Background: This case reports Gitelman syndrome combined with type 2 diabetes caused by a new homozygous mutation in the SLC12A3 (c.1567G>A) gene. This is the first report in Asia. The patient's family has 10 biological siblings. We have further tested the SLC12A3 gene in the patient's family, revealing the genetic characteristics.Case presentation: The main symptoms of this patient were long-term dizziness, weakness of the limbs, insomnia and anxiety, laboratory examinations found elevated

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... ing blood sugar, hypomagnesemia, increased urinary calcium, slightly increased RAAS activity, and hypokalemia that is difficult to correct. Potassium and magnesium were supplemented by oral potassium chloride sustained-release tablets and potassium-magnesium aspartate oral solution. The patient controlled blood glucose only through exercise and diet. After three months, the patient still occasionally experienced dizziness, the symptoms of fatigue were significantly relieved, the serum potassium was slightly decreased, the serum magnesium was normal, and the patient's fasting blood glucose was slightly increased. In family tracing, the heterozygous mutation site of SLC12A3 (C.1567g >A) was detected in the patient's mother, two sisters and one brother, but no obvious symptoms were presented. We followed up their situation through telephone follow-up.Conclusion: In this case, we found that Gitelman syndrome homozygous variants had more severe clinical phenotypes, and that hypokalemia and hypomagneemia were more difficult to correct. When serum potassium and magnesium concentrations tended to be normal, patients had better glycemic control. Some SLC12A3 mutation carriers may have atypical clinical symptoms and normal serum potassium, which is worthy of clinical attention.