The prevalence of type 2 diabetes in adults is independently related to decreased free triiodothyronine and free triiodothyronine-to-free thyroxine ratio, and increased free thyroxine concentrations, study data show.
Kaijun Niu, MD, PhD, of the Nutritional Epidemiology Institute and School of Public Health at Tianjin Medical University in China, and colleagues evaluated data from the TCLSIHealth cohort study 2013-2015 on 15,296 adults (8,970 men) to determine whether thyroid hormone levels within the reference range are related to type 2 diabetes.
Overall, the prevalence of type 2 diabetes among participants was higher in men (16.2%) than women (7.7%). Compared with women, men had higher free T3 and free T4 levels (P < .0001 for both). However, thyroid-stimulating hormone levels were lower in men compared with women (P < .0001).
Compared with participants without diabetes, those with diabetes were older; had higher BMI, waist circumference, total cholesterol, triglycerides, and systolic and diastolic blood pressure; were more likely to have a family history of hyperlipidemia and diabetes; and had lower HDL levels (P < .01 for all). Men with diabetes had lower free T3 levels and free T3/free T4 ratio and higher free T4 levels compared with men without diabetes (P < .05 for all). Compared with women without diabetes, women with diabetes had higher LDL and free T4 levels and lower free T3/free T4 ratios (P < .01 for all).
Among men, gradual increases in free T3, free T3/free T4 ratios and TSH concentrations were related to the adjusted ORs of type 2 diabetes compared with men with the lowest concentrations of thyroid hormones.
“Decreased [free] T3, [free] T3/[free] T4 ratios and increased [free] T4 levels were independently related to the prevalence of [type 2 diabetes] among the adult population,” the researchers wrote. “[A] significantly negative relationship between TSH and [type 2 diabetes] was observed in males, but not in females. Future studies should be aimed at clarifying cause and effect relationship between [thyroid hormones] and [type 2 diabetes].” – by Amber Cox
Disclosure: The researchers report no relevant financial disclosures.