Background <p>The incidence and mortality rates of diabetes mellitus keep rising. This has partly been attributed to engagement in unhealthy lifestyles and poor knowledge on diabetes nutritional management. This study aimed to explore the knowledge on diabetes nutritional management among individuals living with diabetes in Ghana and their lifestyles prior to diagnosis.</p> Methods <p>A qualitative, exploratory, descriptive research design was employed for this study, which was conducted at a tertiary hospital. Purposive sampling was used to recruit fifteen participants who were interviewed on one-on-one basis with a semi-structured interview guide. The participants had been diagnosed for 2 to 30 years. Data collected was analysed using reflexive thematic analysis. </p> Results <p>Two main themes, knowledge on diabetes nutritional management and lifestyle prior to diabetes diagnosis, emerged from the data gathered with six subthemes. Most of the participants were knowledgeable on the healthy forms of proteins, carbohydrates, and fats to eat, and their right amounts to consume. However, more than half of the participants were involved in unhealthy eating habits such as late-night eating prior to being diagnosed with diabetes. </p> Conclusions <p>Participants were generally knowledgeable on diabetes nutritional management. Nonetheless, their lifestyles prior to diagnosis were potential contributors to the emergence of diabetes. Ignorance on the effects of unhealthy lifestyles predisposes people to diabetes. Health professionals in Ghana should roll out health education programmes to fill the knowledge gaps of the populace and individuals with diabetes on healthy eating and the need to engage in healthy lifestyles to reduce diabetes morbidity and mortality. </p>