# D/L and +/− labels of glucose

I had just started to read about carbohydrates when I came across D-(+)-glucose. My book says that the '+' sign refers to its optical rotation measured through the polarimeter, and that it could either be + or −, but throughout the book D-glucose is always designated with the + sign.

Is it possible for there to be D-(−)-glucose?

• – user7951 Jul 13 '17 at 18:18

• The naming along D (or L) is convention, based only about this peculiar $\ce{OH}$ group adjacent to the $\ce{CH2OH}$ in the Fischer projection. The rotatory effect however depends on the whole molecule. – Buttonwood Jul 13 '17 at 15:29