AimThe purpose of this study was to evaluate the effect of 50 and 100 mg doses of green cumin essential oil on glycemic and inflammatory indices in patients with diabetes type II.MethodIn this randomized double-blind placebo-controlled clinical trial, subjects were divided into three groups after selecting them randomly according to the inclusion criteria: 1 – Cuminum cyminum capsule (100 mg/day,n = 33), 2 – C. cyminum capsule (50 mg/day, n = 33), and 3 – placebo (n = 33). Before and after 8 weeks of intervention, a blood sample was taken.FindingsThe findings demonstrated that the mean of the FBS, glycosylated hemoglobin (HgA1c) and the serum levels of insulin were significantly decreased and insulin sensitivity (HOMA-IR) was significantly increased in the groups receiving the 100 mg supplement (P < 0.001) and 50 mg supplement, but these indices were increased in the placebo group. The mean serum levels of TNF-α and hsCRP were significantly decreased, and serum levels of adiponectin was significantly increased at the end of the study in the groups receiving 100 mg (P < 0.001) and 50 mg (P = 0.008) supplement as well as in the group who received the placebo. There were no significant change in HOMA-B and QUICKI as insulin resistance parameters.Discussion and conclusionAdministering C. cyminum supplement in patients with diabetes type II may decrease the serum levels of insulin, FBS, and glycosylated hemoglobin and also the inflammatory indices of TNF-α and hsCRP and increased the serum levels of adiponectin. In addition it may control the complications of diabetes type II in these patients.