In this study, the effects of grape seed extract on insulin, adiponectin and resistin levels in diabetic rats were aimed to investigate. Weight of about 300-350g 7-8 weeks 32 female Wistar Albino rats were used. Weight of about 300-350g 7-8 weeks 32 female Wistar Albino rats randomly divided into four groups of eight each: control group (C), group with diabetes (DM), grape seed extract group (GSE), diabetes mellitus and grape seed extract group (DM+GSE). The diabetic group 45 mg/kg single dose of streptozotocin was administered intraperitoneally, and the grape seed extract groups (DM+GSE and GSE) grape seed extract was given orally every day with an intragastric tube for 20 days (0.6 ml/rat). Blood samples were taken from the hearts of rat’s end of the experiment. The sera obtained were used for insulin, adiponectin and resistin analysis measured via ELISA with commercial kits. The insulin and adiponectin levels of the rats in the diabetes + grape seed extract group were found to be higher than those in the diabetes group. There was no significant change in the resistin level differences between the groups. As a result; It is possible to say that grape seed extract has an increasing effect on insulin level and adiponectin levels of diabetic rats are decreased due to diabetes and it has no significant effect on resistin levels. Detected by the positive effects of grape seed extracts, it may be useful to use for the regulating of the diabetes in human.