Objective: To evaluate serum magnesium levels in patients with early chronic kidney disease (CKD) and determine whether magnesium independently predicts insulin resistance. Methods: This analytical cross sectional study was conducted at Jinnah Postgraduate Medical Centre (JPMC), Karachi, from January to August 2025. A total of 180 adults with CKD stages 1–3 were enrolled through consecutive sampling. Fasting blood samples were analyzed for serum magnesium, fasting glucose, insulin, creatinine, and HbA1c. Estimated glomerular filtration rate (eGFR) was calculated using the CKD-EPI equation. Insulin resistance was assessed using the Homeostasis Model Assessment of Insulin Resistance (HOMA-IR). Intergroup comparisons were performed using one-way ANOVA, and associations were assessed using Pearson correlation and multivariate linear regression analysis. Results: Serum magnesium levels declined significantly with advancing CKD stage (2.12±0.21 mg/dL in stage 1, 1.98±0.19 in stage 2, and 1.82±0.17 in stage 3; p<0.001). In contrast, HOMA-IR increased progressively (2.1±0.8, 2.8±1.1, and 3.6±1.3, respectively; p<0.001). Serum magnesium showed a significant inverse correlation with HOMA-IR (r = −0.52, p<0.001) and fasting insulin (r = −0.49, p<0.001), and a positive correlation with eGFR (r = 0.45, p<0.001). After djustment for age, BMI, HbA1c, and eGFR, serum magnesium remained an independent predictor of insulin resistance (β = −0.38, p<0.001). Conclusion: Lower serum magnesium levels are independently associated with increased insulin resistance in early CKD. Magnesium may serve as a useful metabolic marker and potential therapeutic target in this population