Objective: Osteocalcin has been reported to influence insulin secretion in experimental animals. We investigated whether serum osteocalcin was associated with measures of insulin resistance, circulating adipokine levels, and the presence of metabolic syndrome (MetSyn).
Methods and results: Serum osteocalcin was measured by solid-phase sandwich immunoassay in 1284 blacks (64+/-9 years; 71% women) and 1209 non-Hispanic whites (59+/-10 years; 57% women) belonging to hypertensive sibships. MetSyn was defined per Adult Treatment Panel III criteria. The prevalence of MetSyn was 50% in blacks and 49% in non-Hispanic whites. In each ethnic group, after adjustment for age and gender, osteocalcin levels were inversely correlated with body mass index, fasting glucose and insulin, homeostasis model assessment of insulin resistance, triglycerides, and leptin, and positively correlated with adiponectin (P<0.001 for each variable). In multivariable regression analyses that adjusted for age, gender, smoking, serum creatinine, and statin and estrogen use, osteocalcin levels in the highest quartile (compared with the lowest quartile) were associated with a lower odds ratio (OR) of having MetSyn: OR (95% CI) in blacks, 0.33 (0.23 to 0.46); OR in non-Hispanic whites, 0.43 (0.31 to 0.63).
Conclusions: Serum osteocalcin is associated with measures of insulin resistance, adipokine levels, and the presence of MetSyn, suggesting a novel cross-talk between bone and adipose tissue.