Correlation between systemic inflammation markers and insulin resistance in type 2 diabetes mellitus patients and its diagnostic value analysis

Background: Insulin resistance (IR) is a central pathophysiological feature of type 2 diabetes mellitus (T2DM) and is closely associated with chronic low-grade inflammation. Simple systemic inflammatory markers derived from routine laboratory testing may reflect this inflammatory-metabolic state; however, their clinical relevance in relation to IR remains incompletely defined. Methods: In this retrospective cross-sectional study, 2,177 patients with T2DM and 327 age- and sex-matched healthy controls were included. Insulin resistance was assessed using the homeostasis model assessment index (HOMA-IR), and patients with T2DM were classified as insulin-resistant or non-insulin-resistant based on established criteria. Systemic inflammatory markers, including the neutrophil-to-lymphocyte ratio (NLR), high-sensitivity C-reactive protein (hs-CRP), and white blood cell count (WBC), were analysed. Associations with IR were examined using correlation analysis and multivariable logistic regression. Receiver operating characteristic (ROC) curve analysis was performed to evaluate discriminative performance. Results: < 0.001). In multivariable logistic regression analysis, NLR remained independently associated with insulin resistance after adjustment for body mass index, glycated haemoglobin, and triglyceride levels. ROC analysis demonstrated that NLR had the highest area under the curve (AUC = 0.670), indicating modest discriminative ability, with higher sensitivity but lower specificity compared with hs-CRP and WBC. Conclusion: Systemic inflammatory markers, particularly NLR, are significantly associated with insulin resistance in patients with T2DM. Although the discriminative performance of NLR was modest, its simplicity, low cost, and availability from routine complete blood counts support its potential role as a complementary marker associated with IR rather than a standalone diagnostic tool. Prospective studies are needed to clarify temporal relationships and validate these findings across diverse populations.