Basic sciences attract specific attention of medical professionals worldwide. Medical genetics can bridge between clinical observations and basic sciences via specific focus on the molecular aspects of diseases. Importance of genetic counseling as the main part of management of inherited disorders should be realized by all physicians. This paper provides genetic counseling essentials with main focus on the endocrinopathies and metabolic disorders especially diabetes mellitus and its complications. This paper may help the endocrinologists to have more attention on these rules for referring rare familial or syndrome cases. High ethnicity variations and high rate of consanguineous marriage in Iran as well as increase in the incidence and prevalence of such disorders highlight the importance of molecular studies of such disorders in our country.