Abstract
Familial renal glucosuria (FRG) is a rare genetic disease characterised by isolated glucosuria in the absence of proximal tubular dysfunction. It usually occurs due to a mutation in the SLC5A2 gene encoding the sodium-glucose cotransporter-2 (SGLT2), responsible for most of the renal glucose reabsorption. We report on a case of a patient presenting with paroxysmal glucosuria and hypercalciuria due to a novel SLC5A2 heterozygous variant. LEARNING POINTS: FRG usually presents with glucosuria but may also be associated with hypercalciuria and aminoaciduria.The amount of glucosuria is variable and can be normal in the same FRG patient because it is influenced by different glycaemia levels. This raises the question of whether the definition of FRG should be broadened to paroxysmal glucosuria.Having glucosuria does not prevent the development of insulin resistance.