I asked the same question to one of the pump manufacturers a couple of years ago.
At the time, it was explained that there is limited interest from phone manufacturers as they do not want to be held responsible for missing or incorrect requests being made from the phone to the pump.
If the pump gave too much or too little insulin due to the request from a phone being corrupted, Apple, Samsung, etc, could be deemed responsible for the death of a pump user.
There may be unofficial apps coming out to control pumps but I think we are some way from Apple willing to be able to prove they are 100% accurate.