Women with any form of diabetes are at greater risk of having a child with an autism spectrum disorder, new research shows.
That includes women who did not have diabetes before they got pregnant but developed it while carrying their babies, as well as those who had had type 1 diabetes their entire lives.
Autism’s causes remain somewhat mysterious, but in recent years research has pointed toward the the link between the condition, the immune system and the developing fetal brain.
New research from the Kaiser Permanente health system in California suggests that the inflammation, toxic levels of glucose and immune system effects of all kinds of maternal diabetes may increase the child’s risk of autism by as much as two-fold.
Despite the fact that more than two million people in the US have some form of autism – and rates are rising – we still simply aren’t sure what causes many of them.
Research has come a long way, identifying more than 100 genetic links or mutations that seem to increase an individual’s risks of autism, but 85 percent of cases are not explained by these DNA factors.
Most likely, environmental factors interact with these genes and lead to changes that affect the earliest stages of a baby’s brain development.
The most convincing non-genetic factors scientists have studied thus far have been to older parents and premature babies.
After those, researchers are most interested in how oxygen deprivation (for the baby), viruses and diabetes during pregnancy might affect autism risks for a woman’s child.
This is hardly the first study to link diabetes in general to autism.
In fact, just two years ago, lead study author Dr Anny Xian and her team at Kaiser Permanente found that women who were diagnosed with gestational diabetes before they had been pregnant for 26 weeks were at a 42 percent greater risk of having a child with autism than other women were.
They did not find the same risks associated with gestational diabetes diagnosed later on in the pregnancy, but in the new research, Dr Xian’s team discovered that any earlier development of diabetes in the mother seemed to raise risks for autism.
This included pre-existing type 1 and type 2 diabetes, as well as gestational diabetes – though the latter had the most dramatic affect on autism risks.
A baby’s development is complex, and any change to a mother’s body can have consequences for her baby. The relationship goes the other direction, too: hormonal shifts that occur in pregnancy can cause a woman’s insulin sensitivity to change, and for gestational diabetes to develop.
Diabetes of any kind is typically accompanied by an inflammatory immune system response.
Inflammation has been observed in the brains of children with autism as well, suggesting that this may be one of the links between the two conditions.
Some scientists have theorized that autism could be caused more broadly by immune cell disruptions, as evidence mounts that the earliest stages of a baby’s brain development are highly influenced by its mothers’ immune system.
This concept would apply especially to women with type 1 diabetes.
But for a woman with any of the three types of diabetes, keeping her blood glucose levels stable and reasonably low could be crucial to controlling the risks that that their children could develop autism.
At high levels, glucose can actually be toxic to human tissue, including the cells that make up a fetal brain.
Children of mothers that had type 1 diabetes were at more than double the risk of developing autism in the first seven years of their lives that children whose mothers did not have diabetes faced.
Though the increase in risks of autism were less dramatic in relation to other forms of maternal diabetes, they were still at least 35 percent higher than the risks for the children of non-diabetic moms.
Rates of autism also fell among the children of women whose gestational diabetes developed after 26 weeks of pregnancy.
‘These results suggest that the severity of maternal diabetes and the timing of exposure (early vs late in pregnancy) may be associated with the risk of [autism] in offspring of diabetic mothers,’ the authors wrote.