Association of 25‐hydroxyvitamin D with type 2 diabetes among patients undergoing coronary angiography: cross‐sectional findings from the LU dwigshafen R isk and C ardiovascular H ealth ( LURIC ) S tudy

Summary Objective Evidence suggests that vitamin D may protect against the onset of diabetes. However, the mechanisms underlying the role of vitamin D on glycaemic status are unclear and warrant further investigation. We sought to determine the relationship between serum 25‐hydroxyvitamin D (25[ OH ] D ) and glycaemic status among intermediate‐to‐high‐risk patients scheduled for coronary angiography. Methods Participants were 3316 male and female patients (mean ± SD age, 62·7 ± 10·6 years). Four categories were formed according to serum 25[ OH ] D levels. The association between serum 25[ OH ] D and diabetes was assessed using multivariable logistic regression. Results Fasting and 2 h post‐load glucose, HbA1c and the HOMA ‐ IR indices diminished with increasing serum 25[ OH ] D levels ( P  < 0·001). However, no associations were observed between insulin, pro‐insulin or C ‐peptide and serum 25[ OH ] D concentrations. The pro‐inflammatory markers IL ‐6 and hs‐ CRP also decreased considerably with higher vitamin D levels ( P  < 0·001). After full adjustment, those with optimal serum 25[ OH ]D levels had a reduced odds for fasting diabetes ( OR  = 0·63; 95% CI , 0·46–0·86; P trend  = 0·01), 2 h post‐load diabetes ( OR  = 0·46; 95% CI , 0·29–0·74; P trend  = 0·004), both fasting/2 h post‐load diabetes ( OR  = 0·61; 95% CI , 0·42–0·87; P trend  = 0·001) and all of the combined hyperglycaemic states ( OR  = 0·68; 95% CI , 0·52–0·80; P trend  = 0·01). Conclusions Higher serum 25[ OH ]D levels were associated with better glycaemic status and lower inflammation. Should these observations be confirmed in future studies, vitamin D supplementation may prove a useful adjunct in attenuating the onset of diabetes.