Diabetes diagnosis not always straight forward in kids

The increasing heterogeneity of diabetes in children and adolescents poses diagnostic dilemmas for the unwary, a meeting of the Royal College of Pathologists of Australasia (RCPA) was told recently.

Speaking to the limbic after her presentation at the RCPA’s Pathology Update in Sydney, Professor Maria Craig said paediatric diabetes was certainly a case of ‘the more we look, the more we find’.

“We can’t always assume it’s type 1 diabetes in a child,” she said.

“Certainly up to 10% of adolescents can have type 2 diabetes – especially those in high-risk ethic groups such as indigenous Australians and Pacific Islanders – while 2 to 4% of children will have a form of monogenic diabetes.”

Professor Craig, a paediatric endocrinologist at the Children’s Hospital Westmead, said overweight was common in children presenting with both type 1 and type 2 diabetes.

“An overweight child negative for autoantibodies looks like type 2 diabetes and probably is type 2 diabetes but genetic tests can throw up a diagnosis of maturity-onset diabetes of the young (MODY).”

Additional clinical features that should raise suspicions and warrant genetic testing for monogenic diabetes include seizures and hearing loss.

She warned there did not have to be a family history as monogenic diabetes could be due to a new mutation.

On the other hand, it was not uncommon for a diagnosis of monogenic diabetes in a child to raise questions about diabetes in their otherwise undiagnosed parents.

Professor Craig said most commercial diagnostic laboratories typically tested for islet cell cytoplasmic (ICA) autoantibodies, insulinoma-associated-2 (IA2) autoantibodies and glutamic acid decarboxylase (GAD) antibodies.

However a fourth test – zinc transporter 8 (ZnT8) antibodies – can help to discriminate some cases of type 1 diabetes.

“In a patient with clinical type 1 diabetes who is antibody negative, think of testing for the fourth antibody as it can be the only antibody present.”

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