English summary: EXCESS MORTALITY HAS REMAINED HIGH AMONG PEOPLE WITH DIABETES

Background

The number of people with diabetes is increasing in Finland. While mortality has decreased both among the Finnish general population and among diabetic people, previous studies have shown that mortality among diabetic people is still very high compared to mortality among non-diabetic people. The present study examines changes in mortality among people with diabetes in 1996-2007. It also explores the extent of and changes in excess mortality due to different causes of death among people with insulin-dependent and non-insulin-dependent diabetes.

Methods

The total diabetes population between 1996 and 2007 was obtained from the FinDM II database, which includes persons with diabetes identified from different Finnish health registers. Mortality was studied in 15-year age groups per 1000 person years. Trends in mortality were scrutinised in three periods (1996-99, 2000-03 and 2004-07). Excess mortality was calculated as the difference between the mortality among diabetic people and the mortality among the Finnish general population. The relative risks of excess mortality and the statistical significance of interaction terms were obtained from Poisson regression models.

Results

According to the register data, there were 284 832 diabetic people in Finland at the end of 2007. Compared with year-end data from 1995, the prevalence of diabetes has increased by 83%. Mortality among people with diabetes decreased in almost all age groups. Between 2004 and 2007, excess overall mortality among people with insulin-dependent diabetes aged 30-79 was more than threefold among men and fourfold among women compared to the Finnish general population of the same age. Excess mortality associated with coronary heart disease was more than eightfold among diabetic women and more than fourfold among men. Among women with insulin-dependent diabetes, a statistically significant increase was observed in excess mortality from cancer and coronary heart disease. For people with non-insulin-dependent diabetes, overall mortality was 1.65 times higher among women and 1.75 times higher among men than among the whole population of the same age. No statistically significant increase was found in excess mortality due to any cause of death among people with non-insulin-dependent diabetes.

Conclusion

Although mortality among diabetic people has decreased, significant excess mortality was still found in this population. Mortality among people with non-insulin-dependent diabetes compared to the whole population decreased especially with regard to circulatory diseases. This may have been due mainly to better preventive and acute treatment practices for circulatory diseases. Further research is needed on reasons for the increased excess mortality among people with insulin-dependent diabetes.