BACKGROUND:
Few studies have examined the relationship between vitamin D levels and incident cardiovascular events in large well-characterized type 2 diabetes cohorts.
METHODS:
We performed prospective analyses to determine associations between vitamin D status and vascular endpoints among 936 Veterans Affairs Diabetes Trial (VADT) participants (mean age 59.7 years; 96.7% male; 40.4% minority). 25 (OH)-vitamin D was measured a median of two years after entry into the VADT study and participants were subsequently followed an average of 3.7 years for outcomes. Cox proportional hazard models were used to calculate hazard ratios (HRs) for macrovascular endpoints in relation to vitamin D quartile. The primary composite endpoint included documented myocardial infarction; stroke; death from cardiovascular causes; new or worsening congestive heart failure; surgical intervention for cardiac, cerebrovascular, or peripheral vascular disease; inoperable coronary artery disease; and amputation for ischemic gangrene.
RESULTS:
On average VADT participants had high cardiovascular risk at entry into the study: 65.3% of the patients recruited were obese, 38.5% had previously had a vascular event, 78.7% had hypertension and 59.5% were using statins. During follow-up, 17.2%, 5.0%, 5.9%, 2.4% and 6.6% of participants had a primary composite endpoint, myocardial infarction, chronic heart failure, cardiovascular death or all-cause death, respectively. After adjusting for age, minority status, treatment arm and history of prior event, individuals in the lowest quartile of vitamin D (i.e., 1 to 15.9 ng/ml) were at similar risk of the primary composite endpoint [HR=1.26 (95% CI: 0.81, 1.96)], myocardial infarction [HR=1.13 (95% CI: 0.53, 2.42)], congestive heart failure [HR=1.44 (95% CI: 0.67, 3.06)], cardiovascular death [HR=0.86 (95% CI: 0.28, 2.63)], and death from any cause [HR=1.04 (95% CI: 0.53, 2.04)] as individuals in the highest quartile of vitamin D (i.e., 29.9 to 77.2 ng/ml).
CONCLUSIONS:
These data indicate that vitamin D status had no significant impact on the incidence of macrovascular events in a cohort of high-risk veterans with type 2 diabetes mellitus in which traditional risk factors were managed according to current treatment guidelines.
SUPPORT:
This work was supported by American Heart Association Grant-in-Aid AHA0755466U and the Research Service of the Charleston SC VA Medical Center.
Vitamin D status and the risk of type 2 diabetes: The Melbourne Collaborative Cohort Study
