Type 1 Diabetes and Related Autoimmune Conditions

The other day I met a gentleman with type 1 diabetes for the first time in my office. He had very few complaints and a reasonable hemoglobin A1C, but I noticed that his thyroid levels hadn’t been checked for as far back as I could see. Low and behold, the next day his blood tests revealed that he was extremely low on thyroid hormone. I immediately started him on thyroid hormone supplementation given the long term risk of heart failure in patients with untreated hypothyroidism.

Afterwards, I decided to make sure that readers of this blog are aware of other autoimmune conditions which are associated with type 1 diabetes.

The most common autoimmune condition which occurs alongside type 1 diabetes is hypothyroidism (low thyroid hormone levels), which features symptoms such as fatigue, weight gain, cold intolerance and dry skin. In fact, up to 20% of patients with type 1 diabetes have antibodies directed against the thyroid and approximately 2-5% of these patients will go on to develop clinically significant thyroid disease. Women with type 1 diabetes are more likely to develop hypothyroidism than men, and the prevalence increases with age.  

Type 1 diabetes is associated with various antibodies that target the pancreatic cells, including anti-islet, anti-insulin, and anti-glutamic acid decarboxylase (GAD) antibodies. Patients with GAD antibodies in particular appear to have a higher risk of also developing anti-thyroid antibodies.

 Overt hypothyroidism carries varies risks including heart failure and neurologic dysfunction. However, even mild hypothyroidism can results in adverse outcomes including abnormal growth in children and an increased risk of symptomatic hypoglycemia. Accordingly, thyroid levels should be checked several weeks after the diagnosis of type 1 diabetes is made.

Testing should be delayed until patients’ sugars are reasonably controlled, since at least 20% of patients may have transient, self-correcting aberrations in thyroid hormone tests at the onset of the diagnosis.  If thyroid levels are normal, they should be rechecked every 1-2 years. If thyroid levels are normal but antibodies are positive, hormone levels should be rechecked annually at a minimum.

Another autoimmune disease which is correlated with type 1 diabetes is celiac disease, which affects roughly 5% of type 1 diabetes patients. This condition is ultimately diagnosed by a small bowel biopsy. Risk factors for the development of celiac disease include female gender, younger age at diagnosis of diabetes, longer duration of diabetes and presence of thyroid disease. In the general population, celiac is associated with gastrointestinal distress, diarrhea and bloating. In contrast, patients with diabetes rarely present with these symptoms. Rather, celiac can manifest with erratic blood sugar control with frequent hyper and hypoglycemic episodes.

All patients with newly diagnosed type 1 diabetes should be screened for celiac disease with antibody testing (particularly “antiendomysial” or “tissue transglutaminase” antibodies). If the antibodies are positive, the patient should have a small bowel biopsy with a gastroenterologist and commence a gluten-free diet as appropriate. If the antibodies are negative, patients should be retested every two years.

Several other autoimmune conditions are less common but are worth mentioning. Rarely, patients with type 1 diabetes have antibodies directed against the adrenal gland, the gland which sits just above the kidneys and produces vital hormones including adrenaline and cortisol. Autoimmune adrenalitis causes adrenal insufficiency and resultant hypoglycemia. Type 1 diabetes can also occur concurrently with a host of autoimmune conditions which present with missing skin pigmentation, hair loss, low sex hormones, and chronic yeast infections, among other symptoms. Together, these are called polyglandular autoimmune syndromes.

If you have type 1 diabetes and have not been screened recently for thyroid disease or celiac, mention to your doctor or health care provider that you would like to have the blood tests done. The odds are you don’t have either condition, but it’s worth checking just to be on the safe side.

American Diabetes Association: Standards of medical care in diabetes—2014. Diabetes Care 2014; 37 Suppl 1:S14.

Mohn et al. The effect of subclinical hypothyroidism on metabolic control in children and adolescents with Type 1 diabetes mellitus. Diabet Med 2002; 19:70.

Kordonouri et al. Thyroid autoimmunity in children and adolescents with type 1 diabetes: a multicenter survey. Diabetes Care 2002: 25: 1346.

Kordonouri et al. GADA positivity at onset of type 1 diabetes is a risk factor for the development of autoimmune thyroiditis. Pediatr Diabetes: 2011: 12:31. 

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