January 08, 2019
2 min read

Fragility fractures may be unrelated to BMD in long-standing type 1 diabetes

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Bone mineral density for women with type 1 diabetes was lower at the femoral neck but higher at the lumbar spine compared with BMD for women without diabetes, and those with diabetes experienced more fragility fractures, findings published in the Journal of Diabetes and its Complications show.

This suggests that lower BMD may not be connected to fragility fractures in long-standing type 1 diabetes, according to researchers.

“While associations between diabetes complications and reduced BMD have been identified, the risk factors associated [with] lower BMD and subsequent fracture risk in [type 1 diabetes] is not completely understood,” Bruce A. Perkins, MD, professor of medicine in the division of endocrinology and metabolism and the Institute of Health Policy, Management and Evaluation at the University of Toronto, and colleagues wrote. “Furthermore, there are conflicting reports on the impact of poor glycemic control on BMD. As such, the mechanisms behind increased risk of fragility fracture in [type 1 diabetes] has not yet been determined, although several factors have been suggested, including poor glycemic control, and presence of diabetes-related complications, including retinopathy and neuropathy.”

Perkins and colleagues analyzed data from the Canadian Study of Longevity in Type 1 Diabetes on 75 adults with type 1 diabetes for at least 50 years (mean age, 66 years; 55% women) and 75 age- and sex-matched adults without diabetes (mean age, 65 years; 57% women) collected between February 2015 and September 2016. All participants made two visits to the University Health Network and Mount Sinai Hospital in Toronto. Visits were separated by 2 to 4 weeks and included phenotyping procedures. During the visits, BMD was measured by DXA at the lumbar spine, total hip and femoral neck, with BMD values represented by T-scores, and participants responded to questionnaires about bone health and fracture history.

Women with type 1 diabetes had a lower mean T-score at the femoral neck (–1.5) compared with women without diabetes (–1.2; P = .042). The opposite was true for T-scores at the lumbar spine (mean T-score with diabetes, –0.3; without diabetes, –1.1; P = .014). Fragility fractures were more prevalent in women with diabetes (17%) vs. those without the disease (2%; P = .021).

No significant difference in T-score was found at the total hip for women or at any of the three sites for men. Men with and without diabetes had similar rates of fragility fracture.

Among the cohort with type 1 diabetes, a history of fracture was more likely in women (adjusted OR = 2.9) and participants with macrovascular disease (aOR = 7.3). In addition, for every 1% increase in HbA1c, the researchers found a 4.13 jump in the adjusted OR for fragility fracture.

“The lack of association between BMD and fragility fracture in our study suggests that [type 1 diabetes] participants may have abnormal bone quality as a result of altered bone architecture as has been previously suggested,” the researchers wrote. “Further investigation of bone architecture in the long-duration cohorts are ongoing and will be important to provide a more comprehensive understanding of the changes in bone health that increases fragility fracture risk.” – by Phil Neuffer

Disclosures: Perkins reports he has received speaker honoraria from Medtronic, Johnson & Johnson, Roche, GlaxoSmithKline Canada, Novo Nordisk and Sanofi, as well as research grant support from Medtronic and Boehringer Ingelheim. He is also a consultant for Neurometrix. Please see the study for all other authors’ relevant financial disclosures.