Ripe and unripe tomatoes have been implicated in prevention of chronic diseases such as cancer probably due to their antioxidant, antibiotic, antifungal and anti-inflammatory properties. Problem statement: This study was designed to investigate whether ripe and unripe tomatoes will have hypoglycaemic effect in a chronic disease such as diabetes mellitus that has been characterized with hyperglycaemia. Approach: Twenty albino Wistar rats were divided into 4 groups (2 control and 2 test groups) of 5 rats each. The normal and diabetic control groups were given citrate buffer (intraperitoneally) and normal rat chow and 65 mg kg −1 streptozotocin (intraperitoneally) and normal rat chow respectively. The test groups were given 65 mg kg −1 streptozotocin via intraperitoneal route and either a mixture of ripe or unripe tomato and normal rat chow. In all groups, the blood samples were obtained at the tail vein of the animals and the fasting blood glucose level were monitored and determined on the 1st, 3rd and 14th day of consumption of different feed combinations. Results: There was significant difference in blood glucose level in animals fed on ripe and unripe Lycopersicon esculentum (tomato) compared to the normal and diabetic control groups on the 3rd and 14th day without significant difference on the 1st day. Conclusion: Both high-lycopene ripe tomato and high-tomatine unripe tomato have hypoglycaemic effect in diabetic mellitus at short period of dietary intake therefore this suggest that consumers may benefit by not only eating high-lycopene ripe tomatoes, but also hightomatine unripe tomatoes.