Nicole Richie's health troubles on the set of The Simple Life – she was hospitalized for dehydration earlier this month – are the result of hypoglycemia, her rep says.

"In her ongoing effort to focus on her well-being, Nicole has recently been diagnosed with hypoglycemia" or low blood sugar, her spokesperson tells PEOPLE in its new issue.

Richie, 25, announced in October that she was seeking treatment for what her rep described as an inability to put on weight.

And though she and Paris Hilton work as counselors at a health camp on the fifth season of their E! reality show, Richie's own physical issues have recently taken center stage.

"Four or five times she's felt really faint and almost passed out," a source tells PEOPLE. "She has to go into her trailer for a good part of the day."

(After her March 2 hospitalization, she reportedly collapsed again on March 14.)

But Richie's rep tells PEOPLE that since Richie got her hypoglycemia diagnosis, "[She] is taking steps to manage it." Adds a show spokesperson: "Nicole has reported to work each day and the results have been fantastic."

Meanwhile, Richie is due to appear in court on April 2 to face misdemeanor drunk-driving charges stemming from a December arrest in Los Angeles. She pleaded not guilty on Feb. 20.