Answer:
  Mr. Kenji Nakamura who specializes in medical emergency procedures kindly answered the above question.
 
 
Why do we use I.V. for treating acute alcohol intoxication?
  Alcohol (Ethanol) is metabolized in the liver and changed into acetaldehyde and then into acetic acid. When alcohol is metabolized, it consumes water resulting in dehydration.

  Therefore, intravenous injection is excellent for treating dehydration. This is the main reason why people start feeling better after having received I.V. at emergency hospitals.

  In addition to hydration, another benefit of administering I.V. to acute alcohol intoxication patients is that I.V. solutions lower the alcohol content in the blood. Regarding your question, I don’t think that the glucose in the I.V. solution has anything to do with alcohol metabolism. In fact, the I.V. solution we commonly use at our hospital for the treatment of acute alcohol intoxication is called "Lactec Sollant Soldem" (commercial name) which closely resembles our own body fluids. We never use I.V. solution with glucose for this purpose. I must say that the procedure I am referring to here is used at the first aid stage, and I am not very familiar with the procedures the doctors use thereafter.
 
Symptoms of acute alcohol intoxication
  The following are the major symptoms of acute alcohol intoxication:

• Central nervous system
  loss of consciousness, spasm or convulsion, coma

• Respiratory system
  insufficiency or suppression of breathing

• Circulatory system
  cyanosis, hypotension, palpitation, shock

• Digestive system
  nausea, vomiting 

• Others
  incontinence, hypothermia, etc.

The first aid treatments for the major symptoms are as follows: 

• loss of consciousness
  restoration of respiratory tract

• hypothermia
  retention of body heat

   Some people die from inhaling foreign objects; numbers of people die of hypothermia when they are heavily drunk and fall asleep on the street. Therefore, we need to be especially cautious during the winter season.
  
   
Acknowledgement
  We would like to thank Mr. Kenji Nakamura for his careful teaching and kind support for this answer.