In some cases, however, the rate of decline is no different than that of the general population, according to new research.
A new analysis of type 1 diabetes (T1D) outcomes from 6 countries shows that mortality rates from the disease have declined since 2000, although excess mortality compared with the general population remains high.
The study was published in Diabetologia, and it is based on data from Australia, Denmark, Latvia, Scotland, Spain, and the United States.
Rates of mortality from diabetes have been on the decline for the past 50 years, alongside an overall decrease in age-standardized mortality, explained the authors. Yet, most mortality studies looking specifically at T1D have focused on children and young adults, even though diabetes-related deaths among these age groups are rare.
“Secular mortality trends in middle-aged and older adults, for whom chronic complications dominate the causes of death, and among whom the vast majority of deaths of T1D occur, may differ markedly from younger adults,” the investigators noted. Moreover, they wrote that patients with T1D might also face a higher risk of death from causes not directly related to diabetes.
The investigators decided to use population-based databases in the 6 countries to better understand how all-cause mortality risk among patients with T1D has changed in recent years and how those changes track with variance in all-cause mortality in the general populations of those countries. The data for most of the countries was based on national health care and diabetes databases. In the case of the United States, the data came from Kaiser Permanente Northwest. The years analyzed varied by country, but overall, they cover 2000 to 2016 and include 1.5 million person-years.
The data show that country-by-country annual changes in age- and sex-standardized all-cause mortality among people with T1D dropped by between 2.1% and 5.8% over the study period. Australia had the lowest rate of decline, and Denmark had the largest.
Men and older patients tended to have higher rates of all-cause mortality, the data show, but those factors did not appear to affect the rate of decline. When the investigators used standardized mortality ratios (SMRs) to compare changes in mortality among patients with T1D to the general population, they found the ratio was higher in females than in males and peaked between ages 40 to 70 years.
Still, despite the positive trend in mortality among people with T1D, the investigators said the comparisons to general-population mortality trends provide important nuance. Even though all-cause mortality among T1D dropped in all 6 countries, the SMR—a reflection of excess mortality among people with T1D vs the general population—only declined in Denmark, Scotland, and Spain. That means the rates of decline in Australia, Latvia, and the United States merely tracked with declines in mortality among the general population.
“Despite reductions in absolute all-cause mortality rates, and, in some countries, in the SMR, T1D still confers a higher excess risk of death compared with individuals without diabetes,” the authors wrote.
They said suboptimal glycemic control and the presence of complications are key reasons for the higher risk and concluded that driving down excess mortality in T1D will continue to be a challenge in the coming years and decades.
“Considering the increasing incidence of T1D observed in younger populations in recent years, it is critical to continuously improve the multidimensional management of T1D, particularly among younger populations,” they wrote.
Ruiz PLD, Chen L, Morton JI, et al. Mortality trends in type 1 diabetes: a multicountry analysis of six population-based cohorts. Diabetologia. 2022;65(6):964-972. doi:10.1007/s00125-022-05659-9