Low total osteocalcin levels are associated with all-cause and cardiovascular mortality among patients with type 2 diabetes: a real-world study

Abstract

Abstract Background The association between osteocalcin and mortality has been scantly studied. We aimed to investigate the association between osteocalcin along with its trajectories and mortality based on long-term longitudinal data. Methods We performed a retrospective cohort study of 9413 type 2 diabetic patients with at least three measurements of total serum osteocalcin within 3 years since their first inpatient diagnosis of type 2 diabetes. Baseline, mean values of osteocalcin levels and their trajectories were used as exposures. A multivariable-adjusted Cox proportional hazards model was used to estimate the association of osteocalcin levels and their trajectories with mortality. Results During a mean follow-up of 5.37 years, 1638 patients died, of whom 588 were due to cardiovascular events. Multivariable-adjusted hazard ratios (HRs) across quintiles of baseline osteocalcin levels were 2.88 (95% confidence interval (CI) 2.42–3.42), 1.65 (95% CI 1.37–1.99), 1.17 (95% CI 0.96–1.42), 1.00, and 1.92 (95% CI 1.60–2.30) for all-cause mortality, and 3.52 (95% CI 2.63–4.71), 2.00 (95% CI 1.46–2.73), 1.03 (95% CI 0.72–1.47), 1.00, 1.67 (95% CI 1.21–2.31) for CVD mortality, respectively. When we used the mean values of osteocalcin as the exposure, U-shaped associations were also found. These U-shaped associations were consistent among patients of different baseline characteristics. Patients with a stable or even increasing trajectory of osteocalcin may have a lower risk of both all-cause and CVD mortality. Conclusions A U-shape association between baseline osteocalcin and mortality was observed among patients with type 2 diabetes. Patients with lower levels of serum osteocalcin during follow-ups had higher risks for all-cause and cardiovascular mortality.