Introduction: Diabetes self-management education (DSME) and medical nutrition therapy (MNT), provided by diabetes educators and registered dietitians respectively, considerably improve glycaemic control. However, it is unknown what interventions exist in many African countries and the impact thereof. Aim: To determine the impact of existing DSME interventions on knowledge, attitudes and practices (KAP) of adults with type 2 diabetes attending public health care facilities in Harare, Zimbabwe. Methods: A cross-sectional, researcher-administered survey was designed to assess DSME KAP at eight outpatient diabetes clinics that provide diabetes services. Participants were conveniently sampled. Associations between mean scores for knowledge, attitudes and practices were compared between characteristics of DSME interventions. Results: A total of 154 participants were recruited and divided evenly between two tertiary (n = 77) and six primary outpatient clinics (n = 77). The mean age was 61.8 years (SD ± 12.7), mean years since diagnosis with diabetes was 8.1 years (SD ± 8.3) and the majority were females (66.9%, n = 103). Most participants (90.3%, n = 139) reported receiving some DSME. Participants most frequently cited a tertiary clinic as the place where DSME was received. Fewer had consulted a dietitian (49.0%, n = 76) or diabetes educator (52.0%, n = 80). Higher levels of diabetes knowledge were observed for tertiary clinic attendees (p = 0.00), consultation with a dietitian (p < 0.01) and diabetes educator (p = 0.00). Only those who had consulted a dietitian reported better adherence to dietary guidelines (p = 0.00) and physical activity (p = 0.02) self-care behaviours. Conclusion: Dietitian-led interventions significantly improved both knowledge and practices, highlighting a need to scale up dietetic intervention, particularly in primary clinics where limited interventions occur.