Improving organisational health literacy ensures people can navigate, understand and use essential health information and services. However, systematic reviews have identified limited evidence for practical approaches to implementing such organisational change, particularly at a national level. This study aimed to (a) investigate the approach taken by an Australian national diabetes organisation—Diabetes Australia, as the administrator of the National Diabetes Services Scheme (NDSS)—to improve organisational health literacy over a 15-year-period and (b) examine the impact of organisational changes on the health literacy demands of health information. We performed an environmental scan, examining the websites of the NDSS, Diabetes Australia and the Australian government for reports and position statements describing organisational health literacy policies and practices between 2006 and 2021. The Patient Education Materials Assessment Tool (PEMAT) was applied to consecutively published NDSS diabetes self-care fact sheets (n = 20) to assess changes in the health literacy demands (understandability and actionability) of these fact sheets over the same period. We identified nine policies resulting in 24 health literacy practice changes or projects between 2006 and 2021, applied using a streamlined incremental approach and group reflexivity. The incremental approach focused on (1) increasing audience reach, (2) consistency and branding, (3) person-centred language and (4) the understandability and actionability of health information. The PEMAT scores of fact sheets improved between 2006 and 2021 for understandability (53% to 79%) and actionability (43% to 82%). Diabetes Australia’s information development process leveraging national policies, employing an incremental approach and group reflexivity has improved the health literacy demands of diabetes information and serves as a template for other organisations seeking to improve their organisational health literacy.