My understanding is that alcohol is metabolized into sugar. Alcohol of any kind makes your blood sugar go up.
Not really.
Alcohol is converted to acetaldehyde by your liver. It'll then combine with pyruvic acid to produce acetate. The final stage converts acetate and a free water molecule to lactic acid (vinegar) and CO2.
If you drink faster than your liver can handle it, some of the acetaldehyde is released into the blood (the getting drunk part) along with the acetates ("alcohol on your breath"). It's possible that an acetate in the blood can combine with oxygen to make a molecule called oxaloacetate, which, in turn, could be converted to glucose; but that'd be a very small percentage of total amount consumed. If it happens at all.
The important part is in the second stage (acetaldehyde -> acetate), the pyruvic acid is normally used to convert glucose. Since acetaldehyde is a toxin, the liver will use the available pyruvic acid to break down the acetaldehyde first, preventing any further metabolism of glucose.
So if you are already digesting a meal, blood sugar will rise because of buildup of unconverted glucose. On the other hand, if you haven't eaten your blood sugar will drop as your brain uses up the available glucose (the brain has a different glucose metabolism than the rest of the body).