Açaí (Euterpe ssp.) is a Brazilian berry attracting worldwide attention due to its high concentration of bioactive compounds, also known as super-fruit in some countries. Phenolic compounds, especially anthocyanins and flavonoids, are among these compounds associated with antioxidant effects and possible benefits against obesity and insulin resistance. The aim of this study was to evaluate the effect of normal-fat and high-fat diets containing a Amazonian freeze-dried açaí pulp (FAP) on the development of insulin resistance. Adult male Swiss mice (n= 40) were fed a control diet (N), control diet containing 2% FAP (NA), high-fat diet (H) and high-fat diet containing 2% FAP (HA) during 10 weeks. The dose of FAP was based on previous measurements of total bioactive compounds and antioxidant capacity. Glucose tolerance test or GTT was measured by collecting venous blood via tail vein before (0 min) and 30, 90 and 120 minutes after an intraperitoneal glucose injection (2 g/kg). The GTT aims to determine the rate of reduction of the glycemia after its cell uptake. With the same purpose, insulin tolerance test or ITT was evaluated before and 15, 30, 45 and 60 minutes after intraperitoneal insulin injection (0.75 units/kg). No differences were found among the groups supplemented with FAP in the GTT (p > 0.05, Student's t test). However, blood glucose response during the ITT showed better insulin sensitivity in the HA (p < 0.01, Student's t test) when compared to the H group. These values were similar to the normal-fat groups. The fasting blood glucose measurement corroborate this result, showing an improvement on glycemia when FAP was given to high-fat diet-fed mice. In conclusion, these findings showed that the consumption of FAP prevented peripheral insulin resistance in animals fed the high-fat diet based on the ITT and fasting blood glucose.