A Retrospective Analysis of the Association between Serum Uric Acid Levels and Insulin Resistance Degrees in Individuals Undergoing Health Examination

Background Insulin resistance (IR) has been witnessing an upward trend in incidence rates, with a high comorbidity rate with obesity, dyslipidemia and hyperuricemia. However, the correlation between IR, obesity/dyslipidemia and SUA levels is not well understood. Objective To explore the dose-response correlation between homeostatic model assessment for IR (HOMA-IR) and SUA levels, and to evaluate the mediating effect of HOMA-IR on obesity/lipids and SUA levels. Methods We conducted a retrospective study that a total of 3 928 adults who underwent physical examination in the Seventh Affiliated Hospital, Southern Medical University from November 2021 to December 2022 were selected and divided into males and females, non-IR and IR subgroups. The dose-response correlation between HOMA-IR and SUA was analyzed by restricted cubic spline (RCS) . The mediating effects of HOMA-IR on correlation between obesity, total cholesterol (TC) , triacylglycerol (TG) , low-density lipoprotein cholesterol (LDL-C) , high-density lipoprotein cholesterol (HDL-C) and SUA levels were analyzed. Linear regression model was used to analyze the correlation between SUA levels and HOMA-IR, fasting blood insulin (FINS) , and fasting blood glucose (FBG) . Results Among the 3 928 patients, 3 026 were males and 902 were females. Among the 3 026 males, 757 were IR patients and 2 269 were non-IR patients. The levels of systolic blood pressure (SBP) , diastolic blood pressure (DBP) , SUA, HOMA-IR, FINS, FBG, BMI, waist-hip ratio (WHR) , TG, TC and LDL-C were higher in IR patients than in non-IR patients, age and HDL-C levels were lower in IR patients than in non-IR patients (P<0.05) . Among the 902 females, 226 were IR patients and 676 were non-IR patients. The levels of SBP, DBP, SUA, HOMA-IR, FINS, FBG, BMI, WHR, TG, LDL-C were higher in IR patients than in non-IR patients, HDL-C levels were lower in IR patients than in non-IR patients (P<0.05) . The RCS results showed that there was a non-linear dose-response correlation between HOMA-IR and SUA levels after adjusting covariates, with gender differences presented in this correlation. The SUA levels in males exhibited an approximate ∩-shaped trend (Pnonlinear=0.002) with the increase of HOMA-IR. While in females, SUA levels showed a trend of increasing and then constant (Pnonlinear=0.002) . Whereas, as SUA levels increased, HOMA-IR showed a trend of decreasing and constant in males (Pnonlinear=0.002) , while HOMA-IR showed a U-shaped trend in females (Pnonlinear=0.002) . The results of mediation analysis showed that HOMA-IR partially mediates the correlation between obesity, central obesity, TG and SUA, and the ratio of mediation effect to the total effect was 9.5%, 7.9% and 5.3% in males, 36.1%, 19.9% and 6.5% in females, respectively. HOMA-IR completely mediated the correlation between HDL-C and SUA, and the ratio of mediating effect to total effect was 20.0% in males and 22.0% in females. The patients were stratified by SUA=7.28 mg/dL in males and 4.70 mg/dL in females, respectively. After adjusting covariates, in males, the results of linear regression model analysis showed a negative correlation between SUA and FBG levels (P<0.05) , and individuals SUA≥7.28 mg/dL showed a positive correlation between SUA and FINS levels (P<0.05) ; in females, individuals SUA≥4.70 mg/dL showed a positive correlation between HOMA-IR, FINS and SUA (P<0.05) . Conclusion There is a nonlinear dose-response correlation between HOMA-IR and SUA levels. HOMA-IR has a partial mediating effect on the correlation between obesity, TG and SUA levels, and a complete mediating effect on the correlation between HDL-C and SUA levels. FBG is negatively correlated to SUA levels in males.