GAD1 and diabetes mellitus: A study of T2D patients in Hong Kong diagnosed before the age of 40 noted that 4% of patients had autoimmune markers, while half of them had a positive family history and/or obesity, suggesting that genetic factors and obesity play a greater pathogenetic role than autoimmunity.66 Another multicenter study of Asian patients diagnosed with diabetes before the age of 40 noted that only 11.5% were positive for autoantibodies against glutamic acid decarboxylase (GAD) or tyrosine phosphatase (IA-2A).