Sufficient iodine intake is “critically important” for reducing frailty risk in patients with type 2 diabetes (T2D), especially those with potential thyroid dysfunction, according to a population-based cohort study published in the Journal of Nutrition, Health and Aging.
“Previous studies have shown that iodine deficiency was associated with adult blood glucose, blood pressure, and blood lipids. Low urinary iodine concentration (UIC) increases the risk of dyslipidemia, hypertension, and coronary artery disease,” wrote Yingli Lu, MD, PhD, and colleagues. “The direct relationship between iodine nutritional status and frailty remains unexplored in diabetes.”
Therefore, researchers investigated the link between iodized salt consumption and frailty, examining whether markers of thyroid function could modify the relationship.
The study authors sourced data from the METAL study, which included adults with T2D from Shanghai, China. The analysis included 850 patients with 5 years of follow-up as of 2023. Participants were excluded if they lacked data on the type of salt they consumed, urinary iodine levels, or frailty assessments.
The researchers reported the following:
› Iodine intake and frailty: Patients consuming non-iodized salt had a higher risk for frailty compared with those using iodized salt. Lower UIC was also associated with increased frailty risk.
› Thyroid function stratification: The association between poor iodine status and frailty was only significant in patients with elevated thyroid-stimulating hormone (TSH) and low free thyroxine (FT4). The researchers found no association between low TSH and high FT4.
› Gait speed impact: Researchers reported that gait speed was the most sensitive frailty component affected by iodine status.
› Low UIC levels: UIC in those with diabetes (median 139.7 μg/L) was notably lower than the general adult population (176–178 μg/L), with 50.5% of patients with T2D reporting consumption of non-iodized salt.
The study had several limitations, including some self-reported data, a lack of baseline frailty exclusion, and a lack of data on long-term iodine status. In addition, more research is needed to confirm the findings in broader populations.
“Our finding implied the possible beneficial effect of iodine supplementation in reducing the risk of frailty in diabetes, especially in patients with a lower FT4 or higher TSH level,” the researchers concluded.
