Triglyceride-glucose index and reduced kidney function in hypertensive Nigerian adults: independent association within the cardio-renal continuum

Abstract

BACKGROUND: Reduced kidney function is a major contributor to cardiovascular morbidity and mortality worldwide, particularly among individuals with hypertension. The triglyceride-glucose (TyG) index, a surrogate marker of insulin resistance, has been associated with renal dysfunction in multiple populations; however, data from Sub-Saharan Africa remain limited. We examined the association between the TyG index and reduced kidney function among hypertensive Nigerian adults. METHODS: In this cross-sectional study, 1,470 consecutively presenting hypertensive adults aged ≥ 18 years at a cardiac center in Lagos, Nigeria (2009-2024) were analyzed. Individuals with known diabetes, fasting glucose ≥ 126 mg/dL, pregnancy, acute kidney injury, or incomplete data were excluded. Reduced kidney function was defined as estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m² using the CKD-EPI 2021 race-free equation. The TyG index was analyzed as quartiles and as a standardized continuous variable. Multivariable logistic regression models were constructed. Sensitivity analyses included adjustment for HbA1c and exclusion of participants with HbA1c ≥ 6.5%. Restricted cubic spline and receiver operating characteristic analyses were performed. Estimated 10-year cardiovascular risk was calculated using the Framingham Risk Score. RESULTS: Reduced kidney function was present in 36.7% of participants. Compared with the lowest TyG index quartile, individuals in the highest quartile had higher odds of reduced kidney function (fully adjusted OR 3.14; 95% CI 2.25-4.39). Each 1-standard deviation increase in TyG index was associated with higher odds (adjusted OR 1.49; 95% CI 1.31-1.70). The association remained robust after adjustment for HbA1c and exclusion of participants with elevated HbA1c. Restricted cubic spline analysis demonstrated a log-linear relationship (p for non-linearity = 0.43). The TyG index showed modest discrimination (AUC 0.664). CONCLUSIONS: Higher TyG index values are independently associated with reduced kidney function in hypertensive Nigerian adults, supporting a graded relationship between metabolic dysfunction and renal impairment. The TyG index may serve as a simple adjunct tool for cardio-renal risk stratification in resource-limited settings.