Normal blood glucose levels are below 2 millimoles per liter and above 3 millimoles per liter for babies one to two hours and two to three days old, respectively, according to PubMed Central. Levels drop initially as the baby adjusts to life outside the womb.
Babies need energy such as glucose for healthy growth and development, explains PubMed Central. Though they are born with a store of glucose, it only lasts a few days. Breast milk is an excellent source of sugar, which converts to glucose in the body. Thus, it is essential that babies start breast-feeding within the first three days of birth.