The blood glucose level of the body tends to increase slightly after the age of 50. The coriander (Coriandrum sativum L) is a member of the Apiaceae family and it grows in a wide range conditions and can be used as antidiabetic. The purpose of this study was to determine the effect of coriander water extract on the blood sugar levels of white rats (Rattus norvegicus strain wistar). The method of this study involved experimental animals, specifically 20 Rattus norvegicus strain wistar ranging from 150-200grams with an age between 2–3 months. The mice were injected with an alloxan solution to induce a diabetic condition and then they were divided into four groups and treated. The treatments were 0.5% Na CMC, glibenclamide 0.45mg/Kg b.w, coriander extract of 100mg/Kg b.w and coriander extract of 200mg/Kg b.w for 15 days. The blood glucose level of the mice was measured on days 0, 1, 5, 10 and 15. The results showed that the 0.5% CMC placebo had no effect in terms of reducing the glucose level of the rats, Glibenclamide 0.45mg/Kg b.w had an effect in terms of reducing the blood glucose level, as did coriander extract 100mg/Kg b.w and 200mg/Kg b.w among the alloxan-diabetic mice.