Hello,
It depends a lot on what insulin you are using.
Regarding changing the time of the shot, some insulins are more 'forgiving' than others.
The recommended insulins here are the longer-lasting insulins; Lantus, Levemir, Prozinc and PZI. Although some folks have had success with other insulins.
Folks here recommend that the depot insulins, Lantus and Levemir, are given as close to 12 hours apart as possible.
Prozinc and PZI are more flexible with regard to variable shot times.
Which insulin is your cat on?
Eliz