The word 'sugar' has an impressive number of slang usages. It has been used as an euphemism for 'shit' since the Victorian era. In more modern times, it has been used to refer to almost every sort of illegal drug sold in powdered form (LSD, cocaine, heroin). And is has long been used, especially in the American south, as a term of endearment for both males and females, young and old.
But perhaps the most entrenched of slang usages, used from Canada to the American south, is using 'sugar' to mean diabetes. In some areas you may simply have 'Sugar', while in others it is referred to, more clearly, as 'The Sugar'. (e.g. "My Grandma had The Sugar"). In the American south medical surveys often find it prudent to include 'sugar' as a synonym for diabetes, for example, "Do you have a family history of diabetes, or 'Sugar'?" Having lived in the South for most of my life, I don't recall anyone I've ever spoken to who did not know what 'diabetes' was, but in many rural areas, 'sugar' is still the common name of this disease.
By 1999, the Center for Science in the Public Interest was reporting that the average American ate 158 pounds of sugar per year. By 2005 NRH Nutrition Consultants, Inc. reported that it was down to 146 pounds of sugar each year, plus 16 pounds of artificial sweeteners (health kick, anyone?) Is it any surprise that Sugar has become a disease?