Background <p>The use of statins and other lipid-lowering therapies for nephrotic syndrome (NS) patients with dyslipidemia remains controversial. This study aimed to evaluate the impact of long-term statin therapy on the risk of developing diabetes mellitus (DM) in patients with NS.</p> Methods <p>A retrospective cohort study was conducted from January 2018 to December 2024. The association between statin use and the incidence of diabetes was evaluated using Cox proportional hazards regression. Restricted cubic splines were utilized to investigate potential nonlinear relationships between cumulative statin dose and diabetes risk. Subgroup analyses were performed according to age, sex, corticosteroid use, and other relevant clinical factors to assess possible effect modification.</p> Results <p>A total of 837 eligible NS patients were enrolled in this study, among whom 84 (10.03%) developed DM. Statin use significantly increased the risk of incident diabetes (HR 3.68, 95% CI: 1.95–6.94, <i>p</i> &lt; 0.001), an association which remained significant after multivariable adjustment (HR 3.00, 95% CI: 1.40–6.43, <i>p</i> = 0.005). Higher risk was particularly evident among older patients (≥ 55 years), those with hypertension, corticosteroid non-users, and patients with BMI ≥ 28. A restricted cubic spline analysis indicated a nonlinear relationship between cumulative statin dose and diabetes risk, peaking at cumulative doses of approximately 8,000–13,000&#xa0;mg and declining thereafter.</p> Conclusions <p>Statin therapy independently predicts an elevated risk of diabetes among patients with nephrotic syndrome. This relationship exhibits dose-dependent nonlinear characteristics, suggesting careful consideration of cumulative statin dose is warranted when managing lipid disorders in this patient population.</p>