Heart pounds & feel extremely tired after eating sugary foods. lying down helps. no other diabetes symptoms (such as more thirst). is this normal?

Hypoglycemia: Your symptoms might be due to low blood sugar, as counter-intuitive as that may seem. Some people's body over reacts to a high sugar meal and drives the blood sugar to low levels, causing such symptoms. Either way, whether you sugar is high or becomes low, the treatment is to avoid meals that are high in refined carbs and sugars!

Can't tell without: More information- like sugar number when gets symptoms- can check sugars with home glucose monitor bought in pharmacies.