SPP1 and type 2 diabetes mellitus: In addition, increased OPN serum levels are significantly correlated with HbA1c, FINS (mUI/mL), and HOMA-IR and cytokines IL-6, IL-8, IL-18, IL-1β, TNF-α, and serum CRP levels, respectively, in T2D patients with poor compared to that of moderate glycemic control status.