A diabetic Casey Johnson might have died because she was too drunk to inject herself with insulin

The sudden death of Johnson and Johnson heiress Casey Johnson could be linked to diabetes, a police source says.

“She was still suffering from diabetes and she was still on diabetic medications,” the insider tells People magazine. “The speculation is she came home after a night of partying and passed out without taking her meds or her insulin and that was the end of her.”

Johnson, who had drug abuse problems, was found dead in her Los Angeles home on Monday. It is thought she might have been dead for at least three days before a housekeeper made the grim discovery.

Sources say the 30-year-old socialite’s life had been spiralling out of control amid a series of drunken binges and erratic behaviour.

She had reportedly refused many offers to go into rehab for drug abuse leading her billionaire father, Robert, to cut her out of a trust fund.

Last month, her mother, Sale, took custody of a three-year-old girl that Casey had adopted from Kazakhstan in 2007.