FNDC5 and type 2 diabetes mellitus: Importantly, the serum levels of procollagen type 1 intact N-terminal propeptide (P1NP), osteocalcin (OC), and irisin were notably lower in T2DM subjects than in NGT ones (36.42 (25.68,51.70) vs. 44.52 (35.73,58.05) ng/ml, P < 0.05; 16.15 (12.40,21.66) vs. 18.70 (15.56, 23.22) ng/ml, P < 0.05; 10.90 ± 1.88 vs .11.69 ± 2.06 ng/mL,P < 0.05).