We report a case of new-onset, nonautoimmune, nonketotic, and noninsulinopenic type 2-like diabetes in a previously normoglycemic middle-aged man debuting after vaccination against COVID-19. This was not a mild or short-lived glucose intolerance, but severe and long-standing hyperglycemia with a high glycated hemoglobin level. However, the course of the diabetes was highly atypical and surprising in that it spontaneously disappeared after a few months and did not recur despite the patient being off all antidiabetic drugs for several months and without any changes in body weight or lifestyle. The mechanisms by which severe diabetes unfolded and later remitted in this patient remain elusive. Nonetheless, and notwithstanding whether or not there was a cause-and-effect relation between the vaccinations and his diabetes, the highly atypical course of spontaneously remitting nonautoimmune diabetes lends itself to mechanistic efforts aimed at understanding the biology and pathophysiology of insulin-producing β cells in health and disease. This case report should not be construed as vaccine skepticism or deter anyone, especially with diabetes/obesity, from vaccination against COVID-19. However, it calls for increased vigilance among health care providers for unusual and unexpected metabolic effects of COVID-19 and its vaccines.