54, 37.62). The incidence over this period increased linearly at the rate of 0.78 per 100 000 per year. There was a significant difference between the incidence of 31.61 per 100,000 for boys in the 0-4-yr age-group and 19.05 per 100,000 for girls in the 0-4-yr age-group (p = 0.001). The incidence was very high throughout the entire province.

Conclusions/interpretation: The province of NL has one of the highest incidences of T1DM reported worldwide. The incidence is increasing over the 19-yr study period.