Aims/hypothesis: Ideal cardiovascular health (ICH) is associated with lower risk of incident diabetes, but whether this association varies by baseline glycemia (normal [<100 mg/dL] vs. impaired fasting glucose [100-125 mg/dL]) remains to be clarified. We assessed the incidence of diabetes based on American Heart Association (AHA) ICH components stratified by glycemic status to determine whether ICH is more effective for primordial or primary prevention of diabetes among middle-aged and older adults.
Methods: This study included 7,662 non-Hispanic whites and African Americans from the REasons for Geographic and Racial Differences in Stroke (REGARDS) Study without prevalent diabetes at baseline (2003-2006), who completed the follow-up exam (2013-2016). Participants were categorized as having ideal, intermediate or poor cardiovascular health, as defined by the AHA 2020 Impact Goals, based on baseline ICH components (total cholesterol, blood pressure, dietary intake, tobacco use, physical activity and body-mass index (BMI)). We categorized participants based on their total number of components that were ideal (0-1 “poor”, 2-3 “intermediate”, and 4+ “ideal”). Incident rate ratios (IRR) were calculated using modified poisson regression adjusting for age, sex, education, income, race, alcohol use, estimated glomerular filtration rate, urine albumin:creatinine ratio and high-sensitivity C-reactive protein. After confirming significant interactions with multiplicative interaction terms and application of likelihood ratio test, we stratified by glycemic status (normal vs. impaired fasting glucose).
Results: Among REGARDS participants (mean age 63.0 [SD 8.4] years, 56% female, 26% African American), there were 560 incident diabetes cases (median follow-up 9.5 years). Overall, those with 2-3 and 4+ ICH components vs. 0-1 components had 31% (IRR 0.69; 95% CI 0.61, 0.79) and 71% lower (IRR 0.29; 95% CI 0.20, 0.42) risk of diabetes, respectively. Among 5,930 participants with normal fasting glucose, these risks were 36% (IRR 0.64; 95% CI 0.52, 0.79) and 80% lower (IRR 0.20; 95% CI 0.10, 0.37), while among 1,732 participants with baseline impaired fasting glucose these risks were 8% (IRR 0.92; 95% CI 0.80,1.07) and 13% lower (IRR 0.87; 95% CI 0.58,1.30) (p for interaction by baseline glucose status <0.0001).
Conclusions/interpretation: Meeting an increasing number of ideal levels of dietary intake, physical activity, smoking, blood pressure, cholesterol and BMI was associated with a dose-dependent lower risk of diabetes for individuals with normal fasting glucose but not impaired fasting glucose. This suggests the AHA 2020 guidelines may be more effective for primordial versus primary prevention of diabetes among middle-aged and older adults.