There are two separate things to think about where alcohol is concerned as well as the normal guidlines for people that do not have diabetes.
Some drinks contain sugar and the alcohol can give you low blood sugar.
Spirits do not contain sugar unless you have a mixer with it in which case you should concern yourself more with the mixer. Wine does have unfermented sugar in it and the sweeter the wine the more the sugar. The quantities in wine are not huge and most people can drink a couple of glasses without ill effect. Beer has sugar in it and the summer weight beers have even more and considering the amount of beer some people drink it is worth being a bit careful.
With respect to the alcohol, the liver provides sugar if your blood sugar is low but it won't do so while it is processing alcohol. Mayoclinic.com say that one symptom of a hangover is low blood sugar even in healthy people. You should be aware of this if you are injecting.
http://www.mayoclinic.com/health/hangov ... ION=causes