Increased glucose use
Major causes of increased glucose use in a newborn include hyperthermia, polycythemia, sepsis, and growth hormone deficiency. Decreased gluconeogenesis
Two major issues that cause decreased gluconogeneis are inborn errors of metabolism and adrenal insufficiency. Depeleted glycogen stores
Most common causes of depleted glycogen stores are starvation and asphyxia-perinatal stress. Mechanism
There are many types of hypoglycemia, including transient and reoccurring. Each is associated with different risk factors and may have many underlying causes. Neonatal hypoglycemia occurs because an infants brain is dependent on a healthy supply of glucose. During the last trimester of pregnancy, glucose is stored in the liver, heart, and skeletal muscles. All newborns experience a physiological and transient fall in blood glucose, reaching a nadir at 2–3 hours of age before slowly rising over the next 24 hours. Newborns do have the ability to use an alternative form of energy, especially if breastfed. However, some newborns are only able to compensate this glucose deficiency up to a certain limit. Infants who have hyperinsulinism may increase the risk to develop hypoglycemia. There are other conditions that can increase the risk of an infant becoming hypoglycemic (See Risks). Diagnosis
Screening for hypoglycemia is done on every neonate on admission in the USA  but this is not recommended practice in all developed countries. One way of screening includes a heel stick to test the blood glucose level at the bedside. Diagnosing hypoglycemia in neonates requires two consecutive blood glucose readings of less than 40 mg/dL to properly diagnose hypoglycemia.
Bedside glucose monitoring is only effective if the equipment is accurate, rapid, and reliable. This form of testing is often faster and more cost effective. Laboratory serum glucose testing is the most accurate way of testing blood glucose levels. These specimens are either taken from the heel, arterial, or venous punctures and must be store immediately on ice in order to prevent glycolysis, further altering the results. USA guidelines recommended that the hypoglycemic neonate should have a glucose test every 2–4 hours for the first 24 hours of life. Guidelines in the UK, however, recommend pre-feed screening of at-risk infants at 2–4 hours of age (to avoid false positives when blood glucose is, ordinarily, at its lowest at 2–3 hours of age) and at the subsequent feed until a blood glucose level of  >2.0 mmol/L (36 mg/dL) on at least two consecutive occasions and is feeding well. 1. Medical history
Maternal diabetes mellitus, gestational hypertension, neonatal erythrocytosis, neonatal haemolysis of incompatible blood groups, perinatal asphyxia, severe infection, sclerosis, neonatal respiratory distress syndrome, etc., especially in premature babies, babies younger than gestational age and those who are underfed in the early stages of life are at risk of neonatal hypoglycaemia. 2. Clinical manifestations
Neonatal hypoglycemia should be considered if there are atypical clinical manifestations, if the symptoms improve after glucose infusion, or if there are neurological symptoms and signs that cannot be easily explained. 3. Blood glucose measurement
Postnatal glucose monitoring is the main method of early detection of neonatal hypoglycaemia.