Changes in causes of death in diabetic patients based on death certificates during a 30-year period in Osaka District, Japan, with special reference to cancer mortality.

As reported previously, we have conducted studies on causes of death among diabetic patients during the 25-year period, from 1960 to 1984, in Osaka District, Japan. We have now added the most recent 5-year data, for 1985-1989, and analyzed changes in causes of death during the entire 30-year period as a whole. The subjects studied were those for whom a total of 32,222 death certificates had been filed in Osaka Prefecture, from 1960 to 1989, with diabetes mentioned either as the underlying cause or as a contributory condition. The relative number of death certificates mentioning diabetes as the underlying cause, which had been decreasing during the 25-year study period, showed a further decrease, reaching the lowest value, 33.4%, for the period 1985-1989. The mean age at death exceeded 70 years for all causes of death, showing a continuous increasing trend. An increase in disease of the heart and a decrease in cerebrovascular disease were observed, making the difference between the two causes greater since 1980-1984. Malignant neoplasms, ischemic heart disease, and pneumonia and bronchitis also showed steady increases. The O/E ratios (ratio of observed/expected number of deaths) for cirrhosis of the liver and tuberculosis were markedly increased, while that for malignant neoplasms was only about 0.5, suggesting extreme underestimation of the number of diabetic cases with cancer. Among malignant neoplasms, an increasing trend in liver cancer was remarkable and was associated with a relatively high O/E ratio.