During pregnancy glucose tolerance in the mother is affected. Glucose tolerance in pregnancy, as in the non-pregnant state is a continuum, represented by a distribution curve shifted to the right, with no clear divide between normal and abnormal. Many of the problems associated with overt diabetic pregnancies can be seen in infants of GDM pregnancies, such as macrosomia, neural tube defects, neonatal hypocalcemia, birth trauma and subsequent childhood and adolescent obesity. Impaired glucose intolerance (IGT) in pregnancy is also a major risk factor for the development of NIDDM (non-insulin dependent diabetes mellitus) and IGT in later life and is associated with not only an increased risk for coronary heart disease (CHD) disease but also many other morbidities and mortalities associated with overt diabetes. The problem remaining to be resolved is the precise level of glucose intolerance in pregnancy that poses a significant risk for the later health of the mother. Nor is increased gestational glucose intolerance the only reproductive event that has been linked with future NIDDM risk. Other factors have been known to predispose pregnant women to the risk of future diabetes (e.g. BMI, age and weight change). The findings of the present study suggest that the association of glucose intolerance during pregnancy, with the subsequent incidence of diabetes and certain co-morbidities in the mother, is continuous throughout the range of glucose concentrations studied. The risk of future diabetes is also affected by certain maternal characteristics (BMI at index pregnancy and at follow-up, weight change).