SLC5A2 and diabetes mellitus: According to the standard of care, when a patient fails to reach their HbA1c target with dual therapy of metformin plus insulin, a third agent should be prescribed, such as thiazolidinedione, DPP-4 inhibitor, SGLT2 inhibitor, or GLP-1 receptor agonist.9 However, despite the wide availability of multiple classes of therapeutic agents, most insulin users have HbA1c well above the accepted targets and their diabetes is uncontrolled.13