To explore the effect and magnitude of effect of sodium‐glucose cotransporter‐2 (SGLT2) inhibitors on haematocrit and haemoglobin and the related cardiorenal benefits in patients with type 2 diabetes mellitus (T2DM), PubMed, Web of Science, CENTRAL and EMBASE were searched to identify eligible trials. This evidence concerns the gene SLC5A2 and diabetes mellitus.