Probably depends on your white bread. My understanding is that any glycemic delta in white bread is primarily a function of the fiber. White bread without fiber is, to a first approximation, sugar.
A lot of white bread has actual sugar or high-fructose corn syrup in it as an ingredient. How much of that is to start the yeast and how much is for taste varies by brand.
Whole-grain/white can be misleading as far a sugar goes. I've had whole-grain brands that were so sweet that I couldn't stand to use them for sandwiches.
I believe I read a "study" recently where a news headline analysis found that roughly a third of question-headlines were "yes", the other two thirds? "No" and "Maybe"
Turns out Betteridge's law is just something snarky Internet people say.
For further reference (as it seems I've been downvoted possibly for my own snark on this one) - since I can no longer edit the original comment, here are some references
Additionally there was a publication in a statistical journal which also discussed the "phenomenon" http://link.springer.com/article/10.1007/s11192-016-2030-2 which also found that it wasn't a factual assertion (in academic papers).
Anyways - if the downvote was for something other than my own snark I'd love to hear what it was.