Association between serum 25( OH )D 3 and cardiovascular morbidity and mortality in people with Type 2 diabetes: a community‐based cohort study

Aim We aimed to explore the association between vitamin D and cardiovascular morbidity and mortality in people with Type 2 diabetes recruited from a community‐based study because there is limited and inconsistent research of this group. Methods A prospective community‐based cohort study among people aged 55–66 years with Type 2 diabetes as part of The Cardiovascular Risk in Type 2 Diabetes – A Prospective Study in Primary Care ( CARDIPP ). We analysed serum 25‐hydroxyvitamin D 3 [25( OH )D 3 ] at baseline. Cox regression analyses were used to calculate hazard ratios ( HR ) for the first myocardial infarction, stroke or cardiovascular mortality according to 25( OH )D 3 . Results We examined 698 people with a mean follow‐up of 7.3 years. Serum 25( OH )D 3 was inversely associated with the risk of cardiovascular morbidity and mortality: HR 0.98 [95% confidence interval ( CI ) 0.96 to 0.99, P = 0.001]. Compared with the fourth quartile (Q4) [25( OH )D 3 > 61.8 nmol/l], HR (with 95% CI ) was 3.46 (1.60 to 7.47) in Q1 [25( OH )D 3 < 35.5 nmol/l] ( P = 0.002); 2.26 (1.01 to 5.06) in Q2 [25( OH )D 3 35.5–47.5 nmol/l] ( P = 0.047); and 1.62 (0.70 to 3.76) in Q3 [25( OH )D 3 47.5–61.8 nmol/l] ( P = 0.26) when adjusting for age, sex and season. The results remained significant after adjusting also for cardiovascular risk factors, physiological variables including parathyroid hormone and previous cardiovascular disease ( P = 0.027). Conclusions Low 25( OH )D 3 is associated with an increased risk of cardiovascular morbidity and mortality in people with Type 2 diabetes independent of parathyroid hormone. Vitamin D could be considered as a prognostic factor. Future studies are needed to explore whether vitamin D deficiency is a modifiable risk factor in Type 2 diabetes.