A 4-week Randomized, Double-Blind, Placebo-Controlled Clinical Trial on the Use of Grape Seed Extract for Reducing Plasma Glucose, Lipid Profile, and Blood Pressure in Patients with Type 2 Diabetes Mellitus

: Diabetes mellitus (DM) is a common chronic disease that can significantly reduce life expectancy due to its complications. Grapes (Vitis vinifera L.) and their byproducts, including grape seeds, have been used worldwide for the treatment of various ailments. This clinical trial investigated the effect of grape seed extract (GSE) on fasting blood sugar (FBS), lipid profile (including total cholesterol, high-density lipoprotein [HDL], low-density lipoprotein [LDL], and triglycerides [TG]), and systolic blood pressure (SBP) and diastolic blood pressure (DBP) in patients with type 2 diabetes mellitus (T2DM). A total of 74 patients with T2DM were divided into two groups, including 38 patients in the treatment (GSE) group receiving 263.2 mg of GSE (standardized to 250 mg proanthocyanidin) twice daily and 36 patients in the placebo (control) group receiving 263.2 mg of the placebo twice daily for 30 days. At the end of the intervention, a statistically significant decrease was observed in SBP (from 125.83 ± 13.39 in the placebo group to 121.94 ± 7.49 in the treatment group, P = 0.002) and FBS (from 144.75 ± 30.82 in the placebo group to 129.87 ± 31.79 in the treatment group, P = 0.001). However, there were no significant changes in total cholesterol, HDL, LDL, TG, and DBP between the two groups. The use of Iranian GSE for a short period might lead to lower FBS and SBP. Therefore, GSE might play a significant role in improving blood pressure and fasting blood glucose levels in patients with T2DM.