Osteocalcin levels are inversely associated with Hba1c and BMI in adult subjects with long-standing type 1 diabetes

Purpose Diabetic osteopathy is an upcoming complication of diabetes characterized by osteoporosis, increased risk for bone fractures and alterations in bone metabolism. Osteocalcin (OC) is a bone-specific protein produced by osteoblasts involved in the regulation of glucose and energy metabolism. The aim of this study is to determine whether OC serum levels are correlated with metabolic control in adult subjects with type one diabetes mellitus (T1DM). Methods A cross-sectional study was conducted on 93 subjects (51 men) with mean age, disease duration and body mass index (BMI) of 39.9 +/- 12.3, 17.2 +/- 12.6 years and 24.5 +/- 3.4 kg/m(2), respectively. Blood samples were drawn to measure levels of hemoglobin A1c (HbA1c), OC, 25-OH vitamin D and PTH. Results Significant inverse correlations were found between OC and HbA1c (r = -0.295, P = 0.004) and between OC and BMI (r = -0.218, P = 0.037). These correlations were confirmed also among men in the analyses by gender [HbA1c vs OC: r = -0.363, P = 0.009; BMI vs OC: r = -0.291, P = 0.043], and similar but nonsignificant trends were confirmed among women. A significant difference in mean OC was also found between the lowest and the highest HbA1c tertile (22.3 +/- 10.0 vs 16.9 +/- 8.0 ng/mL, P = 0.025). Conclusions These data show that in T1DM of long duration, OC serum levels are inversely associated with HbA1c and BMI, supporting the hypothesis that a poor glycemic control can affect osteoblast function.