This integrative review sought to advance understanding of the literature pertaining to gestational diabetes mellitus (GDM) and subsequent lifestyle changes in Canadian and American populations. Gestational diabetes mellitus includes glucose intolerance identified during pregnancy and affects approximately 7% of all pregnancies worldwide or more than 200,000 cases annually. Depending upon the population studied and the diagnostic tests employed, the prevalence may range from 1% to 14% of all pregnancies. The article comprises 2 parts in which internal and external factors are discussed concerning pathophysiologic pathways and psychosocial influences. Social determinants of health affect the development of GDM. Gestational diabetes mellitus is increasing in all socioeconomic strata, particularly because of stress, sedentary lifestyle, and poor nutritional choices. Questions are raised about future research directions.