Objective To analyze the relationship between serum N-MID osteocalcin (N-MID), β-cross-linked C-telopeptide of type Ⅰ collagen (β-CTX) levels and bone metabolism in patients with type 2 diabetes mellitus.

Methods A total of 235 patients with type 2 diabetes mellitus diagnozed and treated from February 2017 to February 2020 were included.The patients were divided into normal bone mass group (n=94), osteopenia group (n=92) and osteoporosis group (n=49) according to bone mineral density (BMD). Serum levels of N-MID, β-CTX, parathyroid hormone (PTH), and 25(OH)D3 were measured and compared among the three groups. The correlation between serum N-MID, β-CTX and BMD, PTH, and 25(OH)D3 were analyzed. Receiver-operating characteristic curve was employed to assess the capability of biochemical parameters to distinguish osteoporosis.

Results The age and course of diabetes mellitus were increased in normal bone mass, osteopenia group, and osteoporosis groups in sequence (P < 0.01). The levels of serum N-MID, β-CTX, and PTH in osteoporosis group were significantly higher than those in normal bone mass group and osteopenia group (P < 0.05). Pearson analysis showed that serum N-MID and β-CTX levels were negatively correlated with BMD (P < 0.05) and positively correlated with PTH (P < 0.05). Howere there was no relationship between N-MID, β-CTX and 25(OH)D3. The serum N-MID was positively correlated with β-CTX (P < 0.01). The area under the curve for N-MID and β-CTX to distinguish osteoporosis from normal bone mass were 0.86 and 0.85, and the specificity were 100.00% and 96.81%, respectively(P < 0.001).

Conclusions The determination of serum levels of N-MID and β-CTX is helpful to understand the changes of bone metabolism of type 2 diabetes mellitus with osteoporosis, so that to provide evidence for the evaluation of condition.