Sixty pregnant "maturity-onset" (
insulin-independent), established and gestational, diabetics were treated with
Metformin in the second and third trimester after dietary treatment had failed. The incidence of
Metformin failure was 53.8% in the established diabetics and 28.6% in the "gestational" diabetics. The 27
Metformin failures were transferred to other
therapy, leaving for further analysis 33 patients who received
Metformin up till delivery. Two
neonatal deaths occurred in this group (1
congenital abnormality and 1 preterm infant) giving a perinatal mortality of 61/1000. This compares with a perinatal mortality of 103/1000 in the
Metformin failure group and 105/1000 in a group of
insulin-dependent diabetics treated during the same period. Apart from a high incidence of
neonatal jaundice requiring
phototherapy the infant morbidity in the
Metformin group was low. The mothers of 3 infants with
congenital abnormalities had received
Metformin only during the last trimester of their pregnancy.