To be honest, I just completely ignore the 'not suitable for diabetics' warning on medicine. 99.9% of the time, the reason it's there is because it's not been tested on someone with diabetes so they're just playing it safe. Unless it clearly has a specific adverse interaction with any medication you're taking, it's probably fine.
You'll have high BGs when you're ill. You'll pretty much just have to put up with that but anything you can do to bring them back down to normal levels will shorten the duration of your cold and make you feel better. However, most cold treatment only deals with the symptoms - no-one has ever managed to find a proven way of reducing the duration of a cold.
My personal routine with a cold is to test every two hours, bolus as appropriate and dope myself up on all-in-one-tablets. I also take GABA. I used to originally take GABA as it was demonstrated to reverse T1 in mice, but as with all of these things, it's a different story when you're a person. But I found when I was regularly taking GABA, I just never got ill. Occasionally I'd feel a cold coming on but it would go within a few hours of taking more GABA. So now I've stopped taking it regularly but will hock back a few tablets when I'm ill - it seems to help me, anyway.
