Neonatal hypoglycaemia can be a stand-alone condition or a clinical manifestation of other conditions. Signs and symptoms
The way in which neonatal hypoglycemia symptoms may be presented is vague or hard to tell apart from other conditions. The symptoms can be confused with:

hypocalcemia
Sepsis
CNS disorders
Cardiorespiratory problemsNeonatal hypoglycemia can also show no symptoms in some newborns or may be life-threatening.Some observed symptoms are (these symptoms may be transient but reoccurring):

Jitteriness
hypothermia 
irritability 
pallor 
tremors
twitching
weak or high pitched cry
lethargy
hypotonia
generalized seizures
coma
cyanosis
apnea
rapid and irregular respirations
diaphoresis
eye rolling
refusal to feed
hunger

Causes
Risk Factors
Mother
Risk factors in the mother that increased the risk of developing hypoglycemia shortly after birth include:

Type 1 diabetes
Gestational diabetes mellitus (Transient)
Intrapartum glucose administration (Transient)
Gestational hypertension
Preeclampsia
Terbutaline administration (Transient)
Intrauterine growth restriction (Transient)
Perinatal stress or asphyxia (Transient)

Baby
Babies which have an increased risk of developing hypoglycemia shortly after birth are:

hypothermia (Transient)
polycythemia (Transient)
hyperinsulinism (Recurrent)
IEMs (Recurrent)
Beckwith-Wiedmann syndrome (Recurrent)
nesidioblastosis (Recurrent)
Rh isoimmunization (Recurrent)
Certain endocrine disorders (Recurrent)
fetal hydrops
Prematurity (Transient)
congenital malformations
small for gestational age (Transient)
Large for gestational age (Transient)

Hyperinsulinism
The most common cause on neonatal hypoglycemia is hyperinsulinism. Hyperinsulinism is also called persistent hyperinsulemic hypoglycemia of infancy (PHHI). This is seen very frequently to the neonates born from mothers with diabetes. Congenital hyperinsulinism is correlated with the abnormality of beta-cell regulation within the pancreas. Isolated islet adenoma, which is a focal disease, is often the cause of congenital hyperinsulism. Drug-induced hyperinsulisim is correlated with the administration insulin or use of hypoglycemic medication. In critical cases, a drug called Diazoxide is availed to stop any secretion of insulin. Limited glycogen stores
Limited glycogen storage occurs in premature newborns or newborns that had intrauterine growth retardation.
Long term complications of neonatal hypoglycemia may include:

Neurologic damage that results in mental retardation
Developmental delay
Personality disorders
Recurrent seizure activity
Impaired cardiovascular function

Research
Continuous glucose monitoring devices have been suggested to be helpful for improving blood glucose monitoring in neonatal infants, however, the devices have not been approved for use in this age group and the potential benefits and risks are not clear from available studies.The taḥnīk also exercises the muscles of the mouth and helps with the circulation of blood in the mouth - this may help the baby to be able to suck and take mothers milk. It is also credited to prevent neonatal hypoglycemia in newborn babies. See also
Congenital hyperinsulinism
Hyperinsulinemic hypoglycemia

References
Bibliography
Walker, Marsha (2011). Breastfeeding management for the clinician : using the evidence. Sudbury, Mass: Jones and Bartlett Publishers. ISBN 9780763766511.