Low T3 syndrome is associated with peripheral neuropathy in patients with type 2 diabetes mellitus

Diabetic peripheral neuropathy (DPN) is one of the most common chronic complications of diabetes mellitus. Diabetic patients often have thyroid dysfunction. The aim of this study was to investigate the association between low triiodothyronine (T3) syndrome and DPN in patients with type 2 diabetes mellitus (T2DM).

A retrospective review was performed of 928 patients with T2DM for whom data was available for clinical manifestations and nerve conduction studies (NCS), and of 134 non-diabetic controls. The composite Z scores of conduction velocity and amplitude were calculated. Low T3 syndrome was defined as T3 levels below the lower limit of the reference interval.

Among the patients with T2DM, 632 (68.1%) had DPN, and a larger proportion of these patients presented with low T3 syndrome than patients without DPN. After adjusting for potential confounders, low T3 syndrome was independently associated with the occurrence of DPN (odds ratio [OR] = 2.049, 95% confidence interval [CI] 1.319-3.181, p = .001) and the severity of DPN (OR = 1.597, 95% CI 1.030-2.476, p = .036). Adding the criterion of low T3 syndrome improved the prognostic performance of the traditional model (age + gender + diabetic duration + glycated hemoglobin [HbA1c]) for predicting DPN.

Low T3 syndrome is associated with a higher risk and increased severity of DPN in patients with T2DM. These findings suggest that low T3 syndrome could be a predictor for risk stratification in patients with T2DM.