Wow this is an old thread! but Alcohol stays in your system much longer than the sugar.
On a molocular level, they are pretty much the same. Alcohol: C2H6O and Sugar: C6H12 O6, With sugar being more complicated of course.
When you start drinking, Your body tries to get rid of them both as quickly as possible. Now the thyroid gland controls the rate at which the blood sugar is burned and the pancreas controls the blood sugar level by secretion of insulin or glucagon.
Most alcohol is broken down, or metabolised, by an enzyme in your liver cells known as alcohol dehydrogenase (ADH). ADH breaks down alcohol into acetaldehyde, and then another enzyme, aldehyde dehydrogenase (ALDH), rapidly breaks down acetaldehyde into acetate. The acetate is further metabolised, and eventually leaves your body as carbon dioxide and water.
Problem is your body likes handling and breaking down sugar as it is a natural substance known to it. So especially if you have low blood sugar, your liver will start to break that down fast and quickly and then store it for use later in the liver. Breaking sugar down requires water, and lots of it. So you end up drinking more because your thristy. But what about the Alcohol? Well it just gets passed back to the blood stream to be broken down later when your liver is happy with the sugar levels, so you get drunker and drunker. When you body finally does start to break down the Alcohol, it again needs water but at this time you have usually passed out or are sleeping. Since you have stopped drinking liquids, your body removes the water from itself in order to break it down, It gets this from your brain and from your muscles.
This is pretty much why you have a headache the next morning and feel like you have been put through a meat blender. This is why the drink water before you go to sleep and take a painkiller thing usually works the best, Because you have added water required for the process and the painkiller takes away the headache and sore muscles for a little while when you wake up.
Until we are able to get the liver to break down the alcohol first, we will always have hangovers, and is also why people who drink alcholol with water instead of soda's like coke, generally feel better in the morning than others as well.