The 50-g oGTT was applied to pregnant women suspected of having contracted diabetes. Carbohydrate tolerances were pathological in 23.6 per cent of all probands and in borderline vicinity in 17.9 per cent. The oral glucose tainting test thus worked according to expectation by revealing a relatiively high frequency of disorders of the carbohydrate tolerance. Yet, impaired insulin secretion was established rarely, with high response having been recorded from only seven per cent and delayed insulin secretion from 4.1 per cent. Low response was not found at all. No correlations were found to exist, by the 50-g oGTT, between disorders of the carbohydrate tolerance and insulin secretion. The groups involved differed but little with regard to their IRI mean value curves. Sugar excretion in urine was found to be increased with significance in response to pathological carbohydrate tolerance in early pregnancy and may be used as a complementary criterion for diagnosis.