This is too complicated for you to deal with and potentially risky if you are not familiar with Type 1 diabetes and her specific care.
The problem is that some alcohol can cause high blood sugar initially (beer, carb containing coolers, etc.), but it can also cause low blood sugar as well. Usually this crash happens much later. Alcohol will also make her much more sensitive to her injected insulin, and she will probably need less to bring down a high. She may be at risk of severe low blood sugar if she has been drinking a lot and you have given her a "regular" correction dose.
DO NOT let her "sleep it off".This is how Type 1 diabetics have died. I don't mean to scare you, but this really *can* happen. But it doesn't have to. You are a good friend and you are right to be concerned. You need to call her parents, or at the very least, keep checking her blood sugar every hour to make sure she is in a safe range. Wake her up for a snack if needed. It is better to let her run a little high than low for tonight. Check to see if she has glucose gel on hand to rub in her cheeks if her blood sugar is low and you can't wake her up. If this is the case, and/or her blood sugar is extremely out of range, you need to call 911 ASAP. You need to be safe and not sorry. She may need to monitored in the ER overnight until she sobers up.
Note: Even if she has shown you how to use a GLUGAGON pen (used to help diabetics having a low blood sugar coma), this WILL NOT WORK if she has been drinking. She will need IV glucose. Call 911.
UPDATE: Please have her eat a snack RIGHT NOW, especially if she has dropped very fast. Make her something with carbs and protein, like a peanut butter sandwich. You can give her half of the sandwich if her blood sugar is still somewhat high. She might not need a full one, but as I said, it's better to be a bit high in this case to prevent a severe low. Test her again in an hour. If you can post her test results, that will help. There is a very good chance she could drop low. Watch for that and do not leave her. Once most of the fast acting insulin from her last injection has been used up (usually 4 hours) and/or she is in a good but a bit higher than normal range and had a snack, then she will proabably be ok.
If she is low, good treatments that go down easy are:
-Regular (NOT diet) pop
-Juice with sugar added
-Jam
-Cake frosting