Impact of body mass index on the association between kidney function and insulin resistance in diabetic and nondiabetic populations

Aims/Introduction

The kidneys play a role in regulating insulin metabolism, and kidney function may indicate the progression to insulin resistance (IR) in individuals with obesity and diabetes. We evaluated the relationship between kidney function biomarkers and IR in diabetic and nondiabetic adults categorized by body mass index (BMI).

Methods

A total of 8,272 adults from the China Health and Nutrition Survey 2009 were categorized into four groups based on BMI (overweight/obesity vs underweight/normal weight) and diabetes status (diabetes vs non-diabetes). Univariable and multivariable linear regression, along with restricted cubic spline regression, were used to determine the relationship between estimated glomerular filtration rate (eGFR), creatinine, urea nitrogen, uric acid (UA), and homeostasis model assessment for insulin resistance (HOMA-IR).

Results

The relationship between kidney function biomarkers and IR only existed in the overweight/obese populations and varied by diabetic status. In diabetic patients, linear associations were observed: eGFR was negatively associated with HOMA-IR, and creatinine was positively associated. In nondiabetic individuals, nonlinear associations were found. The relationship between eGFR and HOMA-IR followed an L-shaped curve: HOMA-IR decreased as eGFR increased up to 100 mL/min/1.73 m², then slightly increased. The UA-HOMA-IR association showed an inverted L-shape: HOMA-IR increased with higher UA levels, plateauing after UA exceeded 360 μmol/L.

Conclusions

Kidney function biomarkers are associated with IR in overweight/obese populations, with and without diabetes. eGFR and creatinine can be indicators of IR in overweight/obese subjects with diabetes, while eGFR and UA may be used in those without diabetes.