Serum insulin-like growth factor-I is a marker for assessing the severity of vertebral fractures in postmenopausal women with type 2 diabetes mellitus

Summary Although previous studies indicated that serum insulin-like growth factor-I (IGF-I) was inversely associated with the presence of vertebral fractures (VFs), little is known whether serum IGF-I is associated with multiple VFs. We report that serum IGF-I could be clinically useful for assessing the severity of VFs in type 2 diabetic postmenopausal women. Introduction The number of VFs is associated with the mobility and mortality of the elderly people. Although serum IGF-I is inversely associated with the presence of VFs, little is known about the relationship between serum IGF-I and multiple VFs. Methods In this cross-sectional study, we recruited 479 men and 334 postmenopausal women with type 2 diabetes mellitus and measured serum IGF-I, bone mineral density, and bone turnover markers. Lateral X-ray films of the thoracic and lumbar spine were taken to diagnose the VF. Results In postmenopausal women, serum IGF-I level was decreased when the number of VFs was increased [no VFs; 138±51 ng/ml (mean ± SD) vs. one VF; 119±42 (p= 0.006), two VFs; 103±39 (p=0.002), and three and more VFs; 91±40 (p<0.001)]. Multiple logistic regression analysis adjusted for age, duration of diabetes, body mass index, serum creatinine, and HbA1c showed that serum IGF-I level was inversely associated with the presence of one VF [odds ratio (OR)=0.67, p=0.029], two VFs (OR= 0.40, p=0.017), as well as three and more VFs (OR=0.27, p=0.005). These associations were still significant after the additional adjustment for BMD at the lumbar spine. In contrast, no significant association of serum IGF-I level with VFs was found in men. Conclusions Serum IGF-I level was inversely associated with the number of prevalent VFs in postmenopausal women with type 2 diabetes, suggesting that serum IGF-I could be clinically useful for assessing the severity of VFs in the population.