Triglyceride-high-density cholesterol-glucose-body index and risk of impaired fasting glucose in normolipidemic adults: a secondary analysis of a multicenter cohort

Abstract

The triglyceride-high-density cholesterol-glucose-body index (TyHGB) is a composite index incorporating routinely measured lipid, glucose, and anthropometric parameters. However, its longitudinal association with the risk of impaired fasting glucose (IFG), a critical prediabetic stage, remains unreported in apparently healthy adults with normal baseline fasting plasma glucose (FPG) and lipid profiles. This study aimed to investigate the association between the TyHGB index and the risk of incident IFG among Chinese adults with normal baseline FPG and lipid levels. To evaluate the longitudinal progression to IFG, this secondary retrospective cohort study included 57,097 Chinese adults who were initially free of IFG, possessing normal baseline FPG (< 5.6 mmol/L) and lipid profiles. The baseline TyHGB index was calculated using triglycerides, high-density lipoprotein cholesterol, FPG, and body mass index. The primary outcome was the incidence of IFG. Cox proportional hazards regression and logistic regression models were utilized to quantify the association between the TyHGB index and incident IFG risk. Restricted cubic splines (RCS) and piecewise models were employed to explore potential nonlinear relationships and threshold effects. Additionally, subgroup and sensitivity analyses were conducted to evaluate the stability and robustness of the primary associations. During a median follow-up of 2.97 years, 5,491 (9.62%) initially normoglycemic participants developed incident IFG. A higher TyHGB index was significantly associated with an elevated risk of incident IFG. In the fully adjusted Cox proportional hazards model, each 1-unit increase in the TyHGB index was associated with a hazard ratio (HR) of 2.41 (95% CI: 2.30–2.52). Compared to Q1, participants in Q4 exhibited a significantly higher risk, with an HR of 5.85 (95% CI: 5.26–6.51). RCS analysis revealed a significant nonlinear, piecewise relationship ( P for nonlinearity < 0.001) with a threshold inflection point at a TyHGB index of 6.97. The positive association was generally observed across prespecified subgroups, although effect sizes varied across several clinical strata, and the results remained robust in sensitivity analyses. A higher TyHGB index was associated with incident IFG among Chinese adults with normal baseline FPG and lipid levels below dyslipidemia thresholds. Whether TyHGB provides additional clinical value beyond conventional risk factors requires prospective validation and formal predictive-performance assessment. Not applicable.