After you eat carbohydrates, glucose enters your bloodstream faster than your cells can immediately use or store it, so your blood sugar temporarily rises. How sharp that rise is depends on the balance between how quickly glucose enters your bloodstream and how efficiently insulin and your muscles help clear it. That is why the same meal can cause a relatively gentle rise in one situation and a much sharper spike in another. The good news is that many of those factors are things you can influence.

So when your blood sugar spikes after eating, there is rarely just one reason. What you ate, how much you ate, what you ate with it, what you do afterward, and how sensitive your cells are to insulin can all affect the size and duration of the spike.