Epidemiologic survey of juvenile-onset diabetes in Montreal.

Active search of hospital records was used to survey insulin-dependent juvenile-onset diabetics younger than 17 years resident in General Montreal at the time of onset of symptoms during a seven-year period (1971-1977). A mean annual incidence of 8.8/100,000 was found with variation from year to year (5.8 to 10.3). Eighty percent were five years of age or more at time of diagnosis, and the increase with advancing age was similar to that seen in other studies including the somewhat earlier increase in incidence among females. Seasonal peaks were noted in some but not all years and were more marked in years of high incidence and among males. More cases occurred in areas of high socioeconomic level as measured by average family income. The estimated incidence among siblings of diabetics is 15 times the incidence in the general population. Ten percent of diabetics have a first degree relative who is insulin dependent.