Hyperglycemia is associated with increased bone mineral density and decreased trabecular bone score in elderly Japanese men: The Fujiwara-kyo osteoporosis risk in men (FORMEN) study

Purpose Patients with type 2 diabetes mellitus (T2DM) have an increased fracture risk despite having higher areal bone mineral density (aBMD). This study aimed to clarify the association between glycemic and insulin resistance status and bone microarchitecture, and whether pentosidine and bone turnover markers play any roles in the association. Methods A total of 2012 community-dwelling men aged ≥ 65 years completed baseline measurements of spine aBMD, fasting plasma glucose (FPG) and serum insulin, hemoglobin A1c (HbA1c), osteocalcin, type I procollagen N-terminal propeptide, type I collagen C-terminal crosslinking telopeptide, tartrate-resistant acid phosphatase isoenzyme 5b, pentosidine, height and weight and an interview regarding past disease history. Homeostasis model assessment-insulin resistance (HOMA-IR) was also calculated. T2DM was defined as physician-diagnosed middle age or elderly-onset diabetes mellitus, or according to biochemical test results. To evaluate bone microarchitecture, trabecular bone score (TBS) was calculated at the same vertebrae as those used for aBMD measurement. Results After excluding participants who had a disease history and/or were taking medications affecting bone metabolism, 1683 men (age, 72.9 ± 5.2 years) were analyzed. Men with T2DM had significantly higher aBMD compared to those without T2DM. There was no significant difference in TBS. However, FPG, HbA1c and HOMA-IR levels were significantly inversely correlated with TBS after adjusting for age, BMI and aBMD. Multivariate linear regression analyses revealed that glycemic indices (FPG and HbA1c) were significantly associated with increased aBMD and decreased TBS, and that HOMA-IR was associated only with TBS. These associations did not change after further adjusting for bone turnover makers and pentosidine levels. Conclusions Hyperglycemia and elevated insulin-resistance were associated with low TBS independently of bone turnover and pentosidine levels.