Abstract: We report a case of a young female patient with fatigue, hypokalemia, and hyperglycemia. She had past-history of diabetes mellitus, and was admitted to hospital with a history of fatigue and hypokalemia for 5 years. The patient's examination indicated hypokalemia, hypomagnesemia, metabolic alkalosis, hypocalciuria, and SLC12A3 gene pathogenic mutation. The diagnosis was Gitelman syndrome. Potassium and magnesium supplements were given to improve the patient's fatigue. Serum potassium and magnesium were normal. The blood glucose reached standard after treatment with oral hypoglycemic drugs. This article incorporates literature review to sort out the diagnosis and treatment of Gitelman syndrome, in order to provide feasible reference for clinicians.