Introduction: The study was done at the aim to assess the functionality and viability of the β cells of the streptozotocin-induced diabetic rats model following repetitive dosage of administration of ethanolic extracts of Andrographis paniculata. Materials and Methods: The diabetic rats were treated with the extracts for fourteen days and at the dose given was 500 mg/kg twice daily. The assessments were made on fasting blood glucose, insulin, and immunohistochemical aspect of β cells before and after treatment. Results: The results showed that there was a signifi cant reduction on fasting blood glucose levels in metformin, 95% and 50% ethanolic plant extracts-treated groups but on insulin level only 95% and 50% ethanolic extracts-treated groups gave a signifi cant reduction(p