Moore, who was diagnosed with Type 1 diabetes when she was 33, has spent the last couple of years resting at home.
"I don't see her often, but I talk to her a bunch," said Dick Van Dyke, who worked with Moore on The Dick Van Dyke Show. "She hasn't been too well. She's really having a battle with it, I'm sorry to say."
The Mary Tyler Moore Show's Valerie Harper said the disease "does ravage her body, but she stays healthy."
Moore famously depicted a 30-something working woman on The Mary Tyler Moore Show from 1970 to 1977. Her health has reportedly declined in recent years.