To reduce the risk for hypoglycemia, do not delay or skip your meal after taking the injection. Hypoglycemia can occur very quickly and usually within 2 hours after injection. Recheck blood glucose after 15 minutes to see if more carb is needed. After treating hypoglycemia due to Regular insulin, a snack is often needed to prevent another drop in glucose. Taking Humalog at bedtime or during the night is risky when not followed by food.
Severe hypoglycemia is more likely.