Plasma DPP4 activities are associated with osteoporosis in postmenopausal women with normal glucose tolerance

Abstract

Context: Inflammation, insulin resistance, dyslipidemia, and glucagon-like peptide-1 (GLP-1) are risk factors for osteoporosis. Dipeptidyl peptidase-4 (DPP4) is a newly identified adipokine related to these risk factors. Objective: To investigate the association between plasma DPP4 activities and osteoporosis. Design, Setting, and Patients: This was a cross-sectional study conducted in Guilin, China. A total of 744 postmenopausal women with normal glucose tolerance were studied. Main Outcome Measures: Plasma DPP4 activity, inflammatory markers, blood lipids, homeostatic model assessment of insulin resistance (HOMA-IR), active GLP-1, bone turnover markers, and bone mineral density (BMD) were measured in all participants. Results: Participants in the highest quartile of DPP4 activity had higher triglyceride, total cholesterol, HOMA-IR, IL-6, high-sensitivity C-reactive protein (hs-CRP), C-terminal telopeptide of type I collagen, and osteocalcin and lower BMD (lumbar spine and femoral neck) and active GLP-1 compared with participants in the lowest quartile (P = .05). DPP4 activities were associated positively with triglyceride, total cholesterol, HOMA-IR, IL-6, hs-CRP, C-terminal telopeptide of type I collagen, and osteocalcin and negatively with active GLP-1 and BMD (P = .05). In the highest DPP4 quartile, osteoporosis risk was significantly higher (odds ratio, 3.01; 95% confidence interval, 1.66-5.43) than in the lowest quartile after adjustment for potential confounders. The risk for osteoporosis increased more with higher levels of DPP4 activity, HOMA-IR, IL-6, and hs-CRP (P = .05), but not with higher levels of triglyceride and total cholesterol or lower levels of active GLP-1. Conclusions: This study shows that increased DPP4 activities are independently associated with osteoporosis. The mechanisms may be partly explained by the effect of DPP4 on inflammation and insulin resistance.