Patch
The reason why drinks such a wine, spirits lower the BG is to do with the liver, because the liver can not muliti task, so why it is processing the alcohol it can not produce or store any gluegon in your liver, this stops any glucose going into the blood stream from the liver hence the drop in BG... For T1 this increases the dangers of having a hypo..
As to weather to drink red wine before your hospital appointment, well if you do there is a good chance that they might suggest that you pay a visit to a AA meeting!