AN “extremely high level” of insulin was found in a baby boy allegedly poisoned by a nurse, a court has heard.

Lucy Letby, 32, is said to have tried to murder the premature twin by intentionally giving him insulin on the Countess of Chester Hospital’s neonatal unit.

The prosecution say she struck after midnight on a night shift starting on August 4, 2015 as the youngster, referred to as Child F, received a new feed of nutrients via a bag connected to an intravenous line.

Shortly after, his heart rate surged and his blood sugars plummeted, jurors at Manchester Crown Court have been told.

Giving evidence on Thursday, November 24, the shift’s on-call consultant Dr John Gibbs said the sudden rise in heartbeat from a normal rate was “very unusual” and Child F’s blood sugar was “worryingly low”.

It was initially treated as a suspected infection and dehydration but a blood test revealed a week later that a large level of insulin was in his body, the court heard.

Dr Gibbs said: “The fact that (Child F) was found to have an abnormally high level of insulin – in fact an extremely high level – in the blood, in retrospect makes it likely the symptoms he was displaying after midnight were related to a very low blood sugar level caused by him receiving a high dose of insulin.

“I didn’t suspect that at the time because there was no reason why he should have had a high dose of insulin administrated to him.”

Child F had not been prescribed synthetic insulin at the time and checks by the hospital confirmed no other baby on the unit was receiving the medication on August 4 or August 5, the court heard.

Dr Gibbs said he would have expected the laboratory results received from Royal Liverpool Hospital to have shown “virtually” no insulin in Child F’s blood because of his abnormally low blood sugar.

Instead, the levels were high and hormone markers found the insulin could not have been naturally produced by Child F, he said.

Dr Gibbs said: “This shows (Child F) had been given a synthetic form of insulin but he was never prescribed this at this time and he should never have received it.”

Child F was given extra doses of glucose following his rapid change in health but his blood sugar readings stayed low on the day shift of August 5, the court heard.

Dr Gibbs said: “This was unexpected. He had not responded well to the treatment but we didn’t know at this time it was because he had a large dose of insulin inside him.”

Child F’s blood sugars rose from 7pm after the intravenous nutrients were stopped and extra sugar was given independently, jurors were told.

He went on to make a full recovery and was discharged.

Letby is accused of trying to kill Child F less than 24 hours after she allegedly murdered his twin brother, Child E, by injecting air into his bloodstream.

The defendant, originally from Hereford, denies murdering seven babies and the attempted murders of 10 others between June 2015 and June 2016.

The trial continues on Friday, November 25.

The Standard will be providing live updates throughout the day.