One of the interesting things to me about pubmed is that it sorts articles by newest to oldest automatically, and makes it easy for me to compare old articles and new articles.
Almost all articles on the topic of diabetes and ABO antigen blood types published before 1985 found no relationship. All of the articles I found published after 1990 found a relationship between ABO blood group and risk of type 2 diabetes. From reading these, my conclusion is:
Blood type B is protective against obesity related type 2 diabetes, particularly as compared to type O and type A blood types.
Some people with type A blood have a particular form of the allele that, when homozygous, raises risk of type 1 diabetes.
Having a blood type that is different from your mother's blood type is a risk factor for multiple autoimmune diseases, including type 1 diabetes.