Serum FT3 levels inversely linked to DPN in euthyroid patients with T2D

Low free triiodothyronine (FT3) is associated with diabetic peripheral neuropathy (DPN) in euthyroid patients with type 2 diabetes (T2D), according to a study.

Overall, 1,422 hospitalized patients with T2D were enrolled in this study. All participants underwent electromyographic examinations, including nerve conduction velocity (NCV), distal motor and sensor latency (DML and DSL), sensory nerve action potential (SNAP) amplitude, and compound muscle action potential (CMAP) amplitude.

Of the patients with T2D, 519 (36.5 percent) could be diagnosed as DPN based on their clinical symptoms and the results of electromyography.

Patients with DPN had a longer duration of diabetes, poorer blood glucose control, and lower BMI levels, as well as higher proportions of diabetic retinopathy, diabetic nephropathy, and cardiovascular disease (p<0.05 for all), than those without DPN.

Levels of serum FT3 were significantly lower in patients with DPN than those without (4.08 vs 4.39 pmol/L; p<0.001). Furthermore, FT3 showed an inverse association with the nerve DML and DSL and a positive association with the CMAP, SNAP, and NCV of all nerves (p<0.05 for all).

The inverse relationship between serum FT3 and DPN risk persisted even after multivariate adjustment for potential confounders (p<0.05). A causal effect of serum FT3 on the risk of DPN was also noted in a Mendelian randomization analysis.