They call it G.I or Glycemic Index.
In lay person's terms
gylcemic = sugar rush
A GI of 100 means it is equivalent to common sugar.
Some foods eg lentils, green beans have low GIs ie less than 35.
Some foods have GIs of about 50 eg sweet potato, rye,
Some foods have high GIs of 80 or above eg potato, white bread.
IMHO it is worth finding out about GI and using it as one factor in choosing a diet for a healthier life. There are plenty of books in most bookstores that will give detailed information.