['We found that serum osteocalcin (OC) and undercarboxylated OC (ucOC) levels were negatively associated with abdominal aortic calcification in type 2 diabetes mellitus (T2DM) men. This finding suggests that circulating OC and ucOC are not only related to glucose or fat metabolism but also to arteriosclerosis.', 'Recent studies revealed that serum osteocalcin levels were associated with not only bone metabolism but also glucose and fat metabolism. However, the relationship between serum OC levels and arteriosclerosis remains controversial. We examined whether or not bone metabolic markers including OC are associated with abdominal aortic calcification in patients with type 2 diabetes mellitus.', 'We recruited 118 men and 100 postmenopausal women with T2DM. We evaluated the abdominal aortic calcification score (ACS) on a lateral lumbar radiograph and examined the association between serum OC or undercarboxylated OC levels and ACS.', 'The ACS of 3 and greater, which corresponded well to the highest quartile, was significantly and negatively associated with serum OC and ucOC levels in men by logistic regression analyses after adjusting for age, BMI, serum levels of creatinine and LDL cholesterol, radial bone mineral density, smoking, duration of DM, hemoglobin A1c, and the index of insulin resistance [odds ratio (OR) 0.36, 95 % confidence interval (CI) 0.19-0.70, P\u2009<\u20090.005, and OR 0.28, 95 % CI 0.12-0.69, P\u2009<\u20090.01, per standard deviation increase in OC and ucOC, respectively]. These observations were still significant after an additional adjustment for other bone markers. In contrast, there were no significant relationships with serum OC or ucOC levels and ACS in women.'] Are serum osteocalcin levels inversely associated with abdominal aortic calcification in men with type 2 diabetes mellitus?