No link found between type 2 diabetes and thyroid dysfunction, say Iranian scientists

Having prediabetes or type 2 diabetes did not increase the risk of thyroid dysfunction, a new Iranian study reveals. Scientists from the University of Medical Sciences in Tehran report that thyroid dysfunction was not significantly associated with glucose metabolism. The findings were taken from the Tehran Thyroid Study where prevalence of thyroid dysfunction was recorded in people with impaired glucose metabolism compared to controls. All participants were aged over 30 years. Incidence of thyroid dysfunction was lower among those with type 2 diabetes and prediabetes, but this wasn't significant once adjusted for variables including age, sex, smoking status, blood pressure and BMI. Participants in all three groups who had high baseline levels of serum thyroid-stimulating hormone (TSH) and thyroid peroxidase autoantibodies (TPOAb) were at an increased risk of thyroid disorder over an 11-year follow-up period. "Undetected thyroid disorders may compromise metabolic control of patients with diabetes, [impaired glucose tolerance], or [impaired fasting glucose], and may increase the risk of cardiovascular disease," said the researchers, who added that "diabetes and prediabetes can affect thyroid tests. "Considering the fact that thyroid screening tests are currently recommended only for high-risk groups, i.e. infants, pregnant women and the elderly, conducting these tests in diabetics and prediabetics requires further investigation." The researchers suggest that further studies should be conducted to repeat thyroid tests within 1-4 months of the initial test. "A cohort study with a larger sample size and longer follow-up period is recommended to focus on the assessment of [thyroid dysfunction] in diabetics and prediabetic to gain more insight into this topic," they concluded. The results appear online in the journal PLOS.

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