The incidence of cystic fibrosis-related diabetes (CFRD) has increased, since the life expectancy of cystic fibrosis (CF) patients continues to improve. CFRD increases the mortality in patients, because of the negative impacts of CFRD on pulmonary functions. Knowledge of the pathogenesis and course of the disease is essential to administer the appropriate therapy. A thirty-one-year-old CFRD patient, who had hypoglycemia and weight loss under the calorie restriction diet and basal insulin therapy, was admitted to the Endocrinology Department for revision of her therapy. A high-calorie diet considering increased energy demand and multiple insulin injections according the carbohydrate counting were administered to the patient. She gained weight and target blood glucose levels were achieved as a result of this therapy. We present the first case with CFRD followed in our clinic with the review of the literature about the pathogenesis, course and therapy of this disease to draw attention to a special kind of diabetes, which we will encounter more frequently.