Introduction: The Patient Assessment on Chronic Illness Care (PACIC) was developed to assess patients’ perspectives on the alignment of primary care to the chronic care model. The Malay PACIC has been validated; however, Malaysia is a multicultural society, and English is spoken by many Malaysians and expatriates. We sought to validate the English version of the PACIC among patients with diabetes mellitus in Malaysia, as Malaysians may interpret a questionnaire that was originally developed for Americans in a different way. Method: This study was conducted between November and December 2016 at two primary care clinics that offered integrated diabetes care at the time. These sites were selected to assess the discriminative validity of the PACIC. Site 1 is a Malaysian Ministry of Health-run primary care clinic while site 2 is a university-run hospital-based primary care clinic. Only site 1 annually monitors patient performance and encourages them to achieve their HbA1c targets using a standard checklist. Patients with diabetes mellitus who understood English were recruited. Participants were asked to fill out the PACIC at baseline and two weeks later. Results: A total of 200 out of the 212 invited agreed to participate (response rate=94.3%). Confirmatory factor analysis confirmed the 5-factor structure of the PACIC. The overall PACIC score and the score in two of the five domains were significantly higher at site 1 than at site 2. The overall Cronbach’s alpha was 0.924. At test-retest, intra-class correlation coefficient values ranged from 0.641 to 0.882. Conclusion: The English version of the PACIC was found to be a valid and reliable instrument to assess the quality of care among patients with diabetes mellitus in Malaysia.