Introduction: Diabetes and insulin resistance are major contributors to atherosclerotic cardiovascular disease (ASCVD) risk, but the lifetime risks (LTR) associated with normoglycemia, impaired fasting glucose (IFG), and diabetes (DM) in middle-aged adults have not been reported.
Hypothesis: Higher fasting glucose (FG) category will be associated with a monotonic increase in the LTR for ASCVD.
Methods: We pooled data from 7 observational cohorts of US black and white men and women followed from 1960 through 2015. Categories of FG were normoglycemia (<100 mg/dl), IFG (100-125 mg/dl), and DM (≥126 mg/dl or use of DM medications). ASCVD was defined as fatal and nonfatal coronary heart disease (CHD) and fatal and nonfatal stroke. Individuals were free of symptomatic ASCVD at index age 55 years. LTR for incident ASCVD after age 55 was estimated according to FG category using a modified Kaplan-Meier survival analysis, adjusted for the competing risk of non-ASCVD death.
Results: Our sample included 19630 individuals (6197 blacks, 11015 women) without a prior ASCVD event. Mean baseline FG level was 90.1 mg/dl for normoglycemics, 107.4 mg/dl for IFG, and 176.6 mg/dl for DM. Greater age, body mass index, blood pressure, and male sex and black race were associated with increasing FG category. LTR for ASCVD through age 85 among women was 15.5% for normoglycemics, 16.4% for IFG, and 38.6% for DM (Figure 1A). Among men, LTR for ASCVD through age 85 was 22.2% for normoglycemia, 25.0% for IFG, and 47.7% for DM (Figure 1B). The difference in LTR for ASCVD between normoglycemics and IFG was not statistically significant for women (LTR difference 95% confidence interval (CI): -3.8, 2.0) or men (LTR difference 95% CI: -5.8, 0.2).
Conclusion: LTRs for ASCVD were similar among normoglycemia and IFG categories. However, LTR among middle-aged participants with DM were 39-48%; approximately twice as high as those with IFG. These data strongly support the importance of public health and clinical strategies that target prevention of incident DM by midlife.