How much sugar can you eat before you go into a diabetic/sugar coma?

I don't have diabetes, but my mom always says if I eat too much junk I'm going to go into a sugar coma (e.g. skittles, a donut, milkshake, etc.) Can you go into a sugar/diabetic coma without having diabetes? How much sugar can you have before you go into a coma..if you can? please explain it in like food hahah if that makes sense like "a dozen donuts" or "a tub of cookie dough". thank you! :)