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Effects of oral glucose and protein load on plasma glucagon and insulin concentrations in small for gestational age
Insights
Small for gestational age (SGA) and appropriate for gestational age (AGA) newborns show similar pancreatic hormone secretion in early life. This study compared glucose, insulin, and glucagon levels in both groups after a nutrient load.
Area of Science:
- Neonatal endocrinology
- Pediatric metabolism
- Perinatal physiology
Background:
- Infants small for gestational age (SGA) may exhibit altered metabolic responses.
- Understanding glucose, insulin, and glucagon dynamics is crucial for neonatal care.
- Limited data exists on the hormonal responses of SGA infants to nutrient loads in the first 48 hours of life.
Purpose of the Study:
- To compare portal and peripheral blood glucose, insulin, and glucagon levels in SGA and appropriate for gestational age (AGA) newborns.
- To investigate the hormonal responses of these infants to an oral glucose and protein load within the first 48 hours of life.
Main Methods:
- Measurement of blood glucose, plasma insulin, and plasma glucagon in portal and peripheral circulation.
- Administration of an oral glucose and protein load (1 g/kg each) after a 4-hour fast.
- Comparison of hormonal levels between SGA and AGA infants during the first 48 hours of life.
Main Results:
- Fasting blood glucose was higher in the portal vein than the aorta in both SGA and AGA infants.
- Both groups showed a significant rise in blood glucose after the nutrient load.
- Insulin response to the load was minimal in SGA infants compared to AGA infants, with significant increases only observed in the portal vein of SGA infants.
- Glucagon levels did not significantly rise in SGA infants after the load, unlike in AGA infants.
- The insulin-to-glucagon molar ratio increased significantly in the portal vein of both groups after the load.
- No significant differences in mean blood glucose, insulin, or glucagon levels were found between SGA and AGA infants when directly compared.
Conclusions:
- SGA and AGA premature infants exhibit similar patterns of pancreatic hormone secretion in the initial days of life.
- Despite some differences in response magnitude, the overall secretory capacity for insulin and glucagon appears comparable between SGA and AGA newborns.
- These findings suggest that the endocrine pancreas functions similarly in both SGA and AGA infants during the early neonatal period.
Abstract:
This paper reports portal and peripheral blood glucose, insulin, and glucagon levels in small for gestational age (SGA) and appropriate for gestational age (AGA) newborns during the first 48 hr of life. These parameters were studied after an oral glucose and protein load (1 g/kg of each) after a 4-hr fast. In AGA and SGA infants, mean fasting blood glucose level was significantly higher in the portal vein than in the aorta (P less than 0.05). After the load, mean blood glucose level rose significantly in both vessels. The mean fasting plasma insulin level was low and was similar in both vessels. After the load in the AGA group mean plasma insulin level rose significantly at 45 min both vessels (P less than 0.05) (52.1 +/- 37.2 muU/ml in aorta and 91.8 +/- 75.3 muU/ml in portal vein). In the SGA group, the insulin response was minimal in the aorta and in the portal vein; the increase was significant only in the portal vein (P less than 0.05) at 180 min (47.1 +/- 25.3 muU/ml). The mean fasting plasma glucagon level was higher in the portal vein than in the aorta in both groups (P less than 0.05). After the load in AGA infants plasma glucagon rose significantly from 193 +/- 55 pg/ml at zero time to 290 +/- 76.8 pg/ml at 180 min (P less than 0.01) in the aorta but not in the portal vein. In the SGA group, the mean plasma glucagon did not rise significantly in the aorta or in the portal vein (from 231.2 +/- 54.3 pg/ml at zero time to 293.7 +/- 123.5 pg/ml at 180 min in the portal vein). The molar ratio of insulin to glucagon (I/G) rose significantly after the load in the portal vein in both groups of infants (AGA 2.48 +/- 2.06 at zero time to 5.08 +/- 4.06 at 180 min; SGA infants from 2.2 +/- 1.98 at zero time to 4.16 +/- 2.59 at 180 min). When both groups of infants were compared there was no significant difference either in the aorta or in the portal vein in mean blood glucose, mean plasma level, and plasma glucagon level. It is concluded that SGA and AGA premature infants are similar in regard to secretion of both pancreatic hormones in the first days of life.