CRP and diabetes mellitus: Melatonin level was negatively correlated with age (r = −0.202; P = 0.001), diabetes duration (r = −0.282; P < 0.001), serum HbA1c (r = −0.195; P = 0.002), hs-CRP (r = −0.324; P < 0.001), and TSH (r = −0.184; P = 0.004) levels and positively correlated with MoCA score, serum HDL-C (r = 0.145; P < 0.001), FT3 (r = 0.241; P < 0.001), and FT4 (r = 0.169; P = 0.008) levels.