AIM: This study investigated whether perinatal factors influenced the risk of a double diagnosis of type 1 diabetes and coeliac disease.

METHODS: We used multinomial logistic regression models to study the associations between perinatal factors, gender, mode of delivery, season of birth and the risk of type 1 diabetes, coeliac disease or both, in Swedish-born singleton children.

RESULTS: We found that 4327 of the 768 395 children (0.6%) had been diagnosed with type 1 diabetes, 3817 (0.5%) had been diagnosed with coeliac disease and 191 (0.02%) were affected by both diseases. If the children already had type 1 diabetes (n = 4518), the absolute risk of being affected by coeliac disease increased to 4.2% (n = 191). Children with both type 1 diabetes and coeliac disease were more likely to be female (OR = 1.48, 95% CI = 1.01-1.97), delivered by Caesarean section (OR = 1.60, 95% CI = 1.07-2.39), have native-born Swedish mothers (OR = 4.84, 95% CI = 1.96-11.97) or be born during the summer months (OR = 1.43, 95% CI = 1.07-1.92).

CONCLUSION: The increased risk of being affected by a double diagnosis of type 1 diabetes and coeliac disease was modulated by perinatal risk factors. This suggests that early life events are important when it comes to children with type 1 diabetes also developing coeliac disease.