To investigate the clinical diagnostic characteristics and molecular genetic mechanisms of Gitelman syndrome(GS) combined with reversible glucose metabolism disorder.

A retrospective analysis was conducted on the clinical data of a GS patient with reversible glucose metabolism disorder who was admitted to the Endocrinology and Metabolism Department of the Ninth People′s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine on July 20, 2020, and the relevant literature was reviewed.

A 31-year-old man was admitted with severe hyperglycemia (random blood glucose >33 mmol/L, HbA1c 12.6%), profound hypokalemia (2.40 mmol/L), and hypomagnesemia (0.41 mmol/L). The levels of supine plasma aldosterone (251.61 ng/L), upright plasma renin activity [5.83 ng/(mL·h)], and urinary aldosterone (22.31 μg/d) were mildly elevated, whereas the aldosterone to renin ratio (ARR) was normal. His blood pressure and 24-hour urinary calcium(0.92 mmol) were within normal limits, and no metabolic alkalosis was observed, with no evidence of adrenal, thyroid, or catecholamine abnormalities. Whole-exome sequencing combined with Sanger sequencing validation identified a compound heterozygous variation in the SLC12A3 gene (IVS7EX8B and D486N). Following potassium and magnesium repletion combined with antidiabetic therapy, his clinical symptoms, blood glucose, and electrolyte levels improved significantly. Notably, all glucose-lowering agents were successfully withdrawn two months post-discharge, and normal glycemic control was steadily maintained (fasting glucose ≤6.0 mmol/L; postprandial glucose, 5.0-6.0 mmol/L). At the 1-year follow-up, HbA1c was 5.3%, and serum potassium ranged from 2.5 to 3.5 mmol/L.

Genetic testing is of great value for early diagnosis and phenotypic evaluation. Patients with GS are prone to impaired glucose metabolism. Timely potassium and magnesium repletion can improve glycemic control and even allow discontinuation of glucose-lowering medications.