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Who may be at Risk?
Some factors may put you at risk of developing Type 1 Diabetes
Overview
Autoimmune type 1 diabetes (T1D) can develop at any age, not only during childhood. While often perceived as a childhood condition, most diagnoses occur in adults, with approximately 62% diagnosed at age 20 years or older.1,2
People with a family history of T1D or with other autoimmune conditions have an increased likelihood of developing the condition compared with the general population.3,9
In adults, autoimmune T1D may be misclassified as type 2 diabetes, which can delay appropriate testing and management.5,6
Family History
Having a relative with type 1 diabetes increases the likelihood of developing the condition:
- First‑degree relatives (parents, siblings, or children) have a substantially higher risk compared with individuals without a family history.3,10
- Second‑degree relatives (grandparents, aunts, uncles, nieces, nephews, cousins, or half‑siblings) also have an increased likelihood compared with the general population, though to a lesser extent.10
Autoimmune Conditions
Autoimmune conditions sometimes cluster within individuals and families. People who already have another autoimmune condition such as Graves’ disease, Hashimoto’s thyroid disease, or Addison’s disease have a higher likelihood of developing type 1 diabetes than the general population.9,12
This is thought to reflect shared genetic susceptibility and immune system pathways across autoimmune diseases.8
Misdiagnosed Diabetes Subtype
In adults, autoimmune type 1 diabetes may present gradually and resemble type 2 diabetes at diagnosis. Research suggests that around 40% of adults with autoimmune T1D are initially diagnosed with type 2 diabetes.5,6
Testing for diabetes‑related autoantibodies can help distinguish autoimmune T1D from type 2 diabetes and may reduce the likelihood of misclassification.11
General Population
Although family history and autoimmune disease increase likelihood, approximately 90% of individuals diagnosed with autoimmune T1D have no known family history of the condition.7
This highlights that autoimmune T1D can occur in anyone.
What is Autoimmune Type 1 Diabetes?
What are the Symptoms of T1D?
Can T1D be detected early?
If you are concerned about diabetes or its symptoms, please speak to your healthcare professional
References
- Atkinson MA, Eisenbarth GS, Michels AW. Type 1 diabetes. Lancet. 2014;383(9911):69-82.
- Gregory GA, Robinson TIG, Linklater SE, et al. Lancet Diabetes Endocrinol. 2022;10(10):741-760.
- Steck AK, Rewers M. Genetics of type 1 diabetes. Clin Chem. 2011;57(2):176–185.
- Insel RA et al. Staging presymptomatic type 1 diabetes. Diabetes Care. 2015;38(10):1964–1974.
- Hawa MI, Kolb HK, Schloot N, et al. Adult-onset autoimmune diabetes in Europe. Diabetes Care. 2013;36(4):908–913.
- American Diabetes Association. Classification and diagnosis of diabetes. Diabetes Care. 2025;48( 1):S27–S49.
- Sims EK, Besser REJ, Dayan C, et al. Diabetes. 2022
- Frommer L, Kahaly GJ. Type 1 diabetes and autoimmune thyroid disease—The genetic link. Frontiers in Endocrinology. 2021.
- Ludvigsson JF, Ludvigsson J, Ekbom A, et al. Diabetes Care. 2006;29(11):2483-2488
- Parkkola A, Härkönen T, Ryhänen SJ, et al. Extended family history of type 1 diabetes and phenotype and genotype of newly diagnosed children. Diabetes Care. 2013;36(2):348‑354.
- Winter WE, Pittman DL, Jialal I. Practical Clinical Applications of Islet Autoantibody Testing in Type 1 Diabetes. J Appl Lab Med. 2022;7(1):197-205.
- Edelman SV, Agardh D, Cui N, et al. Risk of new-onset type 1 diabetes in individuals with celiac disease and thyroid disease-An observational study. Diabetes Obes Metab. 2025;27(8):4229-4238.