In the last decade, it has become clear that gestational diabetes is a clinical entity associated with perinatal mortality and morbidity. Thus, the attention to and management of gestational diabetes during pregnancy are mandatory. In this review, results of 58 original studies (spanning the past 20 years) addressing criteria for insulin management in gestational diabetes were assessed. The level of glycemic control and its evaluation through self-monitoring of blood glucose are the foundation for ascertaining optimal pregnancy outcome. This review addresses the criteria for insulin initiation: insulin requirements, identification of the right patient, the timing for insulin initiation, and the behavioral adjustment and compliance during insulin therapy. It is recommended that patients with fasting plasma glucose on the oral glucose tolerance test (OGTT) of < 96 mg/dl (and ideally nonobese) be assigned to diet therapy. Obese women or those with fasting plasma glucose > 95 mg/dl on the OGTT should be referred to insulin therapy in order to minimize exposure of the fetus to a hyperglycemic environment.