Role of adiponectin in mediating the association of osteocalcin with insulin resistance and type 2 diabetes: a cross sectional study in pre- and post-menopausal women.

OBJECTIVE: To analyse the association of osteocalcin with insulin resistance and type 2 diabetes and assess the role of adiponectin in these relationships. METHODS: This study comprised 98 newly diagnosed type 2 diabetic women (51 pre-menopausal and 47 post-menopausal) and 102 age and BMI matched controls (53 pre-menopausal and 49 post-menopausal). Insulin resistance was calculated by homeostasis model assessment-insulin resistance (HOMA-IR). RESULTS: Osteocalcin was significantly positively correlated with adiponectin in both pre-menopausal (p = 0.0026) and post-menopausal diabetic women (p = 0.0357). Significant negative association between osteocalcin and HOMA-IR was observed only in pre-menopausal diabetic women (p = 0.0019), but the association was partially reduced (p = 0.0219) after additional adjustment for adiponectin. Adiponectin slightly attenuated the inverse association between osteocalcin and presence of type 2 diabetes in both pre- and post-menopausal women. CONCLUSION: The protective action of osteocalcin against the development of insulin resistance and type 2 diabetes in women may be partially mediated through up-regulation of adiponectin secretion.

Relationship of serum osteocalcin levels with blood glucose, insulin resistance and lipid profile in central Indian men with type 2 diabetes.

OBJECTIVE: To assess the relationship of serum osteocalcin levels with blood glucose, insulin resistance and lipid profile in central Indian men with type 2 diabetes. METHODS: Anthropometric and biochemical parameters were measured in 56 newly diagnosed type 2 diabetic men and in 56 age and body mass index (BMI) matched controls. Insulin resistance was calculated by homeostasis model assessment of insulin resistance (HOMA-IR). RESULTS: After adjustment for age and BMI, osteocalcin levels were negatively correlated with fasting plasma glucose (p = 0.0004), fasting insulin (p = 0.0311), HOMA-IR (p = 0.0023), and triglycerides (p = 0.0095), and positively correlated with high density lipoprotein (HDL)-cholesterol (p = 0.0042) in type 2 diabetic patients. In multivariate logistic regression analyses that adjusted for age, BMI, waist circumference and waist-to-hip ratio, osteocalcin was inversely associated with the presence of type 2 diabetes (p < 0.0001). CONCLUSION: Osteocalcin may play a protective role in the pathogenesis of type 2 diabetes, not only through direct involvement in glucose homeostasis, but also through improving lipid profile.