Diabetes and the risk of cardiovascular events and all-cause mortality among older adults: an individual participant data analysis of five prospective studies.

Background: Guidelines and studies provide conflicting information on whether type 2 diabetes (T2D) should be considered a coronary heart disease risk (CHD) equivalent in older adults.

Methods: We synthesized participant-level data on 82,723 individuals aged ≥65 years from five prospective studies in two-stage meta-analyses. We estimated multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) of T2D (presence versus absence) on a primary composite outcome defined as cardiovascular events or all-cause mortality. Secondary outcomes were the components of the composite. We evaluated CHD risk equivalence by comparing outcomes between individuals with T2D but no CHD versus CHD but no T2D.

Results: The median age of participants was 71 years, 20% had T2D and 17% had CHD at baseline. A total of 29,474 participants (36%) experienced the composite outcome. Baseline T2D was associated with higher risk of cardiovascular events or all-cause mortality versus no T2D (HR 1.44, 95% CI [1.40-1.49]). The association was weaker in individuals aged ≥75 years versus 65-74 years (HR 1.32 [1.19-1.46] vs. 1.56 [1.50-1.62]; p-value for interaction = .032). Compared to individuals with CHD but no T2D, individuals with T2D but no CHD had a similar risk of the composite outcome (HR 0.95 [0.85-1.07]), but a lower risk of cardiovascular events (HR 0.76 [0.59-0.98]).

Conclusions: T2D was associated with increased risk of cardiovascular events and all-cause mortality in older adults, but T2D without CHD conferred lower risk of cardiovascular events compared to CHD without T2D. Our results suggest that T2D should not be considered a CHD risk equivalent in older adults.