Abstract / Summary
This study aimed to investigate the relationship between lipid parameters, the neutrophil-to-lymphocyte ratio (NLR), and insulin resistance in non-diabetic individuals. We conducted a retrospective cross-sectional analysis of the medical records of individuals aged ≥ 18 years who attended the Göztepe District Family Medicine Outpatient Clinic of Bozyaka Training and Research Hospital between 1 August 2021 and 1 August 2023. During data verification, homeostatic model assessment of insulin resistance (HOMA-IR) values were recalculated for all participants directly from fasting glucose and insulin measurements using the standard formula (fasting glucose [mg/dL] × fasting insulin [µIU/mL] / 405). Subjects were stratified into a case group (HOMA-IR > 2.5; n = 428) or a control group (HOMA-IR ≤ 2.5; n = 1,104). Demographic, clinical, and biochemical data were collected. Statistical analyses comprised parametric and non-parametric tests, correlation analyses, receiver operating characteristic (ROC) curve analyses, and multivariable logistic regression adjusted for age and sex. A total of 1,532 individuals were included. Compared with the control group, the case group was significantly older and had higher neutrophil counts, fasting glucose, HbA1c, triglyceride (TG), insulin, HOMA-IR, and TG to high-density lipoprotein cholesterol (TG/HDL-C) values and lower HDL-C levels, whereas total cholesterol, low-density lipoprotein cholesterol (LDL-C), and the NLR did not differ significantly. Women had significantly higher HDL-C levels than men in both groups ( p < 0.001). TG and the TG/HDL-C ratio were strongly correlated in both groups ( r ≈ 0.9, p < 0.001). ROC analysis showed that TG (cut-off ≥ 106 mg/dL; AUC = 0.641, 95% CI 0.610–0.672) and the TG/HDL-C ratio (cut-off ≥ 1.96; AUC = 0.644, 95% CI 0.612–0.675) had modest discriminative ability for insulin resistance, whereas the NLR showed no predictive value (AUC = 0.517). In multivariable logistic regression adjusted for age and sex, the TG/HDL-C ratio remained independently associated with insulin resistance (OR = 1.20 per unit; 95% CI 1.13–1.27; p < 0.001), whereas the NLR did not (OR = 0.99; p = 0.712). TG levels and the TG/HDL-C ratio may serve as simple, practical, and accessible adjunctive screening indices for insulin resistance in non-diabetic individuals, although their modest discriminative ability precludes their use as standalone diagnostic tools. The NLR alone is not a sufficient predictor. Not applicable.