Incidence of childhood diabetes in The Netherlands: a decrease from north to south over north-western Europe?

The incidence of childhood diabetes (0-19 years of age) in The Netherlands, where there is no nationalized health-care system, was investigated retrospectively in the years 1978 to 1980 inclusive. The method chosen was a questionnaire among all Dutch paediatricians and internal physicians acting as consultants. Ascertainment was by the same questionnaire held separately among the large Dutch membership of the Dutch Diabetes Association, employing the capture-recapture census method for calculation. For paediatricians the ascertainment was 94%, for specialists in internal medicine 75%. Before correction for ascertainment 1271 children were registered in the two surveys. The ascertainment-corrected annual incidence was 10.95/100000 for 0-19-year-old children, lower than in any other ascertained survey in north-western Europe published so far. The male:female ratio was the same as in other studies and no local geographical differences were found. Seasonal variation was absent in children 0-10 years old in the month the first insulin injection was administered. The data support the influence of unknown exogenous factors associated with the clinical onset of childhood diabetes.