Abstract Background In women without diabetes, little is known about the consequences of hyperglycemia during pregnancy for the offspring’s cardiovascular structure and function. Objective To investigate the association of maternal glycemia during pregnancy with cardiovascular risk markers in their children in GUSTO, a Singaporean birth cohort study. Methods Around 26 weeks’ gestation, a 75 g oral glucose tolerance test was performed and fasting plasma glucose (FPG) and 2-hour postprandial plasma glucose (PPPG) concentrations were measured. Gestational diabetes mellitus (GDM) was defined using WHO 1999 diagnostic criteria. At 6 years of age, we measured the child’s carotid intima-media thickness (cIMT), carotid-femoral pulse wave velocity (cfPWV), aortic augmentation index (AIx), and blood pressure (BP). Association of maternal glycemia during pregnancy with cardiovascular risk markers in their children were analyzed using multiple linear and logistic regressions. Results Analysis were performed on 479 mother–child dyads. Higher maternal FPG was associated with higher cIMT and, in males, with a higher cfPWV in the offspring (adjusted β [CI 95%], cIMT: 0.08 per 10mm increase [0.02; 0.15], cfPWV: 0.36 m/s [0.01; 0.70]). Higher 2-hour PPPG was associated with higher cfPWV and AIx. Gestational diabetes mellitus was associated with higher AIx. No association was found between maternal glycemia and their offspring blood pressure. Conclusions among mothers without pre-existing diabetes, higher glycemia during pregnancy was associated with mild structural and functional vascular changes in their children at 6 years of age across a continuum. These results support the necessity to monitor maternal glycemia during pregnancy even in the absence of pre-existing diabetes or diagnosed GDM.