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 decrease life expectancy due to its complications. Grapes (Vitis Vinifera L.) and their byproducts, including seeds, have been used globally to treat various ailments. In this clinical trial, we investigated the effect of Iranian 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)], as well as systolic and diastolic blood pressure (SBP and DBP, respectively) in patients with type 2 DM (T2DM). Seventy-four patients with T2DM were divided into two groups; 38 patients in the treatment group received 263.2 mg of GSE (standardized to contain 250 mg of proanthocyanidine) twice daily, and 36 patients in the placebo group received 263.2 mg of placebo twice daily for thirty 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)]. There were no significant changes in total cholesterol, HDL, LDL, TG, and DBP between the two groups. Consuming Iranian GSE for a short duration can lower FBS and systolic blood pressure (BP), suggesting that GSE may play a key role in improving BP and fasting blood glucose in patients with T2DM.