History of cesarean section associated with childhood onset of T1DM in Newfoundland and Labrador, Canada.

OBJECTIVES: Newfoundland and Labrador (NL) has one of the highest incidences of Type 1 diabetes mellitus (T1DM) worldwide. Rates of T1DM are increasing and the search for environmental factors that may be contributing to this increase is continuing. METHODS: This was a population-based case control design involving the linkage of data from a diabetes database with live birth registration data. 266 children aged 0-15 years with T1DM were compared to age- and gender-matched controls. Chi-square analysis and multivariate conditional logistic regression were carried out to assess maternal and infant factors (including maternal age, marital status, education, T1DM, hypertension, birth order, delivery method, gestational age, size-for-gestational-age, and birth weight). RESULTS: Cases of T1DM were more likely to be large-for-gestational-age (P = 0.024) and delivered by C-section (P = 0.009) as compared to controls. C-section delivery was associated with increased risk of T1DM (HR 1.41, P = 0.015) when birth weight and gestational age were included in the model, but not when size-for-gestational-age was included (HR 1.3, P = 0.076). CONCLUSIONS: Birth by C-section was found to be a risk factor for the development of T1DM in a region with high rates of T1DM and birth by C-section. These findings may have an impact on health practice, health care planning, and future research.

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.