I recently became friends with a high school teacher from Texas. He wrote to me earlier in the week regarding my WWII jukebox, and he is working our site into his lesson plans. 
What an honor.
This afternoon he sent me a question and I am placing the question and answer here. GREAT question! 
Hi Marion,
I hope I'm not bothering you but I just tried to find an answer to something on the internet to no avail and thought you might know off the top of your head. I know that sugar was rationed in WWII but why?
Someone told me that it is because they used sugar in explosives but I haven't been able to confirm that. Do you know if that is true?
Thanks,
Ferryn Martin
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Hi Ferryn:
Happy to answer. Actually it was due to import shortages and the fact cane sugar was shipped from such places as the Phillipines and South America.
It was remembered how difficult sugar was to obtain during the WWI, so Americans began stockpiling sugar in 1941. Sugar began being rationed and actually continued being rationed through 1946 until the sugar supply was sufficient to meet demand.
Warmly,
Marion
Proud Daughter of Walter (Monday) Poniedzialek
540th Engineer Combat Regiment, 2833rd Bn, H&S Co, 4th Platoon
There's "No Bridge Too Far"