| Unless you're a total idiot, alcohol is perfectly safe to drink if you have diabetes. I'm not sure of the interactions between alcohol and meds used to treat T2, but given what you hinted at your age I'm assuming you're a T1.
Here is my advice on drinking: Go for it.
Here is some more constructive advice: Go for it, but don't drink enough to make you pass out, and carry glucose tablets or something similar to prevent hypos. Also, try to eat something once you've finished drinking for the night. It's not absolutely essential to do so (I've managed to get away with it myself a few times), but it's the single best piece of advice I can give you, because eating something starchy will help soak up the booze and reduce your hangover, and will also help stop you going low whilst asleep.
Alcohol does make your bg drop, but to say this is somewhat misleading. Drinks such as lager or cider will in fact raise your bg for a while after consumption, and obviously alcopops and the like, which are basically just alcoholic sugar water, will definitely raise your bg. However, the effect of having alcohol in your system is that it keeps your liver occupied. This means your liver is far too busy filtering out the the alcohol to worry about releasing glycogen into your blood, which is why you will probably have a drop in bg levels a few hours after you've been drinking. My advice would be to go to bed having eaten something with slightly elevated sugars - you really don't want to have a hypo in your sleep when your liver's unable to do anything to help you.
As a practical tip for drinking on a night out, it can be helpful if the people you are drinking with know you're diabetic and that if you do pass out, they should take you to hospital and not just put you to bed. Another tip, which I've found very useful, is to vary your drinks. If you're drinking rum and diet coke, that's great because it's low in calories and won't jack up your blood sugar. However, every 3 drinks or so, have a rum and regular coke, or even just a regular coke. This will raise your bg levels a bit and compensate for drops in bg, and it doesn't mean you have to stop the fun.
Alcohol in itself can actually be a good treatment for diabetes - in fact elsewhere I've suggested that a small alcoholic drink before going to bed might help prevent the Dawn phenomenon. Basically though, the important thing to remember is that alcohol will lower your bg at a time when you are probably less able to deal with it, so make sure that you prepare beforehand. When you go to bed after drinking, assume that you are going to have a hypo at some point in a few hours, and therefore do whatever you would do to prevent a hypo normally.
And it goes without saying, check your bg when you can.  | 
