Two more patients have died at the hospital linked to allegations of sabotage, police said today.
The patients were an 83-year-old man and an 84-year-old woman, Greater Manchester assistant chief constable Ian Hopkins said.
The officer clarified earlier reports which had suggested a man in his 40s had died. The officer said the patient was in fact still very poorly.
Stepping Hill Hospital confirmed the deaths as police continued to question a nurse arrested on suspicion of the murder of three other Stepping Hill patients.
Rebecca Leighton, 27, was arrested on Wednesday at her home in Stockport, just a mile from the hospital where she worked and where the deaths took place.
Tracey Arden, 44, George Keep, 84 and Arnold Lancaster, 71, are thought to have died following the deliberate contamination of saline solution with insulin.
The Nursing and Midwifery Council confirmed that Leighton had been arrested.
Her registration will be suspended while she remains under investigation, the organisation said.
Police have until early this evening to continue questioning Leighton before they must decide whether to charge her, release her or apply for more time to keep her in custody.
Police stress they are still treating the deaths as unexplained and are expected to give further details about the latest death at a press conference later this afternoon.