Uncarboxylated Osteocalcin Levels in Patients With Metabolic Syndrome and Their Association With Metabolic Parameters

Background: Uncarboxylated osteocalcin (uOCN) synthesized by osteoblasts was shown to increase insulin secretion and peripheral insulin sensitivity in pancreatic islets. The present study evaluated the uOCN levels and its association with metabolic parameters in non-diabetic patients with metabolic syndrome (MetS) to test our hypothesis that uOCN levels may be lower in MetS, which is characterized by insulin resistance. Methods: The study included 30 patients with MetS aged 18 years and above (13 male, 17 female, mean age 39.00 +/- 5.09 years) and 30 healthy controls (15 male, 15 female, mean age 36.23 +/- 6.71 years). Diabetics and post-menopausal women were excluded. The International Diabetes Federation criteria were used to define MetS. Groups were compared depending on their uOCN levels, and association of uOCN with metabolic parameters was assessed. Results: Serum u0CN levels were 5.56 +/- 3.36 ng/mL in patients with MetS whereas they were 6.26 +/- 2.65 ng/mL in healthy controls (P = 0.183). Serum uOCN levels showed a negative correlation with HbA1c and body mass index (r =-0.308, P = 0.017; r =-0.278, P = 0.032, respectively) in all patients, and with waist circumference (r =-0.190, P = 0.032; r =-0.379, P: 0.047, respectively) in males. Conclusions: Although the difference in uOCN levels between patients with MetS and control group was not statistically significant, a negative correlation of uOCN with HbA1c, body mass index and waist circumference may provide support to our hypothesis that uOCN levels may be lower in MetS.