I was having heart palpitations accompanied by labored breathing all evening, was beginning to think I needed to go to the doctor. About 3 hours after eating, I tested my blood sugar and found out the likely cause; my glucose tested 272, the highest ever. The only explanation is I didn't inject any insulin before eating dinner. Since injecting a correction insulin dose, the palpitations are gone, and I feel more relaxed. I must have injected air instead of insulin, caused by filling the syringe with air with the intent of injecting the air into the vial of insulin but got distracted and failed to draw up the insulin.
I will have to be more careful filling the insulin syringe, and I hate to admit it, I might need help doing this.