Early infant feeding and risk of type 1 diabetes mellitus - a nationwide population-based case-control study in pre-school children

Background The evidence on the role of environmental factors in the development of type I diabetes is conflicting. Reducing potential bias and the variety of exposures, we investigated the association between type 1 diabetes risk and nutritional and environmental exposures in pre-school children. Methods This nationwide population-based case-control study included 760 cases under 5 years of age newly diagnosed with type 1 diabetes during 1992-1995. From the general population, 1871 controls were randomly selected and individually matched on age (+/- 1 year), sex, and residence. information on infant diet, foetal, perinatal and socio-economic factors, and familial diabetes was obtained by a parent-administered questionnaire. Data were analysed by multiple conditional logistic regression. Results Duration of breastfeeding and age at introduction of bottle-feeding were inversely associated with type 1 diabetes risk according to a dose-response relationship (trend test p < 0.05). Adjusted odd ratios (95% CI) for a long breastfeeding period and a late introduction of bottle-feeding (>= 5 month versus <2 weeks) were 0.71 (0.54-0.93) and 0.80 (0.62-1.04), respectively. Familial type 1 diabetes, maternal age >40 years, and low birth weight were found more frequently among diabetic than among control children. Current cow's milk consumption, higher social status, and a larger family were associated with a reduced diabetes risk. Up to one half of the diabetic cases in the population could be attributed to modifiable exposures. Conclusions Our findings indicate that infant feeding is associated with type I diabetes risk and that a considerable part of new type 1 diabetic cases is potentially preventable. Copyright (C) 2007 John Wiley & Sons, Ltd.