Incidence of insulin dependent diabetes in England: a study in the Oxford region, 1985-6

Abstract

Objective: To determine the incidence of insulin dependent diabetes mellitus up to the age of 21 in a geographically defined population in England with independent validation of completeness of case ascertainment.

Design: Prospective registration of newly diagnosed cases supplemented by centralised hospital discharge records and death certificates. Validation of ascertainment from general practitioners.

Setting: Oxford Regional Health Authority area (population 2.4 million).

Patients: All patients with insulin dependent diabetes diagnosed below age 21 during 1985-6 and resident in the region at the time of diagnosis.

Interventions: None.

End point: Validation of a method of case ascertainment for assessing temporal variation in incidence of insulin dependent diabetes.

Measurements and main results: The overall yearly incidence of newly diagnosed insulin dependent diabetes mellitus in people under 21 was 15.6 cases/100,000 (95% confidence interval 13.6 to 17.6). Among males the incidence was 16.8 cases (14.0 to 19.7)/100,000 and among females 14.3 cases (11.6 to 17.1)/100,000. The highest incidence, in the 10-14 year age group, was 26.4 (20.9 to 31.8) new cases/100,000 population yearly. Case ascertainment was greater than 95%.

Conclusions: The incidence of insulin dependent diabetes in England is considerably higher than reported from large scale studies. It is consistent with described patterns of geographical variation. The figures provide a baseline for assessing temporal change.