Objective: The accelerator/beta-cell stress hypothesis regards insulin resistance as one common basis for type 1 and type 2 diabetes and weight increase as an important trigger of type 1 diabetes. To test this hypothesis, we examined children's height and weight gain from birth to the time of diagnosis of type 1 diabetes. Method: Growth charts (n=316) from children 0-16yr old up to the time of diagnosis of type 1 diabetes were compared with growth charts from age- and sex-matched controls. Results: Compared with their controls, children who developed diabetes had experienced more pronounced gain in both weight and height. In the year of diagnosis, they were taller [0.5 vs. 0.36 standard deviation score (SDS), p<0.03] and heavier (0.7 vs. 0.45 SDS, p<0.01). Children who developed diabetes aged 5yr or less gained more weight during the period between their third month and third year of life (p<0.01). Children who were diagnosed between 6 and 10yr of age had gained more in height before they were 5yr old (p<0.05). Regression analysis showed that a high weight or a high body mass index (BMI) at 5yr of age indicated, more than the other measurements, a high risk for diabetes later during childhood, while height and weight at ages less than 5yr did not add any further information on diabetes risk. Conclusions: Rapid growth before 7yr of age and increased BMI in childhood are risk factors for later type 1 diabetes. These findings support the accelerator/beta-cell stress hypothesis. © 2008 The Author Journal compilation © 2008 Blackwell Munksgaard.