A standardised breakfast tolerance test in pregnancy: comparison with the 75 g oral glucose tolerance test in unselected mothers and in those with impaired glucose tolerance.

There is still disagreement concerning the optimal procedure for the diagnosis of milder degrees of hyperglycaemia in pregnancy. We have compared the results of a 75 g oral glucose tolerance test (OGTT) and a standardised breakfast test performed one week apart in 102 non-diabetic women with a singleton pregnancy. There was poor correlation between the two tests (r = 0.15) at two hours, and neither test was predictive of adverse maternal or fetal outcome. One hundred and four patients with impaired glucose tolerance, diagnosed at 30 weeks' gestation by 75 g OGTT, subsequently had a breakfast and lunch meal profile. There was no significant correlation between the two-hour OGTT value and either the two hour post-breakfast value (r = 0.35) or the maximum profile value (r = 0.33). Using the WHO diagnostic criterion of > 8 mmol/l for the OGTT and a maximum glucose concentration > 6.8 mmol/l for the meal profile, there was no relationship between an abnormal result in either test and pregnancy outcome. In our obstetric environment, the 75 g OGTT, a standardised breakfast test, and a structured meal profile, all failed to provide a useful indication of pregnancy outcome in mothers not already known to have diabetes.