Major childhood infectious diseases and other determinants associated with type 1 diabetes: a case-control study

Aims - Evaluation of the association among infectious diseases and other events pertaining to childhood medical history and type 1 diabetes. Methods - A case-control study was carried out, taking as cases 159 type 1 diabetic patients (0-29 years) recorded from 1988 to 2000 within the population registry of the Pavia province (North Italy). As controls 318 non diabetic subjects were matched by age and sex. A questionnaire was administered by standardised interviewers. Data were analysed by conditional logistic regression. Results - Viral childhood diseases (OR 4.29; 95%CI 1.57-11.74) and bottle feeding (OR 1.83; 95%CI 1.08-3.09) were directly associated to type 1 diabetes; an inverse association was found for vitamin D administration during lactation (0-14 years) (OR 0.31; 95%CI 0.11-0.86) and for history of scarlet fever in both sexes and age groups (OR 0.19; 95%CI 0.08-0.46). Conclusions - Most associations of the studied variables confirm already known findings. The significant inverse association of type 1 diabetes with scarlet fever history is a peculiar finding, whose meaning is still obscure, although it has been recently described that streptococcal A infections are regulated by HLA class II alleles.