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The Exchange T2DM and Osteoporosis: Where Do We Stand in 2019?

T2DM and Osteoporosis: Where Do We Stand in 2019?

T2DM and Osteoporosis: Where Do We Stand in 2019? Posted By:
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Bone mineral density (BMD) in type 2 diabetics is trending higher and higher, and BMI is associated with type 2 diabetes mellitus (T2DM). However, higher BMD T-scores are associated with stronger bone and decreased fracture risk. Yet, type 2 diabetics have a 1.5 times higher likelihood of increased fracture compared to non-diabetic populations. When this is combined with an increased risk for falls and an ever-increasing prevalence of diabetes, population health could be seriously impacted.

How do we explain this conundrum of unexpected BMI and BMD scores with increased fracture risk? Part of the answer lies in bone quality, which we do not measure with BMD. The formula for bone strength equals bone density plus bone quality. The components of bone quality include microarchitecture, mineralization, bone turnover, and accumulated microscopic damage.

Trabecular bone score (TBS) is an independent measure of bone quality that measures microarchitecture; because microarchitecture is altered in diabetics, it can identify patients at higher risk. The measurement is a software application that can be added to conventional BMD DXA machines (not widely available). In T2DM, TBS is lower compared to non-diabetic controls and is considered an independent risk factor for fracture. It measures bone texture correlated with bone microarchitecture and can identify increased risk, with lower scores indicating higher risk.

Measurements of bone markers of formation and degradation have been contradictory as bone turnover markers are of a lower state of turnover. Lower turnover is associated with bone stabilization, and this does not explain the increase in cortical porosity. Therefore, bone turnover markers are not employed to predict fracture in this population.

This brings us back to BMD with the knowledge that risk for fracture thresholds in T2DM are not yet well identified. We are left with T-scores of -2.5 standard deviation below the mean in any one site, or a central fracture to diagnose osteoporosis, as we do with non-diabetic populations. Since we know that BMD underestimates fracture risk in patients with diabetes, it has been suggested that the threshold be moved to a T-score of -2.0 at spine or hip, and when adjusted with age, that this could be used as a guide to therapeutic intervention. This notion is appealing but controversial.

In 2019 we are left without clear guidelines in both the osteoporosis and the diabetes literature. The first choice for these patients remains bisphosphonates, and although there are no studies on denosumab in T2DM, this may be a preferred option in our older diabetic population.

In conclusion, it goes without saying that new trials in this population would be advantageous, as developing clearer thresholds for intervention and specific treatment medication guidelines would be beneficial.

Reference
  • Ferrari SL, Abrahamsen B, Napoli N, et al. Diagnosis and management of bone fragility in diabetes: and emerging challenge. Osteoporos Int. 2018;29:2585-2596.
  • Johnston SS, Conner C, Aagren M, Ruiz K, Bouchard J. Association between hypoglycemic events and fall-related fractures in Medicare-covered patients with type 2 diabetes. Diabetes Obes Metab. 2012;14:634-643.
  • Schwartz AV, Vittinghoff E, Bauer DC, et al. Association of BMD and FRAX score with risk of fracture in older adults with type 2 diabetes. JAMA. 2011;305:2184-2192.

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