This systematic review and meta-analysis investigated the association of diabetes and glycemic control with myocardial fibrosis (MF). MF is associated with an increased risk of heart failure, coronary artery disease, arrhythmias, and death. Diabetes may influence the development of MF, but evidence is inconsistent. The authors searched EMBASE, Medline Ovid, Cochrane CENTRAL, Web of Science, and Google Scholar for observational and interventional studies investigating the association of diabetes, glycemic control, and antidiabetic medication with MF assessed by histology and cardiac magnetic resonance (ie, extracellular volume fraction ECV% and T time). A total of 32 studies (88% exclusively on type 2 diabetes) involving 5,053 participants were included in the systematic review. Meta-analyses showed that diabetes was associated with a higher degree of MF assessed by histological collagen volume fraction (n = 6 studies; mean difference: 5.80; 95% CI: 2.00-9.59) and ECV% (13 studies; mean difference: 2.09; 95% CI: 0.92-3.27), but not by native or postcontrast T time. Higher glycosylated hemoglobin levels were associated with higher degrees of MF. Diabetes is associated with higher degree of MF assessed by histology and ECV% but not by T time. In patients with diabetes, worse glycemic control was associated with higher MF degrees. These findings mostly apply to type 2 diabetes and warrant further investigation into whether these associations are causal and which medications could attenuate MF in patients with diabetes.