Cinnamon has been used for centuries as a culinary ingredient, as a traditional medicine, and more recently considered as a complementary agent for controlling symptoms of diabetes, the metabolic syndrome, and other conditions. Prior to 2008, few studies addressed these proposed benefits of cinnamon in controlled human trials. However, during the past decade, numerous clinical trials investigated the efficacy of cinnamon supplementation in alleviating hyperglycemia, dyslipidemia, polycystic ovary syndrome, and certain inflammation-associated conditions. There is considerable variability among trials in the form, dose, and duration of cinnamon treatment, as well as in participant characteristics, all of which complicate making a synthesis of the available literature. This report briefly summarizes these studies and considers recommendations for cinnamon and human health based on the current scientific evidence.