Adult-Onset Type 1 Diabetes, Other Autoimmune Diseases Linked

Miriam E Tucker

March 27, 2018

CHICAGO, Illinois — The risk of developing 1 or more additional autoimmune conditions rises with age at onset of type 1 diabetes, particularly among women who develop diabetes in adulthood, new research suggests.

Findings from more than 1100 adults with type 1 diabetes were presented March 19 here at ENDO 2018: The Endocrine Society Annual Meeting by Yicheng Bao, a medical student at the University of Missouri–Kansas City (UMKC) School of Medicine.  

"Physicians should be aware that a lot of autoimmune diseases can occur in people with type 1 diabetes. People who develop type 1 diabetes in adulthood are at special risk," Bao told Medscape Medical News.

The finding is particularly important in light of the recent UK Biobank study that showed type 1 diabetes onset is equally likely to occur after age 30 years as prior, but is often misdiagnosed as type 2 diabetes in adults.  

Bao noted that previous studies have focused on comorbid endocrine autoimmune conditions, and in children with type 1 diabetes.

In the new study, people with type 1 diabetes onset after age 40 years had twice the risk for 1 or more autoimmune conditions, such as thyroid disease, pernicious anemia, vitiligo, and gastrointestinal autoimmune conditions, as those diagnosed with type 1 diabetes in childhood.

Betty Drees, MD, professor of medicine at UMKC, who was not involved in the study, told Medscape Medical News that she was struck by "the number and variety of [autoimmune] conditions that are outside the endocrine system...I think it has an important clinical message in terms of continuing to monitor adults with type 1 diabetes for late complications that may be associated with autoimmune conditions."

Drees said that although routine screening isn't necessary for autoimmune conditions other than thyroid disease, "I think it's probably more about being very vigilant for symptoms that are early warnings of other autoimmune conditions...Thyroid disease is commonly followed and screened over a lifetime [in people with type 1 diabetes], but some of these other [conditions] may present very subtly. You'd like to diagnose them early and get them treated."

Autoimmunity Rises With Age, Primarily in Women

The study included 1167 adults with type 1 diabetes seen at the Washington University Diabetes Center between 2011 and 2017. Slightly more than half (51.7%) were women and 89.4% were white.

The mean age of participants was 46.9 years and of type 1 diabetes onset was 21.3 years (range 1–78 years). Diabetes onset occurred between ages 31 and 40 years in 12.2%, and after age 41 years in 11.6%.

One or more other autoimmune conditions were present in 35.7% overall, in 47% of women vs 24% of men.

The mean age of type 1 diabetes onset was 20.1 years for those without other autoimmune conditions compared with 23.3 years for those with 1 or more other autoimmune conditions (P = .0003). Moreover, the mean age of type 1 diabetes onset rose with the number of subsequent autoimmune diagnoses, up to 32.3 years for those with 4 or more autoimmune conditions.

In multivariate analysis, the risk for developing additional autoimmune conditions was more than double for those with type 1 diabetes onset after age 40 years compared with onset at 10 years or younger (OR, 2.2; P = .0003).

The prevalence of autoimmune conditions also increased with current age in both men and women, but the rise in women was particularly striking. Women with type 1 diabetes over the age of 60 years had a 63% likelihood of having at least 1 additional autoimmune condition, compared with 33% of men in that age group and 27% of women younger than 29 years (P < .0001).

Many Different Autoimmune Conditions Found

Bao and colleagues screened for 29 different autoimmune conditions. Thyroid diseases were the most common in 26.5% of patients overall, with 21.9% having Hashimoto's hypothyroidism and 5.1% hyperthyroidism. Those conditions were more common among women than men (28.5% vs 14.9% for Hashimoto's).

Other autoimmune conditions identified included pernicious anemia in 4.7% of participants, vitiligo/alopecia in 4.5%, collagen vascular autoimmune disease in 6.7%, gastrointestinal autoimmune disease in 4.4% (with celiac present in 2.6%), immune deficiencies in 1.8%, and neurological diseases (including multiple sclerosis and moyamoya) in 1.5%.

Type 1 Diabetes Usually Diagnosed First

The median age of onset of type 1 diabetes was 18 years, while that of the other autoimmune conditions ranged from 24 to 50 years. "Interestingly, the vast majority of additional autoimmune diseases were diagnosed in adulthood and after the diagnosis of type 1 diabetes. In a small minority of cases other diseases were diagnosed prior to type 1 diabetes," Bao noted.

The median age of onset for Crohn's disease and psoriasis was in the 20s, while lupus, rheumatoid arthritis, and pernicious anemia were diagnosed at median ages of 40, 44, and 50 years, respectively. Other autoimmune conditions were typically diagnosed in people during their 30s.

Drees noted that this scenario calls for coordination between endocrinologists and other relevant medical specialists. "From a clinical standpoint, this is important in raising awareness that if it's not an autoimmune condition within your own practice that you treat, involve other members of the health care team early on so that you provide comprehensive lifelong care."

Bao and Drees have reported no relevant financial relationships.

ENDO 2018. March 19, 2018; Chicago, Illinois. Abstract OR21-3

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