Case-Control Study of IDDM

Insulin-dependent diabetes mellitus (IDDM) may be caused by a combination of genetic predisposition and environmental insults. However, there are few solid leads concerning human diabetogenic environmental agents. A case-control study was carried out to investigate the possible relationships between IDDM and various biological, chemical, and psychological factors. All 161 cases of IDDM among children aged 0–17 yr occurring in Montreal from 1983 to 1986 were included. The parent of each newly diagnosed diabetic subject was asked to provide the names of two of the child's friends or neighbors who would be age and sex matched to serve as controls. For those unable to do so, matched controls were selected from a hospital emergency room. Parents of cases and controls were interviewed concerning many factors. There was little or no difference between cases and controls with regard to parental smoking habits, exposure to pets, and consumption of meat products high in nitrosamines. In univariate analyses, there was some indication of elevated risk for children who had not been breast-fed, who attended day care or nursery before age 5 yr, who lived in a crowded household at age 3 yr, or who had a history of asthma or eczema, although in multivariate analyses the only variables that had any effect were crowding and day-care attendance. In univariate and multivariate analyses, there was high risk of IDDM among children who had experienced selected stressful life events during the 12 mo preceding onset of IDDM or who had exhibited symptoms of social or psychological dysfunction during that time. Some of these apparent effects may have been due, in part, to biases induced by the method of selecting controls and to the interview process.