Abstract: Background and Objective: Preclinical testing of the use of avocado leaf extract for decreasing blood glucose level is still limited. This study aimed to analyze the effect of avocado leaf extract on fasting blood glucose level in male white rats. Materials and Methods: This study was a pre-experiment with six groups of pretest posttest with control group. The samples were male white rats (Rattus norvegicus) of Wistar strain, ±3 months old, with the treatment groups: Group 1: Feed+Streptozotocin (STZ)+10% sucrose+avocado leaf extract dose of 100 mg kg–1 b.wt., Group 2: Feed+STZ+10% sucrose+avocado leaf extract dose 150 mg kg–1 b.wt., Group 3: Feed+STZ+10% sucrose+avocado leaf extract dose 200 mg kg–1 b.wt., Group 4: Feed+STZ+10% sucrose, Group 5: Feed+STZ+10% sucrose+glibenclamide and Group 6: Feed. Data analysis used ANOVA and paired t-test with p<0.05. Results: The early fasting blood glucose level of the white rats was 58-97 mg dL–1 (p = 0.897). Giving STZ increases the fasting blood glucose level to 83-128 mg dL–1 (p = 0.136). Meanwhile, giving avocado leaf extract on day 14 decreased 68-77 mg dL–1 (p = 0.000). Group 2 experienced a significant decrease on day 7, which was 28.22 mg dL–1 (p = 0.028) and day 14, which was 31.33 mg dL–1 (p = 0.015). Conclusion: Avocado leaf extract with a dose of 150 mg kg–1 b.wt. is effective in reducing the high fasting blood glucose level in white rats.