In the case described in the present study, the increase in glucose and transaminase levels, in conjunction with the other tests performed, supports the performance of screening tests for HNF-1B mutations; according to the literature, genetic testing for HNF-1B mutations is justified in non-obese diabetic subjects with slowly progressive non-diabetic nephropathy, particularly when there are renal or genital malformations or functional liver disorders, regardless of a family history of diabetes (15). This evidence concerns the gene HNF1B and diabetes mellitus.