Spatial clustering in childhood diabetes: evidence of an environmental cause.

If environmental factors are important in the aetiology of insulin-dependent (Type 1) diabetes mellitus, primary schooling would be more likely to be shared by cases in an epidemic year compared with controls. We have examined a case control study, comparing primary schools attended. Cases were identified from an established register with known accurate ascertainment and compared with controls taken from a central register of all children and date of birth, sex, and race matched. Parents were asked to complete a structured questionnaire which included questions relating to the child's schooling. There were 187 cases with at least a first matched control. Thirty-two of the cases attended the same nursery or primary school as another case, 18 in the same academic year, compared with 12 controls attending the same school as another control (99% confidence interval (CI) for the difference between proportions 0.0572 - 0.107). Of these cases diagnosed in 1986, 9 attended the same school as another case. Spatial clustering occurs in Type 1 diabetes. This is further evidence of an environmental factor contributing to the genesis of the disease.

Cow's milk and type 1 childhood diabetes: no increase in risk.

A retrospective case-control study was undertaken to investigate the relationship between the early introduction of cow's milk and the subsequent risk of developing Type 1 diabetes (< 15 years at diagnosis). A total of 268 children who developed diabetes during the period 1980-1990 (11 years inclusive) in Leicestershire were identified. Age-, sex-, and race-matched controls were identified using the Leicestershire population register. Parents of children with diabetes and their controls completed a structured questionnaire on infant feeding habits from birth. A total of 184 questionnaires (67%) were analysed. There was no difference between the diabetic and control children with respect to the introduction of cow's milk at an early age and the risk of developing diabetes (odds ratio: 0.98 (0.65-1.47)). In addition, short duration of breast-feeding (< 3 months) had no influence on the incidence of diabetes (1.05 (0.64-1.75)). This study does not support the hypothesis that the early introduction of cow's milk or a short duration of breast-feeding increases the risk of developing Type 1 diabetes.