A prospective cohort study of women with a history of gestational diabetes mellitus (GDM) revealed that participants who increased their physical activity from baseline levels over 16 years of observation had a 47% reduced risk of developing type 2 diabetes mellitus (T2DM), when compared with those who maintained their total levels of physical activity (RR 0.53, 95% CI 0.38–0.75). Among 4,554 women with GDM, 635 cases of T2DM were identified over the course of the study (1991–2007).