Interestingly seeing, or smelling foods can cause insulin release[0]. Perhaps it's not surprising that tasting foods would.

But it does make me wonder. If evolution was so concerned about blood sugar control it led to insulin release even before you ate (and that in evolutionary terms foods were very low in sugar and simple carbs). What must a doughnut do to our physiology?

[0] https://www.sciencedirect.com/science/article/abs/pii/002604...