This study evaluated the role of health literacy (HL) in the self-management of diabetes. A literature search was conducted in electronic databases and studies were selected using precise eligibility criteria. A meta-analysis was conducted to estimate the HL adequacy rate, factors affecting the adequacy of HL and correlations between HL and diabetes self-management variables. Thirty-three studies were included in the analysis. The HL adequacy rate was 67% (95% confidence interval (CI) 57, 76). Compared with patients with inadequate HL, patients with adequate HL were younger (mean difference -5.2 years; 95% CI -7.2, -3.2; P<0.00001), more likely to have a high school or higher level of education (odds ratio (OR) 8.39; 95% CI 5.03, 13.99]; P<0.00001) and were less likely to belong to a low-income group (OR 0.36; 95% CI 0.23, 0.56; P<0.00001). HL was positively correlated with self-monitoring (r=0.19; 95% CI 0.11, 0.27; P<0.00001), dietary and physical care (r=0.12; 95% CI 0.07, 0.18; P=0.009), diabetes knowledge (r=0.29; 95% CI 0.09, 0.45; P<0.001), self-efficacy (r=0.28; 95% CI 0.15, 0.41; P<0.00001), self-care (0.24; 95% CI 0.16, 0.31; P<0.00001), formal education (r=0.35; 95% CI 0.18, 0.53; P<0.00001) and social support (r=0.2; 95% CI 0.07, 0.33; P<0.00001). Patient age (r=-0.28; 95% CI -0.39, -0.17; P<0.00001) was inversely correlated with HL. In conclusion, 67% of diabetes patients had adequate HL, with a higher rate among better educated and higher income groups. HL had a statistically significant but weak positive correlation with diabetes self-management variables.