We have a yorky that gets insulin shots twice a day. Eating regular consistent size meals along with the scheduled shots is important.
Out cat was recently diagnosed with diabetes too. We give him 2 doses a day, shots in the belly, he does not even feel it. We use Lantus insulin in a pen, it's much much easier than vials and syringe. Dial in the number of units and just do it. Biggest issue for us is to always be home at 7am and 7pm for feeding and insulin, it's important to keep the timing consistant.