CRP and diabetes mellitus: Association between 25-hydroxyvitamin (OH)D3, 24,25-dihydroxyvitamin (OH)2D3, and vitamin D metabolite ratio (VMR) with C-reactive protein (CRP), interleukin (IL)-8, fructosamine, and phagocytic function of Escherichia coli in 40 dogs that were either non-diabetic healthy controls (n = 20) or dogs with naturally occurring diabetes mellitus (n = 20).