Insulin secretion and glucose metabolism were studied during intravenous and oral glucose tolerance tests performed in one day and seven day old full-term and premature infants. Mean glucose disposal during the intravenous tests was more rapid in seven day old than in one day old infants.Insulin responses after intravenous glucose were characterized by higher insulin levels during the initial phase and lower levels during the second phase in both seven day old premature and full-term groups as compared with the patterns seen in one day < old infants. No differences in the mean values for blood glucose and plasma insulin were found among the four groups of infants at any time during the oral tests. DIABETES 23: 172-78, March, 1974. The low disposal rate of glucose administered intravenously in the newborn infant has been correlated with a reduced and delayed rate of insulin secretion. 1 " 6 However, it has been noticed that after the third day of life, the glucose assimilation coefficient (K t ) increases. 7 " 10 Since an increase in the pancreatic content and release of insulin in vivo (and in vitro in animals) has been observed in the immediate postnatal period, 1 1 ' 1 4 comparisons were made between insulin secretion in one day and seven day old full-term and premature infants. MATERIAL AND METHODSSubjects were 127 newborn infants: 36 one day old and 32 seven day old full-term infants and 27 one day old and 32 seven day old premature infants. Infants who were studied at one day of age were not restudied on the seventh day after birth, but groups of different infants were used. The mean birth weight of the fullterm infants was 3.41 kg. (range 2.96 to 4.05 kg.), and gestational age ranged from thirty-eight to forty weeks. The premature infants had a mean birth weight of 2.02 kg. (range 1.79 to 2.52 kg.), and their gestational age ranged from thirty-one to thirty-six weeks. The mean body weights were similar in the groups of premature infants. The tests were performed on the first day of life before any oral or intravenous feedings were started and, on the seventh day, on infants who had fasted for six hours. Infants of diabetic mothers, infants with hemolytic disease or other serious disorders and infants small for gestational age were not included in this study.Glucose tolerance was assessed with both intravenous and oral glucose tests. Intravenous glucose tolerance tests (IVGTT) were performed by rapid injection of glucose (1 gm./l kg. body weight/30 sec). The IVGTT was performed in 26 one day old full-term infants, 22 seven day old full-term infants, 15 one day old premature infants and 20 seven day old premature infants. Specimens of blood were taken at 0, 1, 3, 5, 10, 20, 30, 40, 60 and 90 minutes during the test for glucose and insulin determinations. Oral glucose tolerance tests (OGTT) were performed by administration of glucose in a dose of 2. 5 gm./l kg. body weight using a 40 per cent solution via nasogastric tube. The OGTT was performed in 10 one day old full-term infants, 10 seven day old full-te...
Twenty-two erythroblastotic infants (IEF), 22 normal infants, and 12 infants of diabetic mothers (IDM) were studied during their first day of life. Blood glucose, plasma insulin, and growth hormone were measured in the first 90 minutes after I-V glucose injection (1 gm/kg). Mean fasting blood glucose of normal infants was significantly higher than that of IDMs. In four IEF, blood glucose levels lower than 20 mg/100 ml were observed. No significant difference of glucose tolerance (Kt) was found among the three groups of babies. The mean fasting plasma insulin level in IDMs was significantly higher than in control infants and in IEF. In the IEF a significant correlation was found (A) between hemoglobin (Hb) and Kt values, (B) between Hb and fasting plasma insulin. (C) between fasting blood glucose and fasting plasma insulin, and (D) between Kt and the sum of plasma insulin levels 3, 5, and 10 minutes after I-V glucose. All normal babies and sixteen IEF showed a double course of insulin response. IDM showed a nearly monophasic pattern, but with a secondary minor peak between 30 and 60 minutes in some. In six (four with hypoglycemia) of the IEF group a single peak response of plasma insulin was found, together with mean Kt and fasting plasma insulin values higher than those of control infants. Fasting mean HGH concentration in plasma showed no significant difference among the groups of infants. During intravenous glucose tolerance tests mean values in IDM significantly higher than in normal infants and in IEF were found at 90 minutes.
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