Objective: To evaluate whether the increased risk of type 1 diabetes conferred by an early introduction of cow's milk supplements can be mediated by accelerated growth in formula-fed infants.
Research design and methods: All children < or = 14 years of age who were diagnosed with type 1 diabetes from September 1986 to April 1989 were invited to participate in the study. Birth date- and sex-matched control children were randomly selected from the Finnish Population Registry. At least three weight measurements from the first year of life were obtained for 435 full-term diabetic subjects and 386 control subjects from well-baby clinics and school health care units.
Results: Increase in body weight was greater in the diabetic girls than in the control girls, and the difference increased from 111 g (95% CI 0-218, P = 0.04) at 1 month of age to 286 g (95% CI 123-450, P = 0.0006) at 7 months. For boys, the difference in weight between the diabetic subjects and the control subjects remained stable during infancy (difference 95 g, 95% CI-2-205, P = 0.09). Increased weight was associated on average with a 1.5-fold risk of type 1 diabetes. Early introduction of formula feeding (< 3 vs. > or = 3 months) was also associated with an increased risk of type 1 diabetes after adjustment for the individual weight gain curve (adjusted odds ratio 1.53, 95% CI 1.1-2.2). No evidence for interaction was observed.
Conclusions: These observations indicate that an early exposure to cow's milk formula-feeding and rapid growth in infancy are independent risk factors of childhood type 1 diabetes.