William has had problems with asthma since before his diabetes diagnosis - the asthma showed up around 6 months old. Since you already have asthma I think I don't need to tell you what to look for in your child. I did notice with William that he would be very restless, unable to sleep well if at all, and taking many breaths per minute - I usually counted them. You can find the info on the web but depending on their age - something like 40 or more per minute for a really young kid would be too much.
After he got diabetes and when he'd get an asthma attack his bgl would go much higher for no other apparent reason except that. (that is before we started the meds) If they go on prednisone you will need to talk to your pedi endo as that literally tripled the dosage for insulin that William needed. Prednisone was a nightmare! I hope you don't have to go through that.
That being said I know zero about croup! When in doubt I've taken William to our HMO evening emergency care and they check his oxygen level.
As a completely side note - asthma and allergies often go together so I wanted to note to be careful with highly allergenic foods - especially peanut butter, shellfish, eggs, etc. I gave William some peanut butter on a cracker at 27 months (should have waited until he was 3) and he had a total anaphylactic reaction to it and is now touch allergic to peanut butter. I wish I had known the risks back then. Hopefully your child is wired differently!
mom to William, age 13, dx'd 3/04 and started pumping 10/04 - Animas 1200. Animas Ping started 01/09; T-Slim started 2/15; cgms Navigator start 4/6/09; RIP Navigator 9-1-11, Dexcom 7+start 10/11, G4 start 11/12.
and mom to Rod (17) not D