Diabetes Mellitus is a chronic health problem with devastating effect that is characterized by high blood glucose levels resulting from faults or flaws in insulin production or action. The unaffordability and adverse effects of conventional drugs in the treatment and management of many diseases has spurred the interest of scientists to the use of herbal medicine to treat and manage many ailments. The purpose of this study was to investigate the prophylactic and anti-diabetic effects of Andrographis paniculata and its combination with Allium sativum on the blood glucose level and on some biochemical indices of wistar rats. The bodyweight, fasting blood glucose level, lipid profile and lipid peroxidation were determined using standard biochemical methods. All the treatment groups indicated gradual increase in their body weights which was not above normal control and significant reduction in fasting blood glucose level was also observed in all groups but with far greater reduction seen in the pretreated groups with a percentage reduction of 61.25%. The result of the lipid profile showed that varying doses of A. paniculata and A. sativum significantly reduced the LDL, TCHOL, TRIG and VLDL levels of diabetic rats. However, the pretreatment of A. paniculata gave a higher reduction in the LDL, TCHOL, TRIG and VLDL levels. The MDA level of all the test groups decreased when compared to the diabetic untreated group and the standard drug group with significant (p< 0.05) reduction seen in the groups treated with 100mg/kg and 200mg/kg of A. paniculata. The findings from this research showed that Andrographis paniculata has the potential to be used as a remedy for the treatment and management of diabetes mellitus and its complications, however pretreatment with A. paniculata is highly recommended as it gives better results in reducing the complications associated with diabetes mellitus.