For adults with type 1 diabetes, families and carers.
Type 1 diabetes occurs when the immune system targets insulin-producing cells. The same underlying tendency can increase the chance of another autoimmune condition. Autoimmune thyroid disease and coeliac disease are among the most common, but pernicious anaemia, vitiligo, Addison disease and others may also occur.
This does not mean every symptom is autoimmune, and it does not justify a broad panel of unplanned tests. Screening should follow current guidance, symptoms and clinical judgement.
Quick answer
The 2026 ADA Standards recommend screening people with type 1 diabetes for autoimmune thyroid disease soon after diagnosis and again when clinically indicated. Adults should be assessed for coeliac disease when symptoms, signs, laboratory findings or clinical suspicion suggest it. Children have more specific screening schedules. Do not start a gluten-free diet or thyroid treatment without appropriate assessment.
Key points
- Autoimmune conditions can cluster, but each needs its own diagnosis.
- Symptoms may overlap with diabetes, stress, anaemia or medication effects.
- Coeliac blood tests can become unreliable after gluten is removed.
- Sudden severe weakness, vomiting or low blood pressure needs urgent assessment.
Autoimmune thyroid disease
Hashimoto thyroiditis can cause tiredness, feeling cold, constipation, dry skin, weight change, low mood or changes in glucose needs. Graves disease may cause heat intolerance, tremor, palpitations, weight loss or anxiety. Symptoms are not specific, so diagnosis requires clinical assessment and blood tests.
The ADA recommends thyroid screening soon after type 1 diabetes diagnosis and repeated testing when indicated. Children and adolescents may be rechecked at intervals based on age, antibodies, symptoms, growth and glucose variability.
Coeliac disease
Coeliac disease is an immune reaction to gluten that damages the small intestine. Symptoms can include diarrhoea, abdominal pain, bloating, weight loss, poor growth, iron deficiency, low bone density or fatigue, but some people have few digestive symptoms. Unexplained hypoglycaemia or variable glucose can occur when absorption changes.
Do not remove gluten before testing unless a clinician advises it. A gluten-free diet can lower antibody levels and complicate diagnosis. A dietitian experienced in both coeliac disease and diabetes can help after confirmation.
Pernicious anaemia and vitamin B12
Autoimmune gastritis can reduce vitamin B12 absorption. Symptoms may include fatigue, a sore tongue, numbness, balance problems or anaemia. Metformin can also contribute to low B12, so clinicians consider the whole picture rather than assuming one cause.
Addison disease and other less common conditions
Primary adrenal insufficiency is uncommon but important. Symptoms can include weight loss, nausea, abdominal pain, severe fatigue, dizziness, low blood pressure, salt craving or recurrent unexplained hypoglycaemia. Vitiligo causes areas of pigment loss and may coexist with other autoimmune disease.
A practical symptom review
Record the pattern
Note when symptoms started, whether they are persistent, and whether they relate to meals, menstrual cycles, medicine changes or illness.
Check ordinary explanations too
Sleep problems, depression, iron deficiency, infection, pregnancy, kidney disease and medication effects can produce similar symptoms. Good assessment avoids both dismissal and overdiagnosis.
Ask what the test would change
Screening is most useful when the result affects treatment, monitoring or referral. Ask which test is being ordered and how to prepare.
Keep diabetes treatment safe during investigation
Do not stop insulin. If poor intake, vomiting or repeated low glucose occurs, use sick-day guidance and contact the diabetes team.
How overlapping symptoms can mislead
Fatigue is a good example. It can accompany underactive thyroid disease, coeliac disease, anaemia, sleep apnoea, depression, kidney disease, infection or glucose that is frequently high or low. Weight change can reflect thyroid disease, reduced absorption, insulin changes, appetite, stress or another medical problem. A single symptom rarely identifies the cause.
Bring trends rather than conclusions to the appointment. Useful details include bowel pattern, menstrual changes, skin or hair changes, palpitations, temperature sensitivity, family history, growth in children, vitamin results and whether insulin needs have changed. A clinician can then choose targeted tests instead of ordering an unfocused panel.
Screening also has timing issues. Thyroid results can be altered by acute illness, and coeliac antibody tests are harder to interpret after gluten has been removed. Vitamin B12 results require context, particularly with metformin use. Ask whether a result should be repeated, confirmed or interpreted with another test before beginning lifelong treatment.
After a diagnosis
Management should join up rather than create separate plans that conflict. A gluten-free diet still needs carbohydrate awareness and nutritional adequacy. Thyroid treatment may alter glucose patterns as hormone levels normalise. Adrenal insufficiency requires specialist education on steroid replacement and illness dosing. Share medication and laboratory changes with the diabetes team so monitoring can be adjusted safely.
Questions for the appointment
Ask which autoimmune conditions are routinely screened for in your age group, which test is being used and whether eating or medicine affects the result. Clarify what symptoms should prompt earlier testing and how often an abnormal or borderline result will be repeated. If a new diagnosis is confirmed, ask who will coordinate it with diabetes care and whether family members need information or testing.
Common mistakes to avoid
- Starting a gluten-free diet before coeliac testing.
- Buying direct-to-consumer antibody panels without clinical interpretation.
- Attributing every symptom to diabetes burnout or glucose.
- Taking thyroid hormone, iodine or adrenal supplements without diagnosis.
- Ignoring unexplained recurrent hypoglycaemia.
Frequently asked questions
Does type 2 diabetes cause the same autoimmune risk?
Not in the same way. Type 2 diabetes is not usually autoimmune, although a person can have type 2 diabetes and an unrelated autoimmune condition. Misclassification of autoimmune diabetes in adults is also possible.
Should everyone with type 1 diabetes avoid gluten?
No. A gluten-free diet is treatment for confirmed coeliac disease, not a routine requirement for type 1 diabetes.
Can thyroid disease change glucose levels?
Yes, thyroid dysfunction can affect metabolism, appetite, weight and insulin needs. The pattern varies and should be reviewed clinically.
When to get urgent help
Seek urgent care for severe weakness, fainting, confusion, persistent vomiting, dehydration, very low blood pressure, severe hypoglycaemia, significant ketones or suspected diabetic ketoacidosis.
The bottom line
Type 1 diabetes increases the chance of some autoimmune conditions, especially thyroid and coeliac disease. The right approach is targeted screening, careful symptom review and confirmed diagnosis, not restrictive diets or supplements based on suspicion alone.
Related Living Diabetes guides
Sources and further reading
- ADA Standards of Care 2026: Comprehensive medical evaluation and autoimmune disease
- ADA Standards of Care 2026: Children and adolescents
- NIDDK: Type 1 diabetes
This article is for general education and does not replace diagnostic testing or specialist advice.