Generally, it is believed that those with a family history of diabetes are more at risk of developing diabetes themselves. However, it’s important to remember that genetics is not the sole contributing factor.
Type 1 diabetes
If the father has type 1 diabetes, the child has a 1 in 17 chance of developing diabetes. If a mother has type 1 and gave birth before the age of 25, her child has a 1 in 25 chance; after age 25, it’s 1 in 100. The risk doubles if the mother developed diabetes before the age of 11. If both parents have type 1 diabetes, the child’s chance of having it is between 1 in 10 and 1 in 4.
Roughly 1 in 7 people with type 1 also have a condition called type 2 polyglandular autoimmune syndrome. In this case, a child’s risk of inheriting the syndrome and type 1 diabetes is 1 in 2.
Genes aren’t everything though; identical twins identical genetic sequencing but if one has type 1 diabetes, the other has just a 50% chance of developing it.
It’s also worth bearing in mind that sometimes type 1 diabetes seemingly comes out of nowhere in a person without any relatives who have it.
Type 2 diabetes
If one parent developed type 2 diabetes before the age of 50, the chance of their children developing the disease is about 1 in 7. If type 2 diabetes occurred after the age of 50, this drops to 1 in 13. If both parents have type 2 diabetes, there is a 50% chance their children will also have type 2 diabetes.
While type 2 diabetes is more strongly linked to family history than type 1, environmental factors also play a role. Families tend to have similar eating and exercise habits which, if poor, can increase the risk for all of its members developing diabetes. Poor lifestyle factors learned in childhood may also persist into adulthood, again increasing risk.
Those who are aware that their family history gives them an increased risk of developing diabetes can still reduce their risk through a healthy lifestyle with a good diet and regular exercise and maintaining a healthy weight. Studies show this can delay or even prevent type 2 diabetes.
Source | American Diabetes Association