Cinnamon can lower blood sugar quickly. Cinnamon lowers blood sugar immediately after use and can stabilize blood sugar for 12 hours. You should not take more than 6g of cinnamon per day. If you are taking insulin you should also not take cinnamon. Some other foods also help you lower blood sugar quickly, but not immediately. They only take effect a few hours after you eat or drink them. Here are some of the best foods to help lower blood sugar quickly: -Spinach. -Peanuts and peanut butter. -Pineapple. -Broccoli. -Oysters. -Oat. -Pumpkin seeds. -Okra.