Zinc transporter 8 (ZnT8) is an islet beta-cell secretory granule membrane protein recently identified as an autoantibody antigen in Type 1 Diabetes. ZnT8 autoantibodies are present in around 65 to 80% of children with recently diagnosed Type 1 Diabetes and 20% to 40% of adults with Type 1 diabetes. ZnT8 antibody complements GAD-65, IA-2, and insulin antibodies as it is positive in 3% to 4% of patients who are negative for GAD-65, IA-2, and insulin antibodies. Use of these 4 antibodies results in 93% to 98% sensitivity. ZnT8 antibody testing can be considered for clinical distinction of Type 1 from Type 2 Diabetes Mellitus, identification of individuals at risk of Type 1 Diabetes (including high-risk relatives of patients with diabetes, and those with Gestational Diabetes) & prediction of future need for insulin treatment in adult-onset diabetic patients.