Overweight and underweight are risk factors for vertebral fractures in patients with type 2 diabetes mellitus.

The aim of this cross-sectional study was to examine the association between body mass index (BMI) and the prevalence of vertebral fracture (VF) in Japanese patients with type 2 diabetes (T2DM). A total of 798 patients with T2DM were enrolled. VF was determined semi-quantitatively using lateral X-ray films. The association between BMI quartiles (Q1: ≤ 21.2 kg/m2, Q2: 21.3-23.4 kg/m2, Q3: 23.5-25.8 kg/m2, Q4: 25.9≤ kg/m2) and the presence of VF was examined. Multiple logistic regression analyses adjusted for age, sex, diabetes duration, hemoglobin A1c (HbA1c), estimated glomerular filtration rate, and albumin showed that Q1, Q3, and Q4 were significantly associated with an increased VF risk compared to Q2, which served as a reference [Q1; odds ratio (OR) = 1.91, 95% confidence interval (CI) 1.24-2.95, p = 0.004, Q3; OR = 1.65, 95% CI 1.07-2.55, p = 0.023, and Q4; OR = 2.18, 95% CI 1.39-3.41, p < 0.001]. Moreover, these associations remained significant after additional adjustment for femoral neck T-score, a bone resorption marker, urinary N-terminal cross-linked telopeptide of type-I collagen, and use of insulin and thiazolidinedione. Our study shows for the first time that both overweight and underweight were associated with the bone mineral density (BMD)-independent risk of VF in patients with T2DM. Therefore, body weight control should be considered as a protective measure against diabetes-related bone fragility.