INCIDENCE OF INSULIN-DEPENDENT DIABETES-MELLITUS IN AGE-GROUPS OVER 30 YEARS IN DENMARK

The incidence of IDDM in the age group over 30 years was estimated in a historical prospective study, using clinical and biochemical measure ments at onset as criteria for classification. The study Population, n early one million, represents 20% of the Danish population. The degree of ascertainment was >99%. One thousand two hundred and forty patient s were treated with insulin during the study period (1973-77). Based o n the clinical and biochemical variables, the patients were classified into three groups: insulin-dependent diabetes mellitus (IDDM) account ed for 16.2%, insulin-treated diabetes mellitus for 54.1% and short-te rm treated diabetes mellitus for 29.6% of the total insulin-treated gr oup. The incidence of IDDM in the age group over 30 years at onset was 8.2 100 000-1 year-1. The cumulative incidence rate (0-90 years) was 1.5-1.6 per cent. The present study indicates that IDDM may develop,at any age. Thus the life-time risk of developing IDDM is higher than hi therto expected.