Control of the blood sugar level in the neonatal period

Abstract

The present knowledge of carbohydrate control, of the neonatal adrenal, and of hypoglycaemia in the newborn is briefly reviewed, and an attempt made to link the latter with the anatomical and functional changes in the adrenal gland at this age. Evidence in favour of such a linkage would have been obtained had it been possible to show that simultaneous movement of blood sugar levels and eosinophil counts in normal newborn infants occurred in opposite directions. Serial studies of blood sugar levels and eosinophil counts were carried out in a group of 32 normal infants. Previous work on the neonatal blood sugar levels is open to some criticism but it was confirmed that the variation between individuals at any time unit was wide and also that considerable variation occurred in individual infants at each time interval. This scatter of individual values at any time unit was so great as to render the arithmetic mean of the group valueless as representing the behaviour of individuals. The blood sugar level tended to fall fairly rapidly in the first hours after birth but was stabilized by about four hours. It remained as an impression that those individuals in whom the blood sugar rose immediately after birth were those who approached more closely to the two minutes accepted as the upper limit of normal before respiration was established. An upward trend in blood sugar values over the 10-day period occurred in the majority. From scatter diagrams, not reproduced here, there was no correlation between body weight and the blood sugar level. The eosinophil levels of the group were appreciably higher than in adults. The scatter of eosinophil counts between individuals was great at any time unit and also in the same individual at any time interval. As with blood sugar this scatter was sufficiently great to invalidate the group mean as a representation of individual behaviour. Twenty-six of the infants showed a fall in eosinophils, many of them a substantial fall, in the first few hours. The relationship between the blood sugar level and eosinophil count was studied in individual cases and five distinct patterns found. These showed that the pattern of inverse movement of the means of the two features was false. The mean blood sugar level rose steadily from the third to the tenth day whereas the fall in the mean eosinophil level took place largely between the third and fourth day. Comparison of the change in mean values was therefore impossible over the same time interval. When the behaviour of individuals was studied it was clear that simultaneous movement of blood sugar values and eosinophil counts in opposite directions did not take place but it remains possible that direct measurement of the sugar-fat-nitrogen hormone production would show a relationship between a period of adrenocortical hypofunction and hypoglycaemia.