Genetic Risk for Autoimmune Type 1 Diabetes: Why Screening Should Extend Beyond First-Degree Relatives

Key Takeaways

Understanding the genetic architecture of autoimmune T1D

Autoimmune T1D is a progressive condition in which the immune system systematically destroys insulin-producing beta cells in the pancreas.^2,11

This destruction occurs through distinct stages, beginning with genetic predisposition and environmental triggers, progressing to presymptomatic autoantibody development, and culminating in clinical symptoms requiring insulin therapy.^2,12

Stages of autoimmune T1D^2,12

The genetic component of autoimmune T1D risk has been well-established, with human leukocyte antigen (HLA) markers serving as primary indicators of susceptibility.²

However, the traditional focus on first-degree relatives of patients with autoimmune T1D (parents, siblings, and children) may inadvertently overlook second-degree relatives at elevated risk.^2,5

Risk in first-degree relatives: Well-established but incomplete

First-degree relatives of patients with autoimmune T1D face an 8-15-fold higher risk of disease compared with the general population.^1,2

Risk of T1D in children of parents with autoimmune T1D³

Despite this well-established familial correlation, approximately 90% of new autoimmune T1D diagnoses occur in individuals with no known family history.²

Second-degree relatives: An underrecognized high-risk population

Second-degree relatives of patients with autoimmune T1D face a 2-fold higher risk of disease compared with the general population.⁵

This expanded risk profile reflects the complex genetic nature of autoimmune T1D susceptibility, and assessing family history beyond immediate relatives provides valuable information for risk assessment.^1,5,11

Clinical rationale for expanded screening

Screening programs with broader inclusion criteria have demonstrated remarkable success in preventing diabetic ketoacidosis (DKA) at diagnosis.⁸

Autoimmune T1D ongoing screening programs²

Benefits of diagnosing presymptomatic early-stage autoimmune T1D¹³

Outcomes of Fr1da population-based screening study (128 children previously diagnosed with presymptomatic early-stage T1D between 2015–2022) vs DiMelli study (736 age-matched children diagnosed with incident T1D between 2009–2018):

• DKA represents a serious and potentially life-threatening complication that occurs in up to 70% of individuals diagnosed with symptomatic autoimmune T1D.¹⁴
• The Fr1da study reported a low prevalence of DKA (only 2.5%) presented at stage 3 following prior early-stage diagnosis, which would reduce the burden associated with increased costs to the patient and their family and the healthcare system.^13,15

The psychological and social benefits of early detection

Early diagnosis provides families and caregivers with structured time for preparation. Studies consistently show:^9,10

• Reduced parent and caregiver anxiety at clinical diagnosis
• Improved psychological adaptation to the diagnosis
• Enhanced confidence in self-management
• Lowered risk of trauma associated with emergency presentation

Patient and caregiver education during presymptomatic stages also supports an easier transition to insulin therapy and more durable self-management behaviors.

Expanded screening in clinical practice

HCPs play a pivotal role in implementing expanded screening approaches; however, implementation should align with established guidelines and available resources.¹⁰

• Expanded screening begins with a comprehensive family history that includes second-degree relatives, supported by standardized screening questionnaires to identify individuals who may benefit from autoantibody testing.⁷
• Screening involves measuring multiple islet autoantibodies (IAA, GADA, IA-2A, and ZnT8A), with ≥2 autoantibodies indicating presymptomatic autoimmune T1D requiring structured monitoring and family education.^6,7
• Effective implementation depends on clear communication about benefits, limitations, psychosocial considerations, and follow-up pathways for individuals who screen positive.⁷
• Screening strategies must be tailored to local infrastructure, insurance considerations, and access to specialized diabetes care to ensure appropriate monitoring and continuity of care.^10,16

The path forward: Transforming autoimmune T1D care

• Growing evidence and evolving international guidelines increasingly support expanded screening for autoimmune T1D, highlighting the importance of broader risk assessment.^7,16
• Expanding screening to include second-degree relatives and incorporating comprehensive risk assessment strategies can help identify more at-risk individuals, prevent severe complications, and improve long-term outcomes.⁵

Why does broader screening matter in autoimmune T1D?

The genetic risk for autoimmune T1D extends well beyond first-degree relatives,^2,5 creating opportunities for early intervention and better outcomes through expanded screening approaches.⁸ HCPs who embrace this broader perspective can make a meaningful difference in the lives of patients and families affected by this challenging condition,^7,8,16 transforming the trajectory of autoimmune T1D from reactive crisis management to proactive, preventive care.

Abbreviations

AAs, autoantibodies; ADIR, Antibody Detection Israeli Research; ASK, Autoimmunity Screening for Kids; CASCADE, Combined Antibody Screening for Celiac and Diabetes Evaluation; DIPP, Diabetes Prediction and Prevention; DKA, diabetic ketoacidosis; GADA, glutamic acid decarboxylase antibodies; GPPAD, Global Platform for the Prevention of Autoimmune Diabetes; HbA1c, glycated hemoglobin; HCP, healthcare professional; HLA, human leukocyte antigen; IAA, insulin autoantibodies; IA-2A, insulinoma-associated antigen-2 antibody; JDRF, Juvenile Diabetes Research Foundation; OGTT, oral glucose tolerance test; PLEDGE, Population Level Estimation of T1D Risk Genes; PRiMeD, Precision Individualized Medicine for Diabetes; T1D, type 1 diabetes; ZnT8A, zinc transporter 8 antibodies.

References

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