Background: Insulin resistance is a risk factor for multiple diseases. Resveratrol is a potent activator of sirtuin 1 (SIRT1), which is implicated in the regulation of cellular functions and energy metabolism. Activation of SIRT1 is reported to increase insulin resistance. Aim: We aimed to consider the effects of individual or combined treatment with resveratrol and metformin on serum SIRT1 activity and insulin resistance in high fructose-fed rats. Methods:   Forty male Wistar albino rats were divided into: (1) control group, (2) high fructose-fed group (HFF), (3) HFF-resveratrol-treated group, (4) HFF-metformin-treated group, and (5) HFF with combined resveratrol and metformin-treated group. Body weight, fasting blood glucose and serum insulin were measured and HOMA-IR index was calculated. Lipid profile, inflammatory and oxidative stress markers and serum SIRT1 activity were also determined at the end of the study. Results: Individual treatment with resveratrol or metformin resulted in partial significant decrease in glucose and insulin levels and HOMA-IR index, which was associated with partial significant alteration in serum lipid profile, inflammatory and oxidative stress markers levels and significantly enhanced serum SIRT1 activity. However, combination therapy of both drugs resulted in maximal improvement in all measured biochemical parameters. Conclusion: Due to their synergistic action, the combination therapy of resveratrol and metformin significantly normalized serum SIRT1 activity and insulin resistance in high fructose-fed rats.