In healthy people, cocoa-derived flavanols (CF) improve blood pressure (BP). This meta-analysis investigates whether CF also affect BP in diabetic patients. PubMed, Web of Science, and Embase were consulted to retrieve eligible randomized controlled trials. A random-effects model and the Grades of Recommendation, Assessment, Development and Evaluation (GRADE)-approach were used for analyses and quality of evidence respectively. Of 267 citations, 11 trials were identified, studying either type 2 diabetic populations only (subgroup A) or type 2 diabetic patients plus non-diabetic subjects with increased cardiovascular risk (subgroup B1) or type 1 plus type 2 diabetic patients (subgroup B2). Mid/long-term CF consumption decreased BP slightly, however, only reaching statistical significance for diastolic BP in subgroup B1 (-1.89 mmHg, 95% CI: − 3.24, − 0.54, I2 = 55%). Considerable heterogeneity between studies and low quality of evidence caused poor quality evidence of minimal effects of CF ingestion on BP in diabetic patients.