Reduction reaction
Aldoses and ketoses are reduced to the corresponding polyhydroxy alcohols by sodium borohydride, sodium amalgam, etc. So, in this reaction, glucose is reduced to glucitol (sorbitol).
Polyhydric alcohols are also called sugar alcohols and are the hydrogenated forms of the aldoses or ketoses. Glucitol, also known as sorbitol, has the same linear structure as the chain form of glucose, but the aldehyde (-CHO) group is replaced with a -CH20H group (at C-1).