Generally the advice is don't bolus for alcohol. Spirit with diet mixer shouldn't raise levels. Take it slow drinking something you aren't used to, try to alternate a whiskey with a water. Make sure the friends you are with know you are diabetic and know what to do if you hypo. Make sure to test before bed and have a carb snack to go to bed with. When your liver is busy processing alcohol it won't do a glucose supply overnight like it normally does - so you might drop low in the early hours of the morning. Treating a hypo when you are hungover could be rather a challenge.