Relationships between Adiponectin, Osteocalcin and Insulin Resistance in Obese Egyptian Individuals: A Link between Skeleton, Obesity and Insulin Resistance

Background: Scientific interest has focused on the association between osteocalcin, ( which originates from the skeletal system) and glucose metabolism. Although the association between lipid metabolism, adiponectin, and metabolic syndrome is well known, that between obesity, insulin resistance, and osteocalcin has not been clarified yet. Aim of the work: assessment of insulin resistance in Egyptian obese persons, and to identify whether or not there is a difference between patients with or without metabolic syndrome in respect to osteocalcin and adiponectin levels and the relation of both cytokines to different parameters of metabolic syndrome. Patients and methods: This study was done at Al-Azhar University Hospital (New Damietta), Internal Medicine Department, in the period from February 2014, to October 2014, sixty obese patients (31 male and 29 female), with criteria of metabolic syndrome (group I); and thirty obese persons (16 male and 14 female) without criteria of metabolic syndrome (Group II) and thirty normal healthy volunteers (17 male and 13 female) (Control group). Patients and controls were submitted to full history taking; thorough clinical examination, waist circumference (WC), and BMI were calculated. Laboratory investigations included (serum adiponectin; serum osteocalcin; lipid profile; fasting & postprandial blood sugar, fasting insulin and HOMA-IR) were calculated. Results: When comparing metabolic syndrome group with control group, there was a statistically significant difference in all studied variables except for total bilirubin and creatinine. In metabolic syndrome group, there was a statistically significant increase of adiponectin in males when compared to females; but osteocalcin and HOMA-IR had no statistically significant difference. In obese group, there was only significant increase of osteocalcin in males when compared to females. In addition, among metabolic group; morbid obese patients had statistically significantly decreased levels of adiponectin and triglycerides when compared to mild to moderate obese patients. There was negative, mild, statistically significant correlation between uric acid and osteocalcin. And there was positive, moderate, significant correlation between adiponectin and height; while there was negative, moderate, significant correlation between adiponectin and BMI. On the other hand, in obese group; there was significant, moderate, positive correlation between osteocalcin and each of albumin and ESR; but no statistically significant correlation between adiponectin and any other variables in this group. Conclusion: Serum levels of adiponectin and osteocalcin were decreased in subjects with metabolic syndrome as well as obese subjects without criteria of metabolic syndrome. In addition, serum adiponectin and serum osteocalcin were negatively correlated with parameters of metabolic syndrome. The association of osteocalcin and adiponectin with the metabolic syndrome and atherosclerosis supports the reciprocal regulation of bone on energy metabolism, implicating that osteocalcin and adiponectin might be a new therapeutic target for the treatment of metabolic syndrome and obesity and even the associated cardiovascular complications.