I have had type 1 diabetes now for 45 years and would like to know why no one in my family, immediate, and extended has it. Did I get it by an autoimmune attack on my pancreas, or by a virus or something since it doesn’t seem to be hereditary?

Long term studies on identical twins made it clear some years ago that the development of type 1A (autoimmune) diabetes had both a genetic and an environmental component. Most new onset cases diabetes do not have a family history, unlike type 2, and this is because predisposition to this condition is mainly dependant on the contribution of HLA antigen genes from both parents.

Clearly also, the impact of environmental factors is erratic, the more so because we don’t yet really understand what they are. Early exposure to certain kinds of cow’s milk has a following and certainly some enteroviruses may play a role although mostly viruses act by accentuating an already established autoimmune process. Even tapeworms may be implicated, but we really don’t yet understand this aspect of type 1 diabetes.The uncertain balance of both these factors explains the frequent absence of a family history.

There is another aspect to your story which is that when you were first diagnosed some 40 years ago when antibody testing was really not available so that it is just possible that you have type 1B diabetes, which is actually rather uncommon in Caucasian families. It is also a condition which is much less clearly understood.

DOB