Make sure you adjust your basal rates to keep your sugars down (4.5-6.5mmol/L range) as much as possible. If you spend your days with sugars outside of the normal range your body won't do a very good job fighting off the cold and a 4 days cold could turn into a 7 day cold very easily all because of high sugars.
Other then making sure you get your levels down as close to normal as possible, just treat it like you normal would - take some advil, or whatever medicine you normal do (just try to avoid sugary stuff, or anything that may put your to sleep - you may confuse that 'out of it' feeling with low blood sugars), sleep lots, eat well, and drink lots of liquids and focus on getting better!
The worst part of diabetic colds is the high BS can prolong them.