Type 2 diabetes mellitus (T2DM) is a major global public health concern, prompting the ongoing search for new treatment options. Medicinal plants have emerged as one such alternative. Our objective was to evaluate the antidiabetic effect of an extract from the leaves of Passiflora ligularis (P. ligularis). For this purpose, T2DM was first induced in mice using a high-fat diet and low doses of streptozotocin. Subsequently, an aqueous extract or an ethanolic extract of P. ligularis leaves was administered for 21 days. The following relevant results were found: fasting blood glucose levels were reduced by up to 41%, and by 29% after an oral glucose overload. The homeostasis model assessment of insulin resistance (HOMA-IR) was reduced by 59%. Histopathologically, better preservation of pancreatic tissue was observed. Regarding oxidative stress parameters, there was an increase of up to 48% in superoxide dismutase (SOD), an increase in catalase (CAT) activity by 35% to 80%, and a decrease in lipid peroxidation (MDA) by 35% to 80% in the liver, kidney, or pancreas. Lastly, regarding the lipid profile, triglycerides (TG) were reduced by up to 30%, total cholesterol (TC) by 35%, and low-density lipoproteins (LDL) by up to 32%, while treatments increased high-density lipoproteins (HDL) by up to 35%. With all the above, we can conclude that P. ligularis leaves showed antihyperglycemic, hypolipidemic, and antioxidant effects, making this species promising for the treatment of T2DM.