Patients referred for HNF1B testing present very heterogeneous phenotypes. Despite suggestive characteristics, many do not harbor mutations in HNF1B. The authors’ objective was to evaluate the clinical characteristics of probands referred for HNF1B genetic testing through a nationwide monogenic diabetes screening program. Probands tested for HNF1B mutations in the 2005-2018 period (N = 50) were identified in the Polish Monogenic Diabetes Registry, which prospectively recruits primarily pediatric patients and their families on a nationwide scale. A structured medical interview was performed with all available individuals, their parents, and/or their physicians. For each patient, HNF1B score was calculated based on available clinical information. In conclusion the authors suggested that detailed medical interview may enable more accurate patient selection for targeted genetic testing.