Late adulthood mortality among African-American and white American people with Type 1 diabetes according to age at diabetes diagnosis

Abstract

Aims: To estimate the overall and cause-specific mortality in a population of African-Americans and white Americans with a low socio-economic status who had young-onset insulin-treated diabetes and had survived beyond the age of 40 years, and to examine whether any excess risk varied according to age at diabetes onset.

Methods: Using the Southern Community Cohort Study, we conducted a mortality follow-up of a cohort of mostly low-income participants aged 40-79 years (mean 50 years) at cohort entry with insulin-treated diabetes diagnosed before age 30 years (n=475) and without diabetes (n=62 266). Childhood onset was defined as diabetes diagnosed before age 20 years (n=162), while young-adulthood onset was defined as diabetes diagnosed between ages 20 and 29 years (n=313). Cause-specific mortality was based on both underlying and contributing causes of death, obtained from death certificates. Multivariable Cox analysis was performed.

Results: During follow-up (mean 9.5 years), 38.7% of those with and 12.9% of those without diabetes died. Compared with those without diabetes, increases in mortality rate were generally similar among those with childhood- and young-adulthood-onset diabetes for deaths from: all causes (childhood: hazard ratio 4.3, CI 3.3-5.5; young adulthood: hazard ratio 4.9, CI 4.0-5.8); ischaemic heart disease (childhood: hazard ratio 5.7, CI 3.5-9.4; young adulthood: hazard ratio 7.9, CI 5.6-11.0); heart failure (childhood: hazard ratio 7.3, CI 4.2-12.7; young adulthood: hazard ratio 5.4, CI 3.3-8.9); sepsis (childhood: hazard ratio 10.3, CI 6.1-17.3; young adulthood: hazard ratio 8.8, CI 5.7-13.5); renal failure (childhood: hazard ratio 15.1, CI 8.6-26.5; young adulthood: hazard ratio 18.2, CI 12.3-27.1); respiratory disorders (childhood: hazard ratio 3.9, CI 2.3-6.7; young adulthood: hazard ratio 5.3, CI 3.7-7.7); suicide/homicide/accidents (childhood: hazard ratio 2.3, CI 0.72-7.0; young adulthood: hazard ratio 5.8, CI 3.4-10.2); and cancer (childhood: hazard ratio 2.1, CI 0.98-4.4; young adulthood: hazard ratio 1.2, CI 0.55-2.5).

Conclusions: We observed high excess long-term mortality for all-cause, renal failure, ischemic heart disease and heart failure mortality in African-American and white American people with early-onset insulin-treated diabetes.

FIGURE 1

Contribution to mortality of each of the major contributing causes of death in Type 1 diabetes. Mortality event numbers by diabetes onset were as follows: ischaemic heart disease: childhood onset n=17, young adulthood onset n=36, no diabetes n=1380; heart failure: childhood onset n=13, young adulthhood onset n=16, no diabetes n=843; renal disease: childhood onset n=14, young adulthood onset n=29, no diabetes n=438; sepsis: childhood onset n=17, young adulthood onset n=22, no diabetes n=841; respiratory disorders: childhood onset n=13, young adulthood onset n=29, no diabetes n=2053; cancer: childhood onset n=7, young adulthood onset n=7, no diabetes n=2569; accidents: childhood onset n=3, young adulthood onset n=15, no diabetes n=871.

FIGURE 2

Multivariable adjusted risk of all-cause and cause-specific mortality for Type 1 diabetes compared with those without diabetes, odds ratio (OR) and 95% CI. Solid black lines= childhood onset Type 1 diabetes. Dashed lines = young-adulthood-onset Type 1 diabetes. Multivariable analyses additionally controlled for sex, race, hypercholesterolaemia, hypertension, prior ischaemic heart disease, prior stroke/transient ichaemic attack, history of smoking, education, annual household income and health insurance coverage.

FIGURE 3

Multivariable adjusted risk of all-cause and cause-specific mortality for Type 1 diabetes compared with those without diabetes stratified by race, odds ratio (OR) and 95% CI. Solid black lines= childhood-onset Type 1 diabetes. Dashed lines = young-adulthood-onset Type 1 diabetes. Multivariable analyses additionally controlled for sex, hypercholesterolaemia, hypertension, prior ischaemic heart disease, prior stroke/transient ischaemic attack, history of smoking, education, annual household income and health insurance coverage. P value for race × age at diabetes diagnosis interaction term=0.005 for renal disease mortality. P value for race × age at diabetes diagnosis interaction term=0.007 for cancer mortality. AA, xxx; EA,.