Correlation analysis of bone metabolism indices and glycosylated hemoglobin in middle-aged and older adult patients with type 2 diabetes mellitus

This study aimed to evaluate the association between bone metabolism indices and glycated hemoglobin (HbA1c) levels in middle-aged and older adult patients with type 2 diabetes mellitus (T2DM). We retrospectively analyzed 372 T2DM patients aged > 45 years who had attended the Endocrinology Department at our hospital (males, n = 192; postmenopausal females, n = 180). We collected data concerning patient characteristics, HbA1c levels, and bone metabolism indices (25-hydroxyvitamin D [25(OH)D], β-isomerized C-terminal telopeptides, N-terminal osteocalcin [N-MID], procollagen type 1 N-terminal propeptide [P1NP], bone-specific alkaline phosphatase [BAP], calcium [Ca], and phosphorus [P]). Study patients were divided into 3 groups according to their HbA1c levels: Group A, HbA1c < 7.5%; Group B, HbA1c 7.5 to 8.9%; and Group C, HbA1c ≥ 9.0%. Pearson correlation was used to determine the correlation between HbA1c levels and the bone metabolism indices. Multiple linear regression analysis was performed to identify factors influencing HbA1c in T2DM patients. Among the 3 groups, no differences were observed in 25(OH)D, β-CTx, Ca, or P indices among the 3 groups, whereas a statistically significant difference in N-MID was observed. Pearson correlation analysis showed an inverse correlation between HbA1c levels and N-MID and no correlation with other bone metabolism indices. Multiple linear regression analysis showed that N-MID was a factor influencing HbA1c levels after adjusting for age and body mass index (BMI). Serum N-MID levels negatively correlated with HbA1c levels in middle-aged and older adult men with T2DM. Therefore, high serum N-MID levels may contribute to blood glucose control in T2DM patients.