Gestational diabetes mellitus (GDM) is the most common metabolic disturbance during pregnancy. The prevalence is rising and correlates with the increase in maternal obesity over recent decades. The etiology of GDM is complex, with genetic and environmental factors implicated in mechanistic and epidemiological studies. GDM begets important short- and long-term health risks for the mother, developing fetus, and offspring. This includes the high likelihood of subsequent maternal type 2 diabetes (T2DM), and possible adverse cardiometabolic phenotypes in the offspring. The most clinically and cost-effective methods of screening for GDM remain uncertain. Whilst treatments with lifestyle and pharmacological interventions have demonstrated short-term benefits, the long-term impact for the offspring of intrauterine exposure to antidiabetic medication remains unclear. The prevalence of GDM is rapidly increasing and is set continue climbing in the context of the global obesity epidemic. GDM has serious adverse implications for the health of current and future generations through genetic and environmental mechanisms which remain incompletely understood. In addition, the disease poses a significant economic burden for healthcare systems, with variability in clinical practice often determined by resource limitations. The optimal timing of screening and diagnostic thresholds for GDM remain uncertain. Emerging evidence suggests intrauterine exposure to metformin may have an adverse impact on the offspring of women with GDM. There is an ongoing need for long-term follow-up of children exposed to metformin to clarify these potential associations and provide a more robust evidence base to inform clinical practice.