CYP27A1 and diabetes mellitus: For patients with diabetes, eGFR was negatively correlated with osteocalcin (OC) (r = −0.434, P < 0.05), procollagen type 1 intact N-terminal propeptide (P1NP) (r = −0.350, P < 0.05), and β-carboxy-terminal cross-linking telopeptide of type I collagen (β-CTX) (r = −0.179, P < 0.05) levels.