Regular Thyroid Testing Recommended Regardless of Diabetes Type

Thyroid dysfunction is common among people with diabetes regardless of type, suggesting that biochemical thyroid screening should be a part of routine management for those with type 1 and type 2. A recent study has determined the prevalence and incidence of thyroid dysfunction in type 1 diabetes, type 2 diabetes and latent autoimmune diabetes of adults.

The American Diabetes Association (ADA) recommends universal screening for thyroid dysfunction in type 1 diabetes. The ADA previously recommended thyroid screening for women aged at least 50 years with type 2 diabetes; however, the current ADA guideline and that of the UK National Institute for Health and Care Excellence do not recommend thyroid function monitoring in type 2 diabetes.

Scientists at the University of Western Australia Medical School (Fremantle, Australia) in an observational study, analyzed data from 1,617 adults participating in the Fremantle Diabetes Study Phase II, including 130 (8%) with type 1 diabetes, 1,408 (87.1%) with type 2 diabetes and 79 (4.9%) with latent autoimmune diabetes in adults (LADA). The team assessed thyroid-stimulating hormone (TSH) and free thyroxine at baseline between 2008 and 2011 and in those attending follow-up at four years.

The investigators reported that the prevalence of known thyroid disease was 11.7% (189/1,617). Of the remaining 1,428 participants, 5.1% (73/1,428) had biochemical evidence of subclinical hypothyroidism, 1.1% (15/1428) overt hypothyroidism, 0.1% (2/1428) subclinical hyperthyroidism and 0.2% (3/1428) overt hyperthyroidism, representing an overall baseline prevalence of thyroid disease of 17.4% (282/1,617). During 5,694 patient‐years of follow‐up, 25 (3.0%) of the 844 with a normal baseline TSH and follow‐up data developed known thyroid disease. Of the remaining 819, 3.4% developed subclinical hypothyroidism, 0.2% overt hypothyroidism and 0.5% subclinical hyperthyroidism.

Paul Chubb, PhD, FFSc (RCPA), an adjunct associate professor and a co-author of the study said, “The prevalence of thyroid disease is about the same regardless of the type of diabetes, mainly because the average age of people with type 2 diabetes was higher than that of those with type 1 diabetes. However, we also found that mild abnormalities of thyroid function test results were frequently transient, so that appropriate repeat testing and careful interpretation of the results is needed if overdiagnosis is to be avoided.”

The authors concluded that thyroid dysfunction, known or detected through screening, is common in diabetes. These data suggest the need for periodic clinical and biochemical screening for thyroid disease in all types of diabetes. The study was published on January 27, 2020 in the journal Clinical Endocrinology.

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University of Western Australia Medical School