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

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.