The natural history of insulin-dependent diabetes in Denmark: 2. Long-term survival--who and why.

Forty per cent of all Danish insulin-dependent diabetic (IDDM) patients survive for at least 40 years after diagnosis. In an attempt to identify factors influencing the probability of surviving for 40 years or more, we followed all IDDM patients diagnosed before 1943 and admitted to the Steno Memorial Hospital. Patients surviving greater than or equal to 40 years were compared with patients dying within 35 years of diabetes diagnosis. Patients dying within 35 years were characterized by male preponderance (p less than 0.01), poor metabolic control (p less than 0.05), and by less frequent attendance at a specialized care unit (p less than 0.0001). Death due to uraemia/diabetic nephropathy was also characterized by male preponderance, poor metabolic control, and few contacts with a specialized care unit but in patients dying from cardiovascular disease (CVD), no effect of sex was found, indicating that the protection from CVD found in the female non-diabetic population is absent in IDDM patients. We conclude that long-term survival with IDDM may be determined by factors susceptible to intervention such as metabolic regulation and patient attitude to their disease.