This discomfort can be caused by an excess of sugar in the blood (hyperglycemia), by "heartburn" (the rise of stomach acid into the esophagus), or both.
The first thing to do is drink plain water. This will give your kidneys the necessary fluid to flush out the excess sugar and help restore your blood sugar level to a healthy state.
If you are experiencing the "burning chest" feelings of heartburn, do not lie down. Instead sit down and take an antacid, again with plenty of water. (Antacids can cause constipation on occasion, so plenty of water is essential).
Also mild exercise can be quite helpful - eg. go for a walk. Vigorous exercise is not recommended when feeling stomach pain or distress.
If your symptoms persist for more than a few hours, consult a doctor immediately.