http://www.ameshistory.org/exhibits/ration_items.htm
Rationed Goods in the USA During the Second World War

A wide variety of commodities were rationed during World War II in the United States.
Rationing ended when supplies were sufficient to meet demand.
Rationed Items Rationing Duration

Tires January 1942 to December 1945
Cars February 1942 to October 1945
Bicycles July 1942 to September 1945
Gasoline May 1942 to August 1945
Fuel Oil & Kerosene October 1942 to August 1945
Solid Fuels September 1943 to August 1945
Stoves December 1942 to August 1945
Rubber Footwear October 1942 to September 1945
Shoes February 1943 to October 1945
Sugar May 1942 to 1947
Coffee November 1942 to July 1943
Processed Foods March 1943 to August 1945
Meats, canned fish March 1943 to November 1945
Cheese, canned milk, fats March 1943 to November 1945
Typewriters March 1942 to April 1944
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Why sugar was rationed for so long? Cuba was right there.

I think you question indirectly answered it...

> Rationing ended when supplies were sufficient to meet demand.

Sugar supplies didn't meet demand.  We imported most of our sugar from the Philippines and Hawaii.  Transport boats that would have done that importing were re-tasked.