Serum osteocalcin in subjects with metabolic syndrome and central obesity

AIMS: The aim of this study was to determine if osteocalcin is related to adiposity and hyperglycaemia in metabolic syndrome irrespective of the presence of diabetes mellitus.
MATERIALS AND METHODS: This was a cross sectional study of 90 patients (59 men and 31 women) with metabolic syndrome as defined by the International Diabetes Federation criteria. Based on medical history 50 out of 90 patients had a diabetes. Anthropometric data were collected and blood taken for measurement of osteocalcin, fasting lipids, fasting glucose and insulin resistance (using homeostatic model assessment index, HOMA-IR).
RESULTS: Osteocalcin correlated negatively with fasting glucose (r=-0.366, p<0.001) and HOMA-IR (r=-0.305, p<0.05) but not with waist circumference (r=0.079), body mass index (r=0.028), total cholesterol (r=0.061) or triglycerides (r=0.009). Diabetics had higher HOMA-IR (p<0.01) and lower osteocalcin levels (p<0.01) than non-diabetics. Among diabetics, osteocalcin correlated with glucose only (r=-0.341, p=0.015). In non-diabetics, osteocalcin correlated with HOMA-IR (r=-0.359, p=0.023) via insulin (r=-0.402, p=0.010). Patients with impaired fasting glucose levels (5.6-6.9mmol/L) had the same HOMA-IR as diabetics (p=0.076) but not low osteocalcin (p=0.025).
CONCLUSIONS: In this cross-sectional study of subjects with metabolic syndrome and central obesity, low osteocalcin was associated with diabetes but not adiposity.
KEYWORDS: Adiposity; Central obesity; Diabetes; Metabolic syndrome; Osteocalcin