Background <p>Type 2 Diabetes Mellitus (T2DM) is characterized by insulin resistance and/or pancreatic β-cell dysfunction and is a leading global health burden.</p> Objective <p>This systematic review aims to review and synthesize clinical trial data on the effects of cocoa flavonoids on glycemic control, lipid metabolism, and inflammatory responses in individuals with T2DM.</p> Methods <p>A systematic search was conducted in MEDLINE, Embase, Cochrane, Scopus, VHL, LILACS, and SciELO (November 2024), without publication date restrictions. Eligible studies included clinical trials in adults or older individuals with T2DM assessing glycemia, insulin, markers of glycemic homeostasis, lipid profile, and inflammatory biomarkers. The Cochrane Risk of Bias tool was used to assess study quality. This review was registered in PROSPERO under CRD42021235147.</p> Results <p>Seven clinical trials met the inclusion criteria. Two studies reported significant reductions in fasting blood glucose after 8&#xa0;weeks of daily intake of cocoa products and by-products (e.g., 25–30&#xa0;g of dark chocolate). One of these also showed a reduction in HbA1c, and another reported reductions in CRP, IL-6, and TNF-α. Three studies described increases in HDL cholesterol. However, most studies showed no significant effects on glycemic or inflammatory markers, and four had high overall risk of bias.</p> Conclusions <p>Evidence from a small number of heterogeneous studies, over half of which presented a high risk of bias, suggests that cocoa products and by-products may provide modest metabolic benefits for individuals with T2DM. Given the limited number of positive outcomes, these findings should be interpreted with caution and confirmed by well-designed clinical trials to determine efficacy and optimal intake protocols.</p>