Introduction: The bi-directional relationship between periodontitis (PD) and diabetes mellitus (DM) has been confirmed. Medical practitioners (MPs) serve an important role in relaying this information to patients. This study aimed to investigate the awareness, knowledge, attitudes and practices (KAP) in the management of DM patients with PD in primary care clinics under the Ministry of Health (MOH) of Malaysia. Methods: A self-administered questionnaire on KAP in the management of DM patients with PD was posted to 725 medical officers (MOs) and family medicine specialists (FMSs) in MOH clinics in Kedah, Terengganu, Johor and Negeri Sembilan. Collected data were tabulated and analysed using descriptive and regression analyses (simple and multiple). Statistical significance was defined as p < 0.05. Results: A total of 549 MPs responded. The majority of MPs were MOs (92.6%) and female (75.8%). FMSs had a greater awareness of PD when compared to MOs (p = 0.002). All MPs had good knowledge, except for the incorrect notion that excessive sugar causes PD (94.3%). Overall, FMSs had better knowledge when compared to MOs (p=0.026). The majority of MPs agreed that ‘they should update their knowledge on the association between systemic disease and PD’ (89.6%) and claimed that ‘it was not their responsibility to examine DM patients for PD’ (83.1%). Most MPs did not enquire or examine for PD in their DM patients. More FMSs (67.5%) referred patients to dentists compared to MOs (31.6%). Conclusion: Most MPs have sufficient knowledge on PD, but a negative attitude in the management of PD in DM patients. The reasons for not referring included workload and patients refusing referral.