Background: For an effective treatment of patients, quality-assured safe implementation of drug therapy is indispensable. Fasting during Ramadan, an essential religious practice for Muslims, affects Muslim diabetics' drug use in a number of different ways. Objectives: Ethical problems arising from fasting during the month of Ramadan for practicing Muslim patients are being discussed on the basis of extant research literature. Relevant conflicts of interest originating in this situation are being analysed from an ethical perspective. Material and methods: A number of databases have been searched systematically in view of the stated objectives to identify relevant studies. Starting point for this review are the following questions: What information is available regarding the fasting behaviour of Muslim diabetics during Ramadan? What kind of ethical problems can be identified in the context of this religious practice? Results: The present review established a number of problems concerning medication adherence and drug use of practising Muslim diabetics during Ramadan, notably insufficient compliance, reduced frequency of consultations with their doctor, and inadequate, not sufficiently goal-oriented doctor-patient conversations about fasting. Conclusions: Deficiencies in medical as well as religious knowledge about fasting in Ramadan and a lack of sensitivity have been found among Muslim patients as well as among doctors. Compliance management and drug use in this area can be improved by effective, goal-oriented action plans and projects through which linguistic and cultural barriers can be addressed.