Study associates iodine deficiency with type 2 diabetes
Astute clinicians are cautious with iodine supplementation due to the risk for triggering latent thyroid autoimmunity, but a study just published in the journal Experimental and Clinical Endocrinology & Diabetes is a reminder to remain vigilant about the potential need for iodine when managing type 2 diabetes. The authors note:
"Patients with diabetes mellitus are at an increased risk of thyroid disease. The purpose of this study was to examine the urinary excretion of iodine in type 2 DM (T2DM) patients, and to assess the clinical implication of iodine status on T2DM."
They examined data for 266 adult subjects aged 18-55 years, 109 of whom were T2DM patients along with 157 healthy controls, and correlated urinary iodine with anthropometry, fasting glucose, lipid profile; serum concentrations of leptin, adiponectin, resistin, insulin, aPAI, hsCRP, Ang II, TNF-α, TSH, T3, T4, and urine creatinine. There was a marked association of urinary iodine and type 2 diabetes:
"The concentration of urine iodine was significantly lower in T2DM than in healthy control subjects (84.6±2.3 vs. 119.4±3.4), which remained significant after creatinine correction and controlling for age. Furthermore, urinary iodine is negatively correlated with waist, hips, SAD, glucose, insulin, HOMA-IR triglyceride, resistin, angiotensin II (Ang II), and CRP, while it was positively associated with TSH."
Although care must be taken to avoid potentiating autoimmune thyroiditis by iodine supplementation, physiological deficiencies may contribute to T2DM and other disorders (fibrocystic breast disease among them). These results beg for follow-up studies to determine if repleting iodine improves the T2DM biomarkers while supporting, or at least not harming, thyroid function. Meanwhile, this is something that clinicians can monitor carefully with individual patients. The authors conclude:
"The decreased levels of iodine concentration in T2DM patients and its likely deleterious effects on metabolic functions calls for a systematic approach to thyroid disease screening in diabetic patients. Routine annual urinary iodine determination is recommended and should target T2DM patients at risk of thyroid dysfunction."