Why Genetic Testing Is Urgent

Genetic testing in neonatal diabetes is not a research exercise or a formality for the records. It is the test that decides the treatment, and timing genuinely matters.

In the largest international study, 1,020 babies from 79 countries were tested and a genetic cause was found in 82% of them. Around 38% had a change in one of the two potassium channel genes — and those are the children who can usually be moved off insulin injections onto a tablet taken by mouth.

The size of that change is hard to overstate. Among children with the commonest of these genes, 88% came off insulin entirely, and their average HbA1c — the three-month blood sugar measure — fell from 8.2% on insulin to 5.9% on tablets.

Speed matters for two reasons.

• Children who transfer sooner after diagnosis are far more likely to succeed. In one analysis, those who transferred successfully had been diabetic for an average of 3.4 years, against 18.2 years for those who could not.
• The same gene affects the brain as well as the pancreas in some children. Researchers believe delayed treatment can mean important periods of brain development are missed.

The good news is that testing has become dramatically faster. Before 2005, the typical gap between diagnosis and testing was more than four years. By 2012 it had fallen to under three months.

So this is a reasonable thing to press on, politely and persistently, in the first weeks.