Causes & What We Know/August 2, 2026/3 min read

Many People with Type 1 Diabetes Have Multiple Autoimmune Conditions—But They Often Go Undiagnosed

A new study reveals that people with Type 1 diabetes and thyroid disease or celiac disease frequently have other autoimmune conditions that are never formally recognized or documented.

PubMed indexed literature

Evidence label explains the kind of source behind this article (for example peer-reviewed literature vs community video). It is not medical advice.

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Key takeaways

About one in three people with Type 1 diabetes also have thyroid disease or celiac disease, which qualifies them for a diagnosis called autoimmune polyendocrine syndrome (APS).
Most people meeting the criteria for APS are never formally diagnosed with it, even though guidelines recommend screening for these conditions.
When people with Type 1 diabetes and thyroid or celiac disease undergo extended screening for other autoimmune diseases, about 39% show signs of additional autoimmune conditions they didn't know they had.
Nearly one in three people with Type 1 diabetes who also have thyroid or celiac disease are eventually found to have at least three autoimmune diseases total.
Better recognition and formal documentation of APS in people with Type 1 diabetes could help guide decisions about screening for other autoimmune conditions.

Type 1 Diabetes Doesn't Travel Alone

People with Type 1 diabetes are at higher risk for other autoimmune conditions—diseases where the immune system mistakenly attacks the body's own tissues. The two most common are autoimmune thyroid disease (where the immune system damages the thyroid) and celiac disease (where gluten triggers an immune response in the small intestine). When someone has Type 1 diabetes plus at least one of these conditions, they meet the criteria for a condition called autoimmune polyendocrine syndrome, or APS.

Current medical guidelines recommend that all people with Type 1 diabetes be screened for thyroid disease and celiac disease. However, when these screening tests come back positive, there's often unclear guidance about what happens next—should doctors look for even more autoimmune diseases?

The Study: What Researchers Found

Researchers looked at 639 adults with Type 1 diabetes and found that 198 of them (31%) had Type 1 diabetes plus thyroid disease and/or celiac disease—meaning they met the criteria for APS. Yet only 17 of those 198 people (8.6%) had APS formally documented in their medical records. This suggests APS is frequently overlooked, even when a person clearly qualifies for the diagnosis.

The researchers then invited 139 of these patients to undergo extended screening for additional autoimmune conditions. The results were striking: 39% showed signs of autoimmune diseases they hadn't previously been diagnosed with, and 11.5% received new formal diagnoses. Overall, about one in three patients in this screening group (32%) ended up having at least three autoimmune diseases.

Why This Matters

Formally recognizing and documenting APS in medical records is more than just a label. It signals that a person may benefit from broader screening for autoimmune conditions beyond the standard thyroid and celiac disease tests. Early detection of additional autoimmune disorders can help people and their care teams manage their health more completely.

The study highlights a gap between current screening recommendations and real-world practice. Many people with Type 1 diabetes who meet the criteria for APS are never formally diagnosed, and many with APS may have additional undetected autoimmune conditions. Improving recognition of APS—and clarifying when extended screening is appropriate—could help more people get answers about their health.

Evidence label

Source: Endocrine. 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.

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.

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