EXPRESS: Relation Between Thyroid Hormones Levels and Diabetic Peripheral Neuropathy in Diabetic Patients without Clinical Thyroid Dysfunction A Systematic Review and Meta-analysis.

The relation between diabetes and thyroid dysfunction is multidimensional. The present study aimed to critically revise the published literature on the relation between thyroid hormone levels and diabetic peripheral neuropathy (DPN) in Type II diabetes (T2DM) patients without clinical thyroid dysfunction. The present systematic review was performed in line with recommendations of the Preferred Reporting Items for Systematic review and Meta Analyses (PRISMA) guidelines. The review was conducted on 10 studies including 7559 patients. They comprised 2892 patients (38.3 %) with DPN and 4667 patients (61.7 %) without DPN. Pooled analysis revealed significantly lower FT3 levels in patients with DPN as compared to patients without DPN [SMD (95% CI): -1.03 (-1.80, -0.25), p=0.009]. Also, it was shown that patients with DPN had significantly lower FT4 levels when compared with patients without DPN [SMD (95% CI): -0.27 (-0.50, -0.05), p=0.02]. However, no significant differences were found between the studied subgroups regarding pooled TSH levels [SMD (95% CI): 0.21 (-0.08, 0.55), p=0.15]. Conclusively, in T2DM patients without clinical thyroid dysfunction, patients with DPN had significantly lower FT3 and FT4 levels while TSH levels were comparable between patients with DPN and patients without.