Ninety-four infants of 28 weeks gestation or more were born to 85 women, 64 type I and 21 gestational diabetics, between 1969-1972 at Sabbatsberg's Hospital, Stockholm. Perinatal mortality rate was 6.3%. The follow-up study was conducted when the children were approximately 5 years of age and included a physical and a neurological evaluation, IQ determination of mother and child, and an interview of mother by a psychologist. Fifty-three infants of insulin-dependent (IDM) and 20 infants of gestational diabetic mothers (IGDM) (83%) participated, 3 families could not be traced and 12 were unwilling. The group lost to follow-up (13 IDM, 2 IGDM) had more perinatal complications including congenital malformations than the follow-up group. All children had normal physical and neurological development. IQ was normal, the majority were above 100, the average in IDM was 115 (range 98-144) and 112 in IGDM (range 95-133). No obvious relationship was found between maternal acetonuria during pregnancy, infant birthweight, blood glucose during first hours after birth or neonatal complications and IQ of the children. A correlation (r = 0.364, p less than 0.01) was found between maternal and child IQ. Mothers exhibiting emotional disorders (anxiety, depression) had significantly higher life stress scores based on 29 stress variables and reported more frequently about conduct and behavioural disorders in their children than mothers without emotional disturbances.