Triglyceride glucose index is associated with vertebral fracture in older adults: a longitudinal study

Diabetes is a risk factor for bone fractures. However, the association between insulin resistance and the risk of fracture has not been well studied. In the present study, we explored the association of the triglyceride glucose index as a measure of insulin resistance with the risk of vertebral fracture in older adults.

A total of 1995 subjects aged 50 years or older who underwent computed tomography (CT) for lung cancer screening from 2016-2021 were included in this study. They were followed until July 2023. Demographic information and laboratory test data were collected from the electronic medical system. Vertebral fractures were evaluated on the basis of sagittal CT images of the spine. The triglyceride glucose (TYG) index was calculated via the following equation: Ln [fasting glucose (mg/dl)×fasting triglyceride (mg/dl)/2]. The association between the TYG index and vertebral fracture incidence was evaluated via a multivariable Cox proportional hazards model.

Ninety-five cases of fracture were observed during the 60 months of follow-up. The incidence of fracture was lower for the fourth TYG index than for the first TYG index (3.26% vs. 6.00%, P = 0.04). The risk of vertebral fracture decreased with increasing TYG index (adjusted hazard ratio (aHR): 0.56, 95% confidence interval (CI): 0.35-0.90). Fracture risk was significantly lower in subjects with the highest TYG (the fourth quartile) than in those with the first quartile (aHR: 0.46, 95% CI: 0.22-0.96) according to the fully adjusted model. A similar association was observed in subjects without diabetes (aHR = 0.44, 95% CI: 0.21-0.95). Restricted cubic splines further revealed that the risk of vertebral fracture decreased with increasing TYG index.

A greater TYG index was associated with a lower risk of vertebral fracture, independent of body mass index and bone mass.