Type 1 Diabetes and Mortality
Do New Insulin Regimens and Increasing Technology Improve Survival Rates?
Much has been written about the improved quality-of-life that has been associated with the analog insulins, basal/bolus multiple daily dose injections, and insulin pump therapy. With the addition of continuous glucose sensors, tighter glycemic control with decreased hypoglycemia is even more possible resulting in fewer fluctuations of blood sugar and improved hb A1c's. However, the significant question remains, have we improved the mortality rate in people with type 1 Diabetes secondary to improved diabetes care?
In an epidemiologic study by Secrest, Becker, Kelsey, LaPorte, and Orchard (All-Cause Mortality Trends in a Large Population-Based Cohort With Long-Standing Childhood-Onset Type 1 Diabetes) that will be published in the December issue of Diabetes Care (Volume 33, number 12), the authors attempted to answer this important question in regard to mortality. (This paper is the largest U.S. population based type 1 diabetes cohort with at least 25 years of follow-up.)
After the discovery of insulin in the early 1920s, the next big leap was in the 1980s and 1990s wherein the development of blood glucose monitoring become a reality (colorimetric blood glucose strips: Chemstrips ®, blood glucose meters), along with A1c testing. The first insulin pump (it was huge and carried on the back by the researcher) was invented and further modified. Insulin pump therapy gained enormous traction in the late 1990s and early 21st century and has become one of the most popular forms of insulin therapy. However, despite these major advances to diabetes care, type 1 diabetes complications often lead to earlier mortality.
The authors of this paper compiled the information for their study on a large population based cohort in Pittsburgh, Pennsylvania (Allegheny County) that were diagnosed with type 1 diabetes between 1965 and 1979. The mortality trends were studied between 28 and 43 years of follow-up after diagnosis. The differences of mortality rates were noted by sex, race (Caucasian vs. African American), and year of type 1 diagnosis. It is important to note that the key strengths of this study include the size of the population based cohort (1075 individuals) and the excellent follow-up after 25 years.
What were the conclusions?
- With duration of 28 to 43 years of type 1 diabetes, the risk of dying is seven times higher than that of the local general population, with a significant improvement of standardized mortality ratios for those with diabetes diagnosed most recently in this group of individuals.
- Compared with respective general populations, women with type 1 diabetes had standardized mortality rates nearly three times higher than that of men with type 1 diabetes. (The authors hypothesize that this result may reflect the much lower mortality rates for younger women in the general population.) It is to be noted that long term mortality rates do NOT differ by sex in type 1 diabetes in the authors previous epidemiologic data, but do differ from the findings in New Zealand, Norway, and the UK. For more information see details in the article.
- Although race is a significant predictor of mortality within the Pittsburgh cohort, no differences of standardized mortality rates were seen by race. (The authors hypothesize that this result can be explained by the extremely high mortality rates observed in young African Americans in the general population resulting from violent deaths. Therefore, although mortality rates in T1DM are 2 to 3 times higher in African Americans, it was felt by the authors that this excess can be attributed to the background African American mortality rates and not to their diabetes).
- Temporal improvements in mortality were noted in this study and also have been reported in other type 1 epidemiologic diabetes studies. Onset mortality (death within the first year of diagnosis) improved most in the cohort diagnosed between 1975 and 1979.
The results are encouraging, especially for individuals diagnosed more recently. However, based on the statistics in this paper, those with diabetes diagnosed between 1975 and 1979 (most recent in the study), still die at rates 5 times higher than that of the general population. It appears that even further efforts will be required to improve care in women and African Americans with Type 1 diabetes. My assumption is that future research will start to specifically target these groups in an attempt to improve racial/sex cohort-specific care.