Mucormycosis, previously known as zygomycosis, is an invasive fungal infection that despite surgical and antifungal treatment remains to be associated with high mortality. We present two cases of mucormycosis associated with first episode of diabetes ketoacidosis. The first patient had no known previous history of diabetes mellitus, and presented initially with acute symptoms of hyperglycaemia, and subsequently developed multiple cranial nerve palsies. Surgical debridement was attempted, and intraoperative biopsies confirmed mucormycosis, however given the extensive nature of the disease complete curative debridement was not achieved. He subsequently died less than four days after his initial presentation. The second case, was a patient with poor glycaemic control who had a history of latent autoimmune diabetes of adulthood diagnosed fourteen years earlier. He also presented to hospital with symptoms of hyperglycaemia and was determined to have diabetic ketoacidosis with unknown precipitant. Subsequently, during his admission he developed worsening facial pain and was noted to have a lesion on his hard palate. Biopsy confirmed fungal hyphae consistent with mucormycosis, and he underwent extensive surgical debridement and subtotal maxillectomy, in combination with antifungal treatment. He eventually went on to make a full recovery. Despite mucormycosis being rare, in those who develop the infection, diabetes mellitus is an underlying co-morbid condition in up to one third of cases. In patients with diabetes who develop mucormycosis, there is typically a history of uncontrolled hyperglycaemia or ketoacidosis, as well as a predilection for rhino-cerebral involvement. As these cases highlight, it is important that clinicians are vigilant of mucormycosis as a potential underlying condition and possible precipitant in individuals presenting with diabetic ketoacidosis, so that timely instigation of surgical debridement and antifungal treatment can occur.