But Treadwell suffered from a hypoglycaemic episode resulting from his blood sugar levels dropping dangerously low.
As a result, Treadwell started losing control of his Vauxhall Corsa and swerved onto the other side of the road, Ipswich Crown Court heard.
His car then smashed into an oncoming Ford Fiesta driven by Aironas Gzimaila, 23, who was from Harwich. Mr Gzimaila was killed in the collision.
Treadwell, who admitted causing death by careless driving, was also seriously injured in the crash and was taken to hospital.
The court was yesterday shown dash cam footage of the accident but Treadwell was allowed to leave the dock.
The court heard the 31-yearold had failed to regulate his blood sugar levels responsibly, resulting in the hypoglycaemic episode – known as a hypo – taking place.
Richard Kelly, prosecuting, told the court that, in line with DVLA advice, diabetics must test their blood sugar levels every two hours when they are driving.
Although Treadwell did test his blood sugar levels on the day of the fatal collision, analysis from the blood glucose meters recovered from his car showed that Treadwell was aware he was at risk of having a hypo whilst at the wheel.
Treadwell, of Landgon Hills, Basildon, tested himself at 1.31pm and despite having very low blood sugars, did not test himself again and set off to Harwich at around 6.30pm that evening.
At 8.15pm, Treadwell stopped at a Shell garage in Marks Tey where he bought two cans of Red Bull to boost his sugar levels but he blacked out when he suffered from a hypo just half an hour later.
Mr Kelly said: “This is a man who has for years mismanaged the control of his diabetes.
“There’s no compulsion on diabetics to manage their diabetes – that’s up to him as a diabetic – but there is a duty of care when someone gets behind the wheel.”
Treadwell was disqualified from driving immediately and will be sentenced in March.
This content was originally published here.