Diabetes is an increasingly prevalent disease state with a global impact. It is important that effective and cost-efficient methods be developed to treat this disease state. Zucker diabetic fatty rats, an animal model of type 2 diabetes, were treated with montbretin A (MbA), a selective human pancreatic α-amylase inhibitor, isolated from the corms of the Crocosmia crocosmiiflora plant that may have potential as a glucose-lowering agent. The study purpose was to determine if MbA was an orally effective treatment for diabetes. The effect of MbA was compared to a current clinical treatment modality, acarbose that is associated with gastrointestinal side effects known to affect patient compliance. MbA and acarbose were administered daily in the drinking water. Body weight and fluid intake were measured daily to calculate dose consumption. Plasma glucose levels were determined twice weekly in both the fed and fasted state. At termination samples were collected to assess increased risk of secondary complications related to diabetes and oxidative stress. There was no effect of either MbA or acarbose treatment on insulin levels. Plasma glucose levels were significantly lower following MbA treatment in the ZT group which persisted throughout the study period (day 49: 12.1 ± 1.2 mM). However, while there was an initial decrease in plasma glucose levels in the acarbose-treated fatty group, this effect was not sustained (day 49: 20.6 ± 1.3 mM) through to termination. MbA improved the oxidative status of the fatty diabetic animals as well as attenuated markers for increased risk of cardiovascular complications associated with diabetes. This study demonstrated that, at a lower dose as compared to acarbose (10 mg/kg/day), chronic oral administration of MbA (7.5 mg/kg/day) was an effective glucose-lowering agent in the treatment of type 2 diabetes.