Summary:​ This study aims to investigate the role of obesity and diabetes on bone health in a nation-wide cohort of women with high risk of fracture.

Introduction:​ The role of obesity and diabetes on fracture risk is yet poorly understood. Body mass index (BMI) and bone mineral density (BMD) are strongly correlated;​ however, patients with elevated BMI are not protected against fractures, configuring the obesity paradox. A similar controversial association has been also found in diabetic patients. Herein, we present a retrospective analysis on 59,950 women.

Methods:​ Using a new web-based fracture risk-assessment tool, we have collected demographic (including BMI), densitometric, and clinical data (including history of vertebral or hip and non-vertebral, non-hip fractures, presence of comorbidities). We performed a propensity score generation with 1:​1 matching for patients in the obese (BMI ≥ 30) and non-obese (BMI < 30) groups, in the diabetics and non-diabetics. Propensity score estimates were estimated using a logistic regression model derived from the clinical variables:​ age, lumbar spine T-score, and femoral neck T-score.

Results:​ We found an association between diabetes and fractures of any kind (OR 1.3, 95% CI 1.1–1.4 and 1.3, 95% CI 1.2–1.5 for vertebral or hip fractures and non-vertebral, non-hip fractures, respectively). Obesity, on the other hand, was significantly associated only with non-vertebral, non-hip fractures (OR 1.3, 95% CI 1.1–1.6). To estimate the individual effect of obesity and diabetes on bone health, we ran sensitivity analyses which included obese non-diabetic patients and non-obese diabetic patients, respectively.

Conclusions:​ Non-obese diabetics had the highest risk of vertebral or hip fracture, whereas obese non-diabetics predominantly had non-vertebral, non-hip fracture’s risk. These results should raise awareness in clinical practice when evaluating diabetic and/or obese patients.