Prevalence and Clinical Significance of Subclinical Hypothyroidism in Diabetic Peripheral Neuropathy

Abstract

Background and Aim

Diabetic peripheral neuropathy (DPN) is one of the most common and disabling complications of DM. Many studies documented the prevalence of clinical and subclinical hypothyroidism (SCH) in diabetic patients but not in the particular group of patients with DPN. The present study aimed to determine the prevalence of SCH in DPN patients and to evaluate its association with severity of DPN.

Patients and Methods

The present cross-sectional study was conducted on 300 consecutive patients with DPN. The clinical manifestations of DPN were documented according to the validated Arabic version of the Michigan Neuropathy Screening Instrument. Severity of DPN was categorized into mild (6–8 points), moderate (9–11 points) or severe (12+ points) according to the Toronto Clinical Scoring System. All patients were submitted to careful history-taking and full clinical and neurological examination. Patients were diagnosed with SCH if they had TSH level above the upper limit of the normal reference range in association with normal free thyroxine (FT4) level.

Results

SCH was prevalent in 53 patients (17.7%, 95% CI: 13.5%–22.5%). Patients with SCH had significantly higher frequency of severe DPN (52.8% versus 28.3%, p=0.003). It was also shown that patients with SCH had significantly higher HbA1c (8.4 ± 1.0 versus 7.3 ± 1.2%, p<0.001) and HOMA-IR (3.7 ± 0.8 versus 2.7 ± 0.9, p<0.001) when compared with patients without SCH. Logistic regression analysis identified patients’ age [OR (95% CI): 1.06 (1.03–1.08), p<0.001], HbA1c [OR (95% CI): 2.2 (1.7–2.9), p<0.001] and SCH [OR (95% CI): 7.7 (3.6–15.5), p<0.001] as independent predictors of DPN severity.

Conclusion

The present study showed that SCH is highly prevalent in DPN patients and is independently related to its severity.

Keywords:

• diabetes mellitus
• diabetic peripheral neuropathy
• subclinical hypothyroidism
• thyroid hormones
• thyroid dysfunction

Data Sharing Statement

The datasets used and analyzed during the current study are available from the corresponding author on reasonable request.

Disclosure

The authors declare no conflicts of interest, financial or otherwise, in this work.