Nahkira Harris, nine, 'wasted away before her parents' very eyes', Peter Joyce QC, for the prosecution, said.
'She had lost one-third of her body weight. They knew the solution but they did not take it. Her death was totally unnecessary. It was totally avoidable. They watched her go downhill because of their own beliefs,' he told Nottingham Crown Court.
Dwight Harris, 32, and his wife, Beverley, 33, of Radford, Nottingham, deny the manslaughter of their daughter between 17 December 1991 and 1 February 1992. They also deny child cruelty.
Mr Joyce said the parents took their daughter to see Mary Phillips, a GP, on 18 December 1991. She diagnosed diabetes and recommended treatment but six weeks later Nahkira was dead. 'The prosecution case is that her death was the criminal fault of her parents,' Mr Joyce added. Dr Phillips said Nahkira needed hospital treatment with insulin and she was admitted to the Queen's Medical Centre, Nottingham.
But the parents told doctors they did not believe in their daughter receiving insulin although they were warned: 'Without insulin your child will die.' The parents discharged her from hospital against the advice of doctors but took her back on 31 January.
Mr Joyce said they ignored advice to return her to hospital and sought homeopathic remedies instead. When Nahkira was eventually returned she was in a coma and later died. Mr Joyce told the jury: 'Whether it is a matter of religious belief or cultural belief does not matter. The parents had been told that without insulin their child would die.'
The jury was told how doctors at the hospital told the Harris couple that insulin was necessary to treat their daughter's diabetes.
Mr Joyce said: 'A doctor explained that she needed treatment at once and she explained to them that insulin was the treatment and the cure.
'It was apparent from conversations between the parents and a doctor that they did not believe in Nahkira receiving insulin.
'They would not leave her bedside. A doctor took considerable trouble to explain that the only treatment for a child with diabetes was insulin. She asked to talk to them away from Nahkira but they would not leave her.'
The jury heard that the couple later claimed to police that they had been inconsiderately treated by doctors at the hospital.
'Be that as it may, they did not take her anywhere else.'
The trial continues today.