A dog trained to smell blood sugar levels saved the life of a seven-year-old boy with type 1 diabetes, his parents said.
When Thomas French, from South Ockendon in Essex, was tested by his parents, his levels seemed fine, but Poppy, a dog from Kent-based charity Hypo Hounds, knew differently.
Poppy became "frantic", Thomas's mother, Jennifer Whiberley, said.
The boy was rushed to hospital with plummeting levels and treated.
"Having a hypoglycaemic attack is common for Thomas as he has no hypo-awareness, which means he is unaware when his blood sugar levels are dropping dangerously low," Ms Whiberley said.
"This is why we qualified for our diabetic alert dog, springer spaniel Poppy, who alerts us when his bloods are going high or low and need correcting.
"But when Thomas's technology devices were telling us his levels were good, Poppy knew otherwise and acted like we have never seen her before."
Thomas had just had his dinner on 1 October when the dog became "frantic", Ms Whiberley said.
"She launched herself off the sofa at dad Jon, barking and circling him in a frantic effort to get his attention.
"Poppy is trained to alert us using her paw for Thomas to check his bloods, so we knew something was wrong when her behaviour was so insistent."
His blood glucose levels were good, but when they tested a short while later, Thomas was "crashing dangerously" and sugary drinks did not help.
His lips were turning blue, his mother said, and he was rushed to hospital in an ambulance.
Once stable he returned home, but Ms Whiberley said Poppy, aged two, would not leave his side.
"She laid on him all day and slept. I think she was unsettled.
"The bond that they share is so strong.
"I truly believe that she has saved Thomas from going into a life-threatening diabetic coma."
Hypo Hounds founder, Jane Pearman, said: "Our dogs continually surprise us – even though we know how smart they are… they sometimes get there before the medical devices do."
Type 1 diabetes is a disorder in which the pancreas is unable to produce insulin. It is characterised by uncontrolled high blood glucose levels and it can be controlled by injecting insulin.
People with the condition have to monitor their blood sugar levels throughout the day.
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