Bread worse than cake?

A lot will depend on portion size - did you calculate the g of carbs in each item?
But other factors will be the carb, fat and protein content of the rest of the meal, because they affect the speed of digestion.
There is no guarantee that your 2hr prick tests caught the bg peak of either meal.
Hope that helps.

And for some yes grains are worse than old fashioned sugar.

A couple of thoughts:

1) It could be that the second "cheat" had more impact because it was the second one, and it would not have mattered which one of those items was eaten secondly. In other words, some residual effects from the cake, plus the bread lead to a bigger spike than the cake.

2) Sugar as it turns out is an interesting one. The fructose portion doesn't always become glucose in your blood, but instead turns into fat in your liver. This can appear gentler if you only look at the meter, but it's the fatty-liver that's mostly behind the insulin resistance in the first place, so in a way, the meter lies.

for me, it depends on the flour used, and the presence of sugar.

Home made stone ground organic flour bread works best for me.

I can eat bread, usually 10 - 13g carbs per slice, small bagels and Pizza with little effect on my BS but tortillas will raise my BS up to 10.00 which is high for me; although after 3 hours it’s usually back down to between 7& 8 and not back to normal until 4 hours later.

Sucrose is only 50% glucose. Grains are worse in that regard. The unseen impact of sucrose is its 50% fructose component that directly impacts the liver and increases insulin resistance.