Incidence of insulin dependent diabetes in children aged under 15 years in the British Isles during 1988

Abstract

Objective: To ascertain the annual incidence rate of insulin dependent diabetes diagnosed in children under the age of 15 years in the British Isles during 1988, and to compare the results with an earlier study carried out in 1973-4.

Design: Active monthly reporting of cases by consultant paediatricians, with additional input from diabetologists and all specialist diabetes nurses and health visitors.

Setting: British Isles (England, Wales, Scotland, Northern Ireland, Republic of Ireland) with a total population at risk of 11,819,000 children.

Patients: All children diagnosed under the age of 15 years with primary insulin dependent diabetes from 1 January to 31 December 1988 and resident in the British Isles at diagnosis.

Main outcome measures: National incidence rate of insulin dependent diabetes; differences in incidence rates between regions and between three age groups: 4 and under, 5-9, and 10-14 year olds.

Results: 1600 children (837 boys and 763 girls) had a confirmed diagnosis of insulin dependent diabetes, giving a national incidence rate of 13.5/100,000/year (95% confidence interval 12.9 to 14.2/100,000/year). This was considerably higher than the incidence rate of 7.7/100,000/year in children under the age of 16 years reported in the British Diabetic Association's study of 1973-4. The age-sex adjusted rates varied between regions, ranging from 6.8/100,000/year (Republic of Ireland) to 19.8/100,000/year (Scotland). There were considerable differences in the numbers of cases diagnosed each month, with the 10-14 year age group showing the most seasonal variation. A quarter of the children (404/1600) were under 5 years old. Case ascertainment was estimated as 90%.

Conclusions: Insulin dependent diabetes in the British Isles does not seem to occur uniformly over time or geographical area. Even allowing for differences in ascertainment between the 1973-4 and 1988 studies, there seems to have been an increase in the incidence rate of insulin dependent diabetes in children under the age of 15 years during the 15 year time period. If diabetes is becoming more common in this age group, possibly by developing earlier in susceptible children, this would be a matter of considerable public health concern.