Aim To summarize, critically review, and interpret the evidence related to the systematic reviews on health literacy (HL) amongst type 2 diabetes mellitus (T2DM). Methods The methodology for this study consisted of a systematic review of systematic reviews, using the PRISMA statement and flowchart to select studies, and searching on PubMed, CINAHL, Scopus, and Cochrane. The search covered the period between January 2006 and June 2016. Results From the 115 identified record by the queries, only six systematic reviews were included, following a quality evaluation using AMSTAR. The included systematic reviews content was analyzed by the independent work of two authors, using a narrative synthesis approach.The findings of this study (i.e., main themes) are areas of consensus and gaps in knowledge. Areas of consensus are HL definition, HL measurement tools, and the relationship between T2DM patient knowledge (or literacy) and his/her HL. The gaps in knowledge were the assessment of the relations between HL and health outcomes and self-efficacy, the gender differences, the effectiveness of interventions to improve HL, the cost-effectiveness study of interventions to improve HL, and the understanding of the influence of organizational environment on HL. Conclusion This review provides a current state of knowledge to address clinical practice and research proposals. HL could be useful to personalize patients’ follow-up and it should be routinely assessed in its three dimensions (i.e. functional, interactive and critical) to enhance patients’ ability to cope with clinical recommendations. Future research should be mainly aimed to test the effectiveness of evidence-based interventions to improve HL amongst T2DM patients.
Keywords Health literacy · Type 2 diabetes mellitus · Diabetes mellitus · Systematic review · Diabetes knowledge · Health outcomes