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Hyperglycemia, insulin resistance tied to low trabecular bone score in older men

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August 18, 2017

Japanese men with hyperglycemia and higher levels of insulin resistance are more likely to have a lower trabecular bone score than men who are not insulin resistant, suggesting deteriorated bone microarchitecture and increased fracture risk, according to findings published in Bone.

“Although they represent different disease entities, diabetes mellitus, either type 1 or type 2, has been reported to increase the risk of fracture,” Masayuki Iki, MD, PhD, professor in the department of public health at Kindai University in Osaka, Japan, and colleagues wrote. “Interestingly, patients with type 2 diabetes mellitus often show significantly higher areal bone mineral density compared to nondiabetic controls. Therefore, nonbone mass features representing bone strength, or bone quality, may play a substantial role in increasing fracture risk in patients with [type 2 diabetes].”

Iki and colleagues analyzed data from 1,683 men aged at least 65 years from four cities of Nara prefecture in Japan participating in the ongoing FORMEN study. Participants completed a 250-item medical history questionnaire and provided fasting blood samples. Researchers measured fasting plasma glucose, HbA1c, serum insulin, creatinine, triglycerides and cholesterol, as well as the bone turnover markers osteocalcin, type 1 procollagen N-terminal propeptide, tartrate-resistant acid phosphatase isoenzyme 5b, serum type 1 collagen cross-linking C-terminal telopeptide and serum pentosidine levels. Participants underwent DXA measurements at the lumbar spine to assess areal BMD; trabecular bone score was calculated from the same DXA scans.

Within the cohort, 198 men had type 2 diabetes (median duration, 10.5 years); 184 received pharmaceutical treatment. Men with type 2 diabetes had a higher areal BMD compared with men who did not have type 2 diabetes.

Researchers did not observe any between-group differences in trabecular bone score; however, FPG, HbA1c and homeostatic model assessment of insulin resistance levels were inversely correlated with trabecular bone score after adjustment for age, BMI and areal BMD. In multivariate linear regression analyses, researchers found that FPG and HbA1c were both associated with increased areal BMD and decreased trabecular bone score. FPG had a positive regression coefficient of 0.012 (95% CI, 0.005-0.02) for areal BMD and a negative regression coefficient of –0.004 for trabecular bone score (95% CI, –0.007 to –0.0003). HbA1c, similarly, had a positive regression coefficient of 0.012 (95% CI, 0.004-0.019) for areal BMD and a negative regression coefficient of –0.004 for trabecular bone score (95% CI, –0.007 to –0.000) Insulin resistance was only associated with trabecular bone score (–0.006; 95% CI, –0.011 to –0.002). The associations persisted after adjusting for bone turnover makers and pentosidine levels, according to researchers.

“These results were independent of serum pentosidine levels or bone turnover markers, suggesting that the deterioration of trabecular bone microarchitecture was possibly caused by prolonged hyperglycemic status due to insulin resistance, and that this association may not be mediated by low bone turnover or retention of pentosidine,” the researchers wrote.

The researchers noted that the cohort is part of an ongoing study that plans a 10-year follow-up with three waves of clinical surveys at a university hospital, where incident fractures can be identified and the role of trabecular bone score can be further evaluated. – by Regina Schaffer

Disclosure: One of the authors reports working as a senior scientist at Med-Imaps at the time of the study.

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