Introduction. Gitelman Syndrome (GS) is a genetic tubulopathy frequently linked with insulin resistance. The possibility of developing Diabetes Mellitus (DM) in GS increases with the causes of insulin resistance. Hypokalemia is one of the most common electrolyte disorders in GS, and most diabetic drugs can cause hypokalemia. Considering this dilemma, we presented a DM treatment experience in a GS case. Case presentation. A 47-year-old male GS patient with a potassium-rich diet complained of weight loss and dry mouth for 2-3 months. The laboratory tests revealed a higher HbA1c level, as high as 11.8%. The remaining abnormal laboratory test results (hypokalemia, hypomagnesemia, metabolic alkalosis) indicated a patient with GS. The patient was placed on a metformin+gliclazide-based treatment. Oral potassium and magnesium supplementation were started for the patient whose hypokalemia increased in the first control, and the potassium dose was doubled in the third control. In the first-month follow-up visit, it was observed that the blood potassium level was improved, and hyperglycemia was optimized. Conclusion. In brief, any treatment for DM can be selected in GS patients with DM by performing frequent electrolyte monitoring. Like our case, oral potassium supplementation was adequate for the metformin + gliclazide combination-coincidence hypokalemia.