Excess mortality from diabetes mellitus during epidemics of influenza was studied with the purpose of assessing the impact of influenza infection on diabetic patients.
Monthly mortality rates for the period 1961 to 1974 were taken from Monthly Report of Vital Statistics published by the Ministry of Health and Welfare, Japan. Expected mortality rates were obtained by the method of Serfling, i. e. from the regression equation, y=a+bt+csin (πt/6-θ), where coeffitients a, b and c were computed by the least square method. Relative intensity (excess mortality rate/standard deviation) was used as a measure of the statistical significance of excess mortality.
Large peaks of excess mortality due to respiratory diseases (pnuemonia, bronchitis and influenza) appeared during seven epidemic periods, defined by statistics based on reported cases of influenza. Mortality from diabetes mellitus increased significantly during three epidemics and nearly signif icantly during one epidemic out of seven epidemics of influenza. Fasting blood sugar levels were elevated in about 70% of diabetic patients during influenza-like illness in the winter of 1975-1976, at which time influenza A was prevalent.
Because of the increased risk of influenza associated death, the protection of patients from influenza is important in the management and control of diabetes.