How long does it take for an insulin overdose to take effect if I have hyperemesis?

That depends. How an overdose of Insulin will effect you depends on many factors. Short-acting Insulin starts to work in 15 minutes. Long-acting varieties like Lantus or Levemir (insulin detemir) take hours. You have to take your glucose level into account as well. If you blood sugar is at 250 it will take a lot longer for you to feel the effects of too much Insulin than if it is 110. Insulin sensitivity is the third variable.