Impact of Osteocalcin on Glycemic Regulation and Insulin Sensitivity in Type 2 Diabetes Mellitus Patients

Background Type 2 diabetes mellitus (T2DM) is a worldwide health issue impacting millions of individuals. In recent years, bone has been identified as an endocrine organ that regulates glucose metabolism by the release of osteocalcin, an osteoblast-specific hormone, which affects fat accumulation and blood glucose levels. Osteocalcin has been associated with insulin sensitivity and glucose control. Objective The study investigates the relationship between circulating osteocalcin levels with glycemic control parameters and insulin resistance in T2DM patients. Methods A total of 234 subjects were recruited, including T2DM patients (n=117) and age-sex-matched controls (n=117). Fasting blood samples were collected to measure fasting blood sugar (FBS), insulin, glycated hemoglobin (HbA1c), and osteocalcin levels. Osteocalcin levels were determined using an enzyme-linked immunosorbent assay. Insulin resistance was calculated using the Homeostatic Model Assessment for Insulin Resistance (HOMA-IR). Results The levels of osteocalcin in T2DM patients were significantly lower (7.07 ± 3.80 ng/mL) than in healthy controls (20.41 ± 13.50 ng/mL, p<0.0001). A significant negative correlation was observed between osteocalcin and HbA1c (r=-0.710, p<0.01), as well as between osteocalcin and FBS (r=-0.676, p<0.01). T2DM patients also showed significantly higher insulin resistance, as evidenced by their elevated HOMA-IR scores (4.39 ± 1.95 vs. 3.62 ± 1.82, p=0.002). There was a negative correlation between osteocalcin and HOMA-IR (r=-0.324, p=0.0001). Conclusion This study shows that osteocalcin levels are significantly reduced in patients with T2DM and demonstrate a negative correlation with HbA1c, FBS, and insulin resistance.