First Large Study in Japan Identifies Early Signs of Type 1 Diabetes in Relatives

Researchers at 71 medical centers across Japan conducted the first large epidemiological study of presymptomatic Type 1 diabetes among family members. They screened 2,614 first-degree relatives of people already diagnosed with Type 1 diabetes for islet autoantibodies (IAbs)—immune proteins that indicate the body is attacking its own insulin-producing cells. This screening approach helps identify people who have begun the disease process but have not yet developed symptoms or blood sugar problems.

Nearly 4% of relatives tested positive for at least one autoantibody. Among those positive, 16 relatives (0.6% of the total screened) carried multiple autoantibodies, which typically signals a higher risk of progression. The most frequently detected autoantibodies were ZnT8A, found in roughly half of positive cases, and GADA, present in 42% of positive individuals. These findings align with patterns observed in other countries, suggesting that the biological markers of Type 1 diabetes risk appear similarly across different populations.

Among the 95 autoantibody-positive relatives, researchers classified participants into presymptomatic stages based on glucose tolerance testing. Five met criteria for stage 1, nine for stage 2, and two for stage 3—each representing a different point along the disease progression before symptoms develop. The study also examined genetic markers associated with Type 1 diabetes susceptibility. Certain HLA alleles and haplotypes—groups of genes inherited together—were more common in autoantibody-positive relatives, consistent with known genetic risk factors for the disease.

This is the first study to systematically describe presymptomatic Type 1 diabetes characteristics in Japan and Asia as a whole. By showing that autoantibody prevalence in Japan matches rates in other countries, the findings underscore that Type 1 diabetes risk screening and monitoring is relevant and important in Japanese populations, just as it is elsewhere. The researchers note that further long-term studies tracking autoantibody-positive individuals are needed to build effective screening and monitoring systems that could eventually help prevent or delay Type 1 diabetes onset in at-risk relatives.

Source: Diabetes research and clinical practice. Evidence type: PubMed indexed literature. Type1Cure is an information and intelligence hub, not a medical advice service. This article summarizes published research and does not provide diagnosis, treatment, or personal medical guidance. Always talk to your own care team before changing anything about your Type 1 diabetes management.