Abstract.Thirty‐five infants of strictly controlled diabetic mothers (IDM), 12 infants of gestational diabetic mothers (IGDM) and 29 control infants were studied to assess the influence of maternal blood glucose level during pregnancy on infant metabolic measurements. At 2 hours after birth the disapperance ratektof intravenously injected glucose was determined. Plasma concentration of glucose, insulin, FFA, glycerol and β‐hydroxybutyrate were followed in umbilical arterial blood. The 2 hour meanktvalue of IDMs (1.27) was higher (p<0.05) than in IGDMs (1.14) and controls (0.80), but the group mean values were no different at 3 to 5 days although thektvalues were higher. In 10 IDms,ktvalues were determined both at 2 hours (1.24) and at 3 days (1.39) without significant differences. Pretest FFA but not glycerol values correlated inversely toktvalues in IDMs and IGDMs. A late insulin peak at 60 min was found in both controls and IGDMs. Insulin responses were unrelated toktvalues. No relation was found between pregnancy glucose value (5 daily determinations during 4 and 2 weeks prior to delivery in DM and GDM respectively) or maternal glucose at delivery andktvalues of IDMs and IGDMs. According to the FFA and glycerol values at 2 hours after birth, 3 sub‐groups of IDMs and IGDMs were arbitrarily formed. IDMs and IGDMs of group 1 had glucose,kts, FFA, glycerol and β‐hydroxybutyrate values no different from controls, whereas sub‐groups 2 and 3 showed increasing metabolic deviations. Clinical data and pregnancy glucose levels could not separate the 3 sub‐groups. However, the day‐to‐day variation in maternal glucose was greater in sub‐group 3. Mean values of daily maternal blood glucose differences at 10 o'clock correlated to 2‐hourkts in IDMs. We conclude that strict metabolic control during pregnancy will normalize metabolic adjustment of the infant, thus supporting the maternal hyperglycemia‐fetal