Today on nytimes.com is an article, "Diabetics Confront a Tangle of Workplace Laws," by N.R. Kleinfield. The author describes cases of discrimination towards diabetics at the workplace, and the laws that may or may not protect them. For example, the article describes a UPS worker who, after being diagnosed with type 2 diabetes and starting insulin, was fired because he could no longer obtain an interstate commercial driving license. (At the time, diabetics on insulin were forbidden from obtaining these licenses.) Even though he had not actually needed one of these licenses in the 13 years as a mechanic for UPS, it was company policy and they would not make an exception for him.
I have been fortunate to have very understanding coworkers who accommodate my diabetes graciously. Also, I try to control it in such a way that it interferes minimally with my work. But I can see how these issues could arrive in a work environment different from my own.