Transient neonatal diabetes mellitus in sibs.

The occurrence of transient neonatal diabetes mellitus in successive male sibs is described. Both infants were small in relation to their periods of gestation and the placentas were abnormal. Subsequent investigation of the mother revealed a flat glucose tolerance curve with normal plasma insulin levels. Transient neonatal diabetes mellitus may be due to delayed matuiration of fetal δ-cells caused by a combination of maternal and placental factors.