Higher A1c has been associated with an increased risk of CVD but the role of social determinants of health is poorly described. We examined the association of A1c with incident CVD and whether this varied by residential segregation. This case-cohort study included 2,273 participants from a stratified random sample at baseline (2003-2007) and 1,927 participants with incident CVD, both free of CVD at baseline (mean age 65.7 ± 10.6; 48% African American; 52% female; 17.7% with diabetes). During a median follow-up of 7.7 years., there were 171 strokes and 195 CHD events adjudicated among those with diabetes; 504 strokes and 494 CHD events adjudicated among those without diabetes. Cox proportional hazards models were used to examine the association between higher baseline A1c and time to incident CVD. Models sequentially adjusted for demographics, risk factors (BP, cholesterol, smoking, BMI), individual socioeconomic status (education; income), and tract-level residential segregation indices derived from census data (dissimilarity index, interaction index, isolation index). Additional models included two-way interactions of A1c with each residential segregation index. Higher A1c was associated with an increased risk of CVD [HR = 1.20 (95% CI: 1.06-1.37) per 1 unit increase in A1c] among those with diabetes in the fully adjusted model. However, there was no association among those without diabetes [HR = 0.94 (95% CI: 0.77-1.16)]. Two-way interactions with A1c were significant (p for interaction) for each residential segregation index for those with diabetes: dissimilarity index (p=0.01), interaction index (p=0.04), and isolation index (p=0.02). However, only the A1c and interaction index was significant among those without diabetes. Residential segregation may impact the relationship of higher A1c with risk for incident CVD; this association may be stronger among diabetic individuals with greater residential segregation.
D.M. Cummings: None. S.P. Patil: Research Support; Self; Novo Nordisk Inc. D. Long: None. A.P. Carson: Research Support; Self; Amgen Inc. A. Cherrington: None. M. Safford: None. S. Judd: None. V.J. Howard: None. G. Howard: None.
National Institutes of Health