One sentence that was burned into my brain when I was diagnosed in the 90s was that I would "very likely" later pass my type 1 diabetes on to my children. At that time I accepted that and at the age of 10 years I didn’t think much more about it. But how likely is it really to inherit type 1 diabetes?
What is the probability of inheriting type 1 diabetes?
"Most likely," what does that mean anyway? What is the probability that people with type 1 diabetes will pass on the diabetes to their children?
First of all, the wording is actually wrong, because it is not the diabetes that is inherited, only the genetic disposition, i.e. the predisposition to possibly develop diabetes, can be inherited.
Whether it actually happens is another story. So many possible causes that lead to a type 1 diabetes diagnosis are suspected, for example environmental influences such as food or viral infections.
It’s also interesting to note that about 90% of all people with type 1 diabetes have no family history of type 1 diabetes at all. Me neither. But when you start thinking about family planning, the heredity of diabetes becomes more important.
Gender plays a role in inheriting type 1 diabetes
...and this does not refer to the sex of the child, but to the sex of the parent living with diabetes. If diabetes already runs in the family, this is associated with an increased risk of the child developing diabetes.
Important to know: As a parent you cannot influence whether diabetes happens! So it makes no sense to blame yourself! In general, children whose parents or siblings have diabetes have a 3-8% risk of developing the disease (compared to 0.3% in the general population)
If the father has diabetes
...then the risk that the offspring will also get type 1 diabetes is 2-3 times higher compared to when the mother has type 1 diabetes.
If both parents have diabetes
...the risk for type 1 diabetes increases to 10-25%.
If siblings have diabetes
...the risk of type 1 diabetes increases to 10% (25-50% in the case of identical twins).
Lab tests can detect special antibodies in the blood (even years before the blood sugar level rises, antibodies against the insulin-producing cells of the pancreas (beta cells) are present in the affected persons).
The detection of antibodies indicates that inflammatory processes take place in the pancreas, which eventually leads to the destruction of the insulin-producing beta cells. Thankfully, for those relatives of a person with type 1 diabetes where no antibodies can be detected, the risk of developing type 1 diabetes is less than 1%.
Do I really want to know?
However, the question that should be asked when performing the test is whether you really want to know the result? Because even if there is a risk, no effective prevention measures have been identified yet.
Good to know: Type 1 diabetes is a disease where many different genes play a role. Currently, more than 50 disease-relevant gene loci are known to have an influence on the immune response.
One gene that stands out in particular is the HLA gene. The HLA gene (Human Leukocyte Antigens) mediates the strongest risk for the disease. More information on early detection can be found in the Freder1k study or the Fr1da study, among others.