Does falling blood glucose feel like hypoglycemia?

Sometimes. Symptoms of hypoglycemia are divided into the adrenergic and the
neuroglycopenic.  Adrenergic responses are caused by increased activity of
the autonomic nervous system and may be triggered by a rapid fall in blood
glucose (bG) or by low absolute bG levels; symptoms include

  weakness
  sweating
  tachycardia
  palpitations
  tremor
  nervousness
  irritability (sound familiar?)
  tingling of mouth and fingers
  hunger
  nausea or vomiting (unusual)

The autonomic nervous system activity also causes the secretion of epinephrine,
glucagon, cortisol and growth hormone.  The first two are secreted rapidly and
eliminated rapidly.  The second two are secreted slowly and remain active for
4-6 hours, and may cause reactive hyperglycemia.

Neuroglycopenic responses are caused by decreased activity of the central
nervous system and are triggered only by low absolute bG levels; symptoms
include

  headache
  hypothermia
  visual disturbances
  mental dullness
  confusion
  amnesia
  seizures
  coma

The above information is from Mayer Davidson's _Diabetes Mellitus: Diagnosis
and Treatment_.

Remember, as always, that individual responses vary greatly. The exact set of
symptoms encountered will vary. It's not impossible that some of the symptoms
will fall in the other category for some individuals.