Caesalpinia bonducella contain flavonoid, tanin, saponin which has antidiabetic activity. The aim of this study was todetermine that the Caesalpinia bonducella seed extract orally reduces post-prandial blood glucose level and prevent thereduction of fasting insulin level in diabetic male albino rats (Rattus norvegicus). This study was a true experimentalwith pre-test post-test control group design using 24 male albino rats. All samples were induced with streptozotocinwhich caused the destruction of β cell and nicotinamide which protected the β cell from destructions of that thepancreatic β-cell was not destructed entirely. The selected samples were divided into three groups: the control negativegroup was given distilled water (P0), the control positive group was given glibenclamide (P1), and the treatment groupwas given ethanolic extracts of Caesalpinia bonducella seed 500mg/kg body weight (P2). Blood glucose and plasma insulin measurements were taken after 14 days of treatment. The result showed that the post-prandial blood glucose level of treatment group (P2) was decreased significantly, from 232,63±10,31 mg/dl to 185,50±16,00 mg/dl (P<0.001) whereas in P0 group, post-prandial blood glucose level was rising significantly from 223,75±17.03 mg/dl to 267,25±17,56 mg/dl (p<0.001). In P1 group, the reduction of post-prandial blood glucose level was bigger compare to P2 group, which was from 228,50±11,55 mg/dl to 115,88±10,23 mg/dl (p<0.001). Post test fasting insulin level of P2group was significantly different compare to other group (p<0.05). The administration of Caesalpinia bonducella seedextract increased the fasting insulin level although did not significant statistically (p>0.05) whereas the other groupshowed the reduction of fasting insulin level (p<0.05). It can be concluded that the administration of Caesalpiniabonducella seed extract orally reduced post-prandial blood glucose level and prevent reduction of fasting plasma insulin level in diabetic male albino rats.