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Large weight loss raises fragility fracture risk in type 2 diabetes

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March 15, 2018

Adults with type 2 diabetes who lost at least 30% of their maximum body weight had increased risks for fragility fractures and any fracture compared with those who lost less weight, according to findings published in Diabetes Care.

Masanori Iwase, MD, PhD, of the department of medicine and clinical science in the Graduate School of Medical Sciences at Kyushu University in Japan, and colleagues evaluated data from the Fukuoka Diabetes Registry on 2,755 men and 1,951 postmenopausal women with type 2 diabetes (mean age, 66 years) to determine the relationship between weight loss and risk for fracture. Follow-up was a median of 5.3 years. Participants were divided into groups based on weight loss from maximum weight: less than 10% (reference group; n = 2,014; 42.5% women), 10% to less than 20% (n = 1,852; 41.1% women), 20% to less than 30% (n = 699; 40.3% women) and at least 30% (n = 141; 37.6% women).

At the end of follow-up, 198 of participants sustained a fragility fracture (55 hip fractures; 144 spine fractures). The incidence rates of fragility fractures were higher in all participants, particularly men, with at least 30% body weight loss (P for trend < .001 for both) compared with the other body weight-loss groups. In postmenopausal women, a similar trend was observed, but it was not statistically significant.

Compared with the reference groups (those who lost < 10% of body weight), the age- and sex-adjusted HRs for fragility fractures for the groups who lost at least 30% body weight were 3.22 (95% CI, 1.85-5.6) in all participants, 6.63 (95% CI, 2.88-15.27) in men and 2.17 (95% CI, 1.02-4.65) in postmenopausal women.

Fractures at any site were sustained by 662 participants (249 in men; 413 in postmenopausal women). The incidence rates for any fracture were higher in the groups that lost at least 30% body weight for all participants (P for trend = .004) and men (P for trend < .001) compared with the other body weight-loss groups. Compared with the reference groups, the age- and sex-adjusted HRs for any fracture for the groups that lost at least 30% body weight were 2.16 (95% CI, 1.53-3.07) in all participants, 2.61 (95% CI, 1.56-4.37) in men and 1.82 (95% CI, 1.13-2.93) in postmenopausal women.

“Our study demonstrates that greater [body weight] loss from maximum [body weight] increases future fracture risk in patients with type 2 diabetes, especially in men,” the researchers wrote. “Although patients with diabetes often lose weight whether intentionally or unintentionally, preventive measures for fragility fractures should be considered in those who lose > 20% of the maximum [body weight].” – by Amber Cox

Disclosures: The authors report no relevant financial disclosures.

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Perspective

It has long been thought that obesity may be a protective factor for development of osteoporosis and fragility fractures. However, epidemiologic studies have shown an increase in fracture risk in patients with type 2 diabetes, despite the obesity that often occurs with the disease. In patients with type 2 diabetes, axial bone mineral density is generally normal or higher, but complications (such as neuropathy and visual impairment) increase the risk for falling and thus contribute to the increased fracture risk. Further, it has been hypothesized that neuropathy and chronic kidney disease may adversely impact regional bone mass and quality. Other factors, including treatment-induced bone loss, may accentuate an underlying skeletal fragility, increasing the risk for fracture in these patients.

Despite the increased risk of fracture in patients with type 2 diabetes, current fracture prevention strategies do not differ between patients with diabetes and the general public — the current clinical recommendations suggest that clinicians assess fracture history and risk factors in patients with diabetes and recommend measurement of BMD if appropriate for the patient’s age and sex.

Recent clinical evidence supports an increased risk for fracture in patients without diabetes who have achieved significant weight loss. Further, weight loss after age 50 years in women has been shown to increase the risk for hip fracture. This study by Iwase and colleagues is an important one in that it gives the clinician an additional risk factor (significant weight loss) to help identify a subset of patients with type 2 diabetes who may be at increased risk for fracture. This new criterion may lead to increased screening, treatment of osteoporosis and prevention of fracture. My hope is that continued research in this area will help determine the underlying mechanism behind the increased risk of fracture after weight loss.

Matthew P. Gilbert, DO, MPH

Associate Professor of Medicine
Division of Endocrinology and Diabetes
Program Director, Fellowship in Endocrinology and Diabetes
The Robert Larner, MD, College of Medicine at The University of Vermont

 

Disclosure: Gilbert reports he has been a consultant for Novo Nordisk and Sanofi.