Type 2 diabetes mellitus (T2DM) increases the risk of myocardial fibrosis, which contributes to cardiovascular complications. The prevalence of myocardial fibrosis in diabetic patients ranges from 15–62% based on a meta-analysis. Global Longitudinal Strain (GLS) assessment with Speckle Tracking Echocardiography (STE) can detect myocardial fibrosis non-invasively, with GLS < -21% to rule out fibrosis and GLS > -15% to diagnose fibrosis. Resveratrol, a natural polyphenol, is known to have cardioprotective effects; however, clinical evidence in T2DM patients is still limited to animal studies. This study aims to evaluate the effectiveness of resveratrol administration on improving cardiac fibrosis as measured by GLS in T2DM patients.This study was a double-blind randomized controlled trial in T2DM patients with GLS <21% at Dr. Mohammad Hoesin Hospital Palembang (June–November 2025). A total of 32 subjects were divided into two groups (16 each) using block permuted randomization: an intervention group and a control group for 12 weeks. Outcomes measured included changes in GLS, EF, and IVSD. Data analysis was performed using SPSS 29.Of the 40 subjects, 12 dropped out. In the analyzed subjects (14 per group), resveratrol administration for 12 weeks reduced GLS more than placebo (mean difference -1.92% vs -0.74%; p=0.006) and increased EF (mean difference +3.35% vs -4.2%; p=0.003), while IVSD did not change significantly. Resveratrol was shown to be an independent predictor of GLS and EF improvement in multivariate analysis. Mild side effects (bloating) were reported in 14.8% of resveratrol subjects.Resveratrol significantly improves GLS and EF in T2DM patients but does not affect IVSD. Resveratrol has potential as a long-term adjunctive therapy.