My 7 year old son has had diabetes for 2 years. He has had 2 episodes of tachycardia (heart rate today was 230) which self resolved. His blood sugar was 45. The ER doctor and his pediatrician think it may be due to low blood sugar, or rapidly falling sugar. Is this common? What follow up testing do you recommend? He has had 2 regular 12 lead EKG’s with no abnormalities found, although we haven’t “caught” the SVT [superventricular tachycardia] on tape yet.

I assume that the heart rate of 230 was measured with some kind of cardiac monitor and not measured by palpating the pulse or listening with a stethoscope to count the heart rate (it would be almost impossible to measure this fast a heart rate accurately without using a monitor). Although low blood sugar can cause a fast heart rate, a rate of 230 is higher than I would expect and I would be concerned about an arrhythmia (abnormal heart rhythm.) You would have to get an EKG while your child is symptomatic to see what is going on. Perhaps you could arrange to rent an “event monitor” for a few weeks. This is a recording device that can be put under the arm when the child is symptomatic and can send the recording over the phone. If you are unable to catch a fast heart rate spontaneously, you might want to consider letting your child develop a low blood sugar on purpose in the doctor’s office with a monitor on to see if you induce a fast heart rate.

TGL