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Given that patients with type 2 diabetes often have normal or even high BMD, should they be treated for bone fragility?
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Currently no evidence-based recommendations are available for the diagnosis or treatment of osteoporosis in patients with diabetes.
Patients with type 2 diabetes pose a diagnostic and prognostic dilemma due to the limitations of BMD measurement in predicting fractures in these patients. The mechanism behind the increased risk for bone fragility and fracture in these patients is likely multifactorial, and the current available osteoporosis treatment regimens do not adequately address these multiple underlying mechanisms.
Therefore, good glycemic control and reducing the risks for falls are the most essential components for decreasing the risks for bone fragility and fracture in patients with diabetes. Diabetic vascular complications may directly contribute to bone fragility as well as increase an individual’s risk for falls, and it is well established that adequate glycemic control prevents or reduces the risks for micro- and macrovascular complications. Further, glycemic control may reduce the non-enzymatic glycosylation of collagen, a potential cause of bone fragility.
In addition to glycemic control, several clinical studies have demonstrated the importance of implementing established methods to reduce the risk for falls. These methods include regular exercise, improvement in muscle strength, balance training, withdrawal of psychotropic medications, and regular visual assessment.
Clinicians should also make sure their patients with diabetes are meeting the current recommendations for calcium intake and vitamin D levels, particularly as medications used in the treatment of diabetes may have an impact on bone metabolism. A better understanding of the biological mechanisms and impact on bone metabolism of the various classes of diabetes medications is essential to aid clinicians in their decision making regarding the different medications available for the treatment of diabetes.
Matthew P. Gilbert, DO, MPH, is associate professor of medicine in the division of endocrinology and diabetes at University of Vermont College of Medicine. He reports no relevant financial disclosures.
If patients are having fragility fractures, then some form of usual anti-osteoporosis therapy may be required, as long as there is no contraindication.
Therapeutic recommendations are usually guided by clinical trial data. Unfortunately, among patients with diabetes — both type 1 and 2 — there is a paucity of clinical trial evidence to inform treatment decisions. It is true that patients with type 2 diabetes often have normal or elevated BMD for a variety of reasons. However, these patients may have an increase of fragility fractures. Bone strength equals bone quantity plus bone quality, so the presumption is that bone quality is impaired in diabetes, and this is probably correct.
To complicate matters, in patients with type 2 diabetes, the predominant problem is decreased bone formation rather than increased resorption, although of course both could occur.
There are simply not enough data to make definitive treatment recommendations. However more sophisticated investigations are available, for example, trabecular bone score, high-resolution quantitative computed tomography or even bone biopsy, that may help to make empirical treatment decisions. As more information becomes available, particularly measurements of bone quality linked to fracture risk, then clinicians may be better able to recommend appropriate treatment.
Robert G. Josse, BSc, MBBS, FRCP, FRCPC, FACP, FACE, is associate scientist at Li Ka Shing Knowledge Institute and professor of medicine at the University of Toronto. He reports receiving grants or personal fees from Amgen, AstraZeneca, Boehringer Ingelheim, Eli Lilly, Janssen and Merck.