Insulin resistance, metabolic syndrome, and blood pressure progression among Blacks: the Jackson Heart Study

OBJECTIVE: There is a paucity of data on the relations of insulin resistance with incident blood pressure (BP) changes among Blacks. We investigated the associations of insulin resistance and metabolic syndrome (MetS) with BP progression in a community-based sample of African Americans. METHODS: We analyzed 1064 participants without hypertension at baseline (2000-2004) who attended at least one follow-up visit in 2005-2008 or 2009-2013. Four insulin resistance indices [fasting insulin, insulin-to-glucose ratio (IGR), homeostasis model assessment of insulin resistance (HOMA-IR), and quantitative insulin sensitivity check index (QUICKI)] and MetS (excluding hypertension in the definition) were assessed at baseline. Robust Poisson regression was used to generate risk ratios (RRs) and 95% confidence intervals (CI) for BP progression and incident hypertension. RESULTS: Over a median of 7 years, 69.6% progressed to a higher BP category and 62.7% developed hypertension. After multivariable adjustment, participants in the highest quartile of HOMA-IR had higher risks of BP progression [RR 1.25 (95% CI 1.09-1.43), Ptrend = 0.004] and hypertension [RR 1.35 (95% CI 1.16-1.58), Ptrend < 0.001] compared with those in the lowest quartile. A similar positive association of insulin resistance with BP outcomes was noted with insulin resistance assessed using IGR, fasting insulin, and QUICKI. MetS was associated with increased risks of BP progression [RR 1.15 (95% CI 1.02-1.30), P = 0.02] and incident hypertension [RR 1.23 [95% CI 1.08-1.41], P = 0.002]. These associations were present across baseline BP categories. CONCLUSION: Our findings support the notion that higher insulin resistance levels are associated with greater risks of BP progression and incident hypertension among Blacks.