Nonlinear association between serum insulin, visceral fat area, and kidney function in female with type 2 diabetes: a...

To investigate the nonlinear associations between fasting insulin (FIns), visceral fat area (VFA), and estimated glomerular filtration rate (eGFR) in female patients with type 2 diabetes mellitus (T2DM), and whether there is a threshold effect.

This retrospective analysis utilized electronic medical record data from patients with female patients with T2DM who presented to a tertiary hospital in Chengdu, Sichuan Province, between November 1, 2018, and April 30, 2023. Collected data encompassed general demographic characteristics as well as biochemical parameters. The nonlinear associations between FIns, VFA, and eGFR were evaluated using restricted cubic splines and threshold analyses.

A total of 620 female patients with T2DM were initially enrolled; following the exclusion of 25 individuals with incomplete data, 595 female patients were included in the final analysis. After adjusting for confounders such as age and body mass index, significant nonlinear effects were observed in the associations between FIns, VFA, and eGFR. Specifically, there is no threshold between FIns and eGFR; when FIns is <70.28 pmol/L, there is no significant association between FIns and eGFR (β = -0.01, 95% CI: -0.125, 0.105); above 70.28 pmol/L, FIns was negatively correlated with eGFR (β = -0.083, 95% CI: 0.143, 0.023). The threshold for VFA in relation to eGFR was identified as 73.6 cm². When VFA was less than 73.6 cm², a positive correlation with eGFR was observed (β = 0.139, 95% CI: 0.015, 0.262), whereas VFA exceeding this threshold was negatively correlated with eGFR (β = -0.197, 95% CI: -0.33, -0.064).

A nonlinear association was observed between FIns, VFA, and renal function; whereas a distinct clinical threshold was evident in the association between VFA levels and renal function. When FIns levels exceed 70.28 pmol/L, FIns shows a negative correlation with renal function, which may serve as a reference for establishing thresholds in future studies; a VFA of 73.6 cm² represent pivotal inflection points at which renal function transitions from compensatory processes to impairment. This investigation provides novel quantitative evidence for risk stratification of renal function in female patients with T2DM, obesity, and related metabolic disturbances.