Intermittent fasting is increasing in popularity as a means of losing weight and controlling chronic illness. Patients with diabetes mellitus, both types 1 and 2, comprise about 10% of the population in the United States and would likely be attracted to follow one of the many methods of intermittent fasting. Studies on the safety and benefits of intermittent fasting with diabetes are very limited though, and health recommendations unfortunately today arise primarily from weight loss gurus and animal studies. Medical guidelines on how to manage therapeutic intermittent fasting in patients with diabetes are non-existent. The evidence to build such a clinical guideline for people with a diabetes diagnosis is almost non-existent, with just one randomized trial and several case reports. This article provides an overview of the available knowledge and a review of the very limited pertinent literature on the effects of intermittent fasting among people with diabetes. It also evaluates the known safety and efficacy issues surrounding treatments for diabetes in the fasting state. Based on those limited data and a knowledge of best practices, this paper proposes expert-based guidelines on how to manage a patient with either type 1 or 2 diabetes who is interested in intermittent fasting. The safety of each relevant pharmaceutical treatment during a fasting period is considered. When done under the supervision of the patient’s healthcare provider, and with appropriate personal glucose monitoring, intermittent fasting can be safely undertaken in patients with diabetes.