Islet Autoantibody Screening Throughout Australia Using In-Home Blood Spot Sampling: 2-Year Outcomes of Type1Screen

Type1Screen offers islet autoantibody testing to Australians with a family history of type 1 diabetes (T1D) with the dual aims of preventing diabetic ketoacidosis (DKA) and enabling use of disease-modifying therapy. We describe screening and monitoring outcomes 2 years after implementing in-home capillary blood spot sampling. Data from 2,064 participants who registered between July 2022 and June 2024 were analyzed: 1,507 and 557 chose blood spot and venipuncture screening respectively. We compared baseline characteristics and outcomes for 1,243 participants (967 blood spot and 276 venipuncture) whose samples were tested by June 2024. One blood spot and five venous participants reported unsuccessful sample collections. The median (quartile 1, quartile 3) age of blood spot registrants was lower (12.1 [7.1, 27.1] vs. 17.2 [9, 38.4] years; P < 0.0001), and a higher proportion lived in regional Australia (39% vs. 29%; P = 0.0037). Among 72 participants (5.9%) with a positive screening test, 5 screened by blood spot and 2 by venipuncture had no autoantibodies on confirmatory testing. Blood spot screening identified the expected 2.1% prevalence of multiple autoantibodies and a 2.5% prevalence of a single autoantibody compared with 1.5% and 4.1%, respectively, for venipuncture screening. Clinical diabetes developed in 12 participants. All had screened positive and none had DKA. Type1Screen has national reach. In-home blood spot screening is feasible, particularly for younger participants living regionally, and identifies the expected prevalence of preclinical T1D. The lower cost, increased convenience, and greater reach of blood spot screening could help meet increasing demand for early T1D diagnosis.