Glucose metabolism in a term infant with transient hyperinsulinism and high carbohydrate intake

Transient hyperinsulinaemia is a well-known cause of hypoglycaemia in newborn infants. The hypoglycaemia may be caused by a decreased glucose production and/or an increased glucose uptake. Whether the increased uptake is caused by increased glucose oxidation or increased non-oxidative disposal is not known. The aim of this study was to investigate the fate of the large amount of glucose infused in a term infant who developed hypoglycaemia due to transient hyperinsulinaemia shortly after birth and was treated with high glucose infusions. On day 6 an indirect calorimetry study was performed, together with a glucose turnover study. Carbohydrate intake was 13.6 mg/kg per minute (19.6 g/kg per day). Both studies were repeated on day 11, when carbohydrate intake was normalised to 7.8 mg/kg per minute (11.2 g/kg per day). Glucose oxidation was 28% higher and non-oxidative glucose disposal was 257% higher on day 6 as compared to day 11. Our results indicate that hypoglycaemia during hyperinsulinism is the result of increased non-oxidative disposal of glucose and not increased glucose oxidation. The results indicate a remarkable capacity of the newborn for lipogenesis during high carbohydrate intake.