Welcome to our forum, Characteristics. There are many many variations with diabetes and that's one of the reasons it's so hard to get a correct diagnosis. There is definitely a hereditary component. When your medical professional takes your history, that's why they ask if anyone in your family has diabetes - because it puts you at higher risk yourself.
Type 1 is no longer referred to as "juvenile diabetes". People in middle age have been diagnosed as being type 1. There are specific tests to determine this, one being the C-peptide test which tells if the pancreas is producing insulin, and if it is not, then the patient is type 1.
It may be less likely that children are found to be type 2, but even that risk in increasing what with the outbreak of childhood obesity.
I want to emphasize that
eating carbohydrates is not the cause of diabetes. While ingesting large amounts of carbs exacerbates the symptoms of diabetes - elevating blood glucose . . . the causes of diabetes remain a mystery at this time, there is no cure at this time, and we do not bring it on ourselves, although our lifestyle can have an affect on how quickly it develops (and none of this applies to type 1 diabetes).
One good resource for basic diabetes information is found at
BloodSugar101.