Healthy male Wistar rats (180g ±20g) were used. The animals were received from the Animal House of Physiology Department, Ladoke Akintola University of Technology, Ogbomoso, Oyo State, Nigeria. Rats were housed in a plastic cage (8 rats per cage) under controlled conditions of temperature (25±2°C), humidity (45% + 5%) and light (12 h light/dark cycles). The animals were fed with rat pellets (Premier Feed Ltd. Ibadan) and water ad libitum and were acclimatized for 1weeks prior to the initiation of the experiment. All procedures were approved by the Animal Care Committee of Ladoke Akintola University of Technology. All experimental protocols and handling of the animals were following the Guide for the Care and Use of Laboratory Animals .
2.2 Plant materials
Anacardium occidentale nuts were obtained from plants grown at Ladoke Akintola University of Technology (LAUTECH) farm, Ogbomoso, Oyo state. The plant was identified and authenticated by Dr A. T. J. Ogunkunle, Biology Department, Ladoke Akintola University of Technology, Ogbomoso, Oyo state, and a voucher specimen number of LH0 533 was given.
2.3 Plant extraction
The nut of Anacardium occidentale plant was sun-dried at room temperature in the laboratory, powdered and stored in airtight container. The powdered nut of Anacardium occidentale was extracted with 95% ethanol in the Soxhlet apparatus .
2.4 Phytochemical Analysis
Anacardium occidentale nut extracts were subjected to preliminary phytochemical screening for the presence of alkaloids, quinines, resins, tannins, fixed oils, flavonoids, fats, saponins, phenolic compounds, Proteins and carboxylic acids using the procedures outlined by Sofowora; Trease and Evans [22,23].
2.5 Acute toxicity test
Acute toxicity test was carried out according to the modified Lorke's method  using a total of 12 rats. At the initial phase, the rats were assigned randomly into three groups of 3 rats each. The rats in each group were administered an intraperitoneal injection of extract at 10, 100, and 1000mg/kg. Their body weight was observed for signs of toxicity and death in the first 24hours. In the second phase, another set of rats were randomly assigned into four groups of one rat each and administered the Anacardium occidentale methanolic nut extract intraperitoneally, at 1600, 2900, and 5000mg/kg based on the result of the first phase. The LD50 was then calculated as the square root of the product of the maximum dose for all surviving and minimum dose for all mortality using the formula;
LD50 = (Dₒ X D₁₀₀)
2.6 Experimental induction of diabetes
Diabetes was induced through a single intraperitoneal injection of (50 mg/ kg b.w.) freshly prepared streptozotocin (STZ) in 0.1 M citrate buffer (pH = 4.5) to overnight fasted rats . To prevent the initial drug induced hypoglycemic death, diabetic rats were permitted to drink a 20% glucose solution overnight. The blood glucose level was measured after three days, and rats with glucose levels >200 mg/dL were considered as diabetic. Control rats however injected with 0.2 mL of the vehicle (0.1 M citrate buffer, pH 4.5) alone.
2.7 Experimental Design
A total of 40 experimental rats were used to assess the effect of the nut extracts on the experimental rats: 32 STZ induced diabetic rats plus 8 normal control rats. Animals were divided into five (5) major groups and housed under controlled environmental conditions. Rats were divided into the following groups:
Group 1: Control (CON)
Group 2: STZ induced diabetic rats (STZ)
Group 3: STZ induced diabetic rats + nut extract Anacardium occidentale (100 mg/kg b.w.)
Group 4: STZ induced diabetic rats + nut extract Anacardium occidentale (200 mg/kg b.w.)
Group 5: STZ induced diabetic rats + 2mg/kg b.w. Glimepiramide (GMP)
2.8 Assessment of Fasting Plasma Glucose Levels and Body Weight Measurement
The body weight measurement and fasting plasma glucose levels were assessed before and during the administration of the extracts weekly, till the end of the study. The glucose level in plasma was determined by glucose oxidase/peroxidase method as described by  using a digital glucometer and test strips (Accu-Chek Advantage, Roche Diagnostic, Germany)
2.9 Biochemical Parameters
At the end of the experimental treatment, after 12h fasting, the animals were anaesthetized with ketamine-75mg/kg and xylazine-20mg/kg intraperitoneal injection. The unconscious animals were sacrificed by cervical dislocation and the hearts were exposed by thoracotomy. The fasting blood was collected via cardiac punctured into heparinized tubes, centrifuged at 13000 rpm for 5 mins, and the plasma was then retrieved. The plasma determination of plasma total cholesterol (TC), triglycerides (TG) and HDL-cholesterol, was done using a commercial Diagnostic Kit (Genzyme Diagnostics, MA. USA).
Antioxidant enzyme activities in the plasma were assayed using commercial kits: Serum GSH was measured based on the method described by . Serum MDA, SOD, and GPx levels were measured by enzyme-linked immunosorbent assay (ELISA) methods using Rat MDA, SOD, and GPx Elisa Kit (Elabscince, China).
Markers of kidney function (blood urea nitrogen (BUN), plasma creatinine, and uric acid) were determined by using the commercially kits from Siemens Health Care Diagnostics.The liver biomarkers such as Aspartate aminotransferase (AST), Alanine aminotransferase (ALT), Alkaline phosphatase (ALP), Total protein (TP), and Albumin were assayed in plasma spectrophotometrically by standard automated techniques according to the procedures described by the manufacturers.
2.10 Statistical analysis
Data statistical analysis was carried out using SPSS, Version 21 software. The results were expressed as mean ± SEM, and the statistical difference was evaluated using one-way analysis of variance (ANOVA) followed by Bonferroni post hoc test. Data were considered statistically significant at p less than 0.05 (p<0.05)