My wife is type one. Our basset hound gets nervous and stays by her side when she’s high or low. He’s never had any training but he works better than her dexcom continuous monitor.
I have a chocolate lab, but all she does is retrieve the morning paper from the end of the driveway.
I got my 2 poodles from a breeder who is type 1 diabetic. She raises her dogs for temperament to be potential service dogs. All her dogs alert for her blood sugar levels. If they could only cross a poodle with a German Shepherd to produce a smart, obedient dog that doesn’t shed. You can practically see the wheels turning in the poodle’s heads deciding if it’s worth it to them to obey, whereas my Shepherd just does but sheds a couple dog’s worth of hair a year. In a perfect world....