To confirm that the glycosuria was due to a reduced threshold for glucose reabsorption in the kidney in these family members and not only a corollary of elevated plasma glucose we compared the prevalence of glycosuria between individuals with normal and abnormal glucose tolerance (IGT or T2D) and between those with the SLC5A2 mutations (6 of whom also had abnormal glucose tolerance). Here, SLC5A2 is linked to type 2 diabetes mellitus.