Despite major advances in management and care, type 1 diabetes remains associated with considerable premature mortality. Although significant improvements in life expectancy have been observed in those diagnosed since 1965, mortality rates among patients with type 1 diabetes remain significantly higher than the general population, a finding confirmed by several studies in the United States and internationally, with standardized mortality ratios revealing that patients with type 1 diabetes have mortality rates that are 3–18 times higher than would be expected in their respective countries. There is marked geographic variation in mortality, and further notable differences between males and females, compared to the general population.
Deaths due to diabetes-related acute and chronic complications appear to account for nearly all of the excess premature mortality in patients with type 1 diabetes compared to the general population. Diabetes-related chronic complications, particularly cardiovascular and renal disease, are now the predominant causes of death in type 1 diabetes, in contrast to the high rates of death due to diabetes-related acute complications (i.e., glycemic-related events) observed during earlier years (i.e., the pre-insulin era). End-stage renal disease (ESRD), historically, is the leading cause of death in the mid-years of diabetes duration (up to 35 years), accounting for more than half of deaths. After 35 years duration, however, cardiovascular disease (CVD) is the leading cause of death, accounting for two-thirds of deaths. With the decline (or delay) in developing ESRD due to improvements in diabetes management, this pattern may be changing.
Several risk factors for type 1 diabetes mortality have been investigated. Females with type 1 diabetes continue to have a greater increase in mortality compared to females in the general population than is found for males. This pattern is consistent for all causes of death, particularly CVD, where the standardized mortality ratio for females (24.7) is nearly three times that for males (8.6), primarily resulting from the lower rates of mortality in the female general population. In addition, African Americans remain at increased risk of premature mortality compared to Caucasians, consistently having mortality rates 2.5 higher than their Caucasian counterparts over the past 30 years. Onset of type 1 diabetes after puberty also appears to be associated with 1.5–2.0-fold higher mortality than prepubertal onset. Several other factors are associated with type 1 diabetes mortality, including lower socioeconomic status, hypertension, smoking, and renal failure. Some risk factors, such as glycemic control and insulin resistance, have not consistently shown direct associations with type 1 diabetes mortality but are associated with diabetes-related chronic complications and are likely contributing factors. Indeed, the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications study suggests that even 6 years of more intensive therapy may lead to a lower mortality over 20 years of further follow-up.
Finally, type 1 diabetes has a greater impact on mortality rates in U.S. populations than seen in many European countries, with U.S. standardized mortality ratios of 6.9–7.5 compared to European standardized mortality ratios of 3.3–4.2. These geographic differences indicate an urgent need to improve disease management and access to care in the United States.