Endocrine Abstracts

Renal glucosuria is a rare cause of hypoglycaemia. We describe an 18-year-old female who presented with a 2-year history of recurrent episodes of light-headedness and headaches. Glucometer readings during these symptoms demonstrated hypoglycaemia as low 2.1 mmol/l. She also had a 4-year history of recurrent urinary tract infections. Multiple dipstick urinalyses with GP demonstrated glucosuria, which was quantified with a 24-hour urinary glucose elevated at 4g/1.73m ² /day. Fasting glucose was 4.7 mmol/l and HbA1c 34 mmol/mol. Baseline pituitary function was normal and Fanconi syndrome was excluded (normal urinary phosphate, uric acid and amino acids). She underwent a 5-hour oral glucose tolerance test for evaluation of hypoglycaemia (results shown in Table 1). This demonstrated hypoglycaemia with an exaggerated insulin response to the glucose load. Symptoms provoked during hypoglycaemia at 180 min corresponded with the light-headed symptoms she had described over the previous 2 years. Genetic testing with mitochondrial genome and glycogen storage disorder panel identified a heterozygous novel missense mutation in the SLC5A2 gene, variant c.394C>A, p.(Arg132Ser). The subject’s mother and sister did not demonstrate glucosuria, and no further family members are available for screening. The subject responded to a low glycaemic-index diet. This case describes renal glucosuria with hypoglycaemia secondary to a novel mutation in the SLC5A2 gene, which encodes for sodium-glucose cotransporter-2 (SGLT2) protein. The association of renal glucosuria and hypoglycaemia has been rarely described, with only 3 case reports in the literature.