Hey...even we humans have differing colours. A lighter colour stool can also just mean that it passed more quickly than usual and didn't get time to turn a darker brown. Or it could be just a difference in batches of food. Even though on the same food, sometimes the formulation is a bit different.
Without any other signs....I wouldn't get worked up over it. I'm sure that before the diabetes dx, you wouldn't have noticed the change of colour.
Relax a bit and just wait and see but, as long as there's no other symptoms happening, just a watchful eye. Of course, if it's driving you nuts with worry, a call to your vet after another movement (IF it's not to your liking) might put your mind at ease. I don't think it's going to be necessary though, given what you've said so, try to just relax.