hs-CRP/HDL Ratio Across Obesity and Type 2 Diabetes Mellitus Phenotypes in Adults: A Cross-Sectional Study

Background/Objectives: Chronic low-grade inflammation and lipid metabolism play an important role in the development of obesity and type 2 diabetes mellitus (T2DM). The ratio of high-sensitivity C-reactive protein to high-density lipoprotein cholesterol (hs-CRP/HDL-C) integrates these pathways and it has been proposed as a novel biomarker of metabolic risk. However, evidence regarding its association with obesity and T2DM remains limited. Methods: This retrospective cross-sectional study included data from 413 adults, comprising 251 individuals with T2DM and 162 individuals without T2DM. Obesity status was assessed separately according to BMI categories. The hs-CRP/HDL-C ratio was divided into quartiles, with the lowest quartile used as the reference category. Its associations with obesity and T2DM were evaluated using multivariable logistic regression and restricted cubic spline analysis. Subgroup analyses were conducted to evaluate the consistency of these associations across different population subgroups. Results: A significantly positive association was noted between the hs-CRP/HDL-C ratio and the presence of T2DM. Compared with individuals in the lowest quartile, those in the higher quartiles of the hs-CRP/HDL-C ratio had significantly higher odds of T2DM. In the fully adjusted model, each unit increase in the hs-CRP/HDL-C ratio was associated with higher odds of T2DM (OR = 1.59, 95% CI: 1.14–2.20, p = 0.006), whereas the association with obesity was attenuated and lost statistical significance after full adjustment. RCS analysis confirmed a significant overall association between the hs-CRP/HDL-C ratio and T2DM risk (p-overall = 0.034). Although the hs-CRP/HDL-C ratio was associated with obesity in the crude model (OR = 1.40, 95% CI: 1.05–1.70, p = 0.019), the association was not significant after adjustment (OR = 1.18, 95% CI: 0.90–1.56, p = 0.229). Conclusions: In our study, an elevated hs-CRP/HDL-C ratio was significantly associated with the presence of T2DM and may represent a marker associated with metabolic inflammation, particularly in individuals with glycometabolic disorders.