Serum fructosamine level and the risk of hip fracture in elderly women: A case-cohort study within the study of osteoporotic fractures

PURPOSE: While a high serum fructosamine level may be an indicator of undiagnosed diabetes, a low level may be indicative of poor nutrition or frailty. As malnutrition is a risk factor for osteoporosis, low serum fructosamine levels may be associated with an increased risk of osteoporotic fracture. We examined the association between serum fructosamine levels and the risk of subsequent hip and vertebral fracture. SUBJECTS AND METHODS: We performed a case-cohort study within the Study of Osteoporotic Fractures. Subjects were elderly, ambulatory, community-dwelling, Caucasian, women. Fructosamine levels were measured in baseline serum. Incident vertebral fractures were identified by comparing baseline spinal radiographs to those obtained an average of 3.5 years later. Hip fractures were confirmed by radiograph. We randomly selected 101 women who suffered a hip fracture, 100 women who developed a vertebral fracture, and 276 controls. We compared fructosamine levels in women with subsequent osteoporotic fractures to controls. All analyses were adjusted for age, weight, and use of estrogens. RESULTS: Women with fructosamine levels in the lowest decile (≤223 μmol/L) had a three-fold increase in the risk of hip fracture (95% confidence interval 1.4-6.4), compared with all other women. Adjustment for markers of frailty, including smoking, functional status, and serum albumin levels, reduced the strength of this association. No clear association was observed between serum fructosamine level and the risk of vertebral fracture. CONCLUSION: Low serum fructosamine levels, which likely reflect frailty or malnutrition, may be a useful clinical tool to identify women at risk for hip fracture.