Relationship between neutrophil to lymphocyte ratio and diabetic peripheral neuropathy: a systematic review and meta-analysis

BACKGROUND: The present study aims to review the existing scientific literature on the role of neutrophil to lymphocyte ratio (NLR) in diabetic peripheral neuropathy (DPN) to perform a meta-analysis on the available data. METHODS: The electronic repositories Web of Science, PubMed, and Scopus were systematically explored starting from their establishment up until June 9, 2022. RESULTS: Fifteen articles were included in the meta‐analysis after multiple screening according to the PRISMA guidelines. The combined findings indicated that individuals with DPN had higher levels of NLR in comparison to those without DPN (SMD = 0.61; CI 95% = 0.40–0.81, p < 0.001). In the subgroup assessment based on ethnicity, it was observed that diabetic patients with DPN exhibited increased NLR levels in contrast to those without DPN in studies conducted in India (SMD = 1.30; CI 95% = 0.37–2.24, p = 0.006) and East Asia (SMD = 0.53; CI 95% = 0.34–0.73, p < 0.001) but not in studies conducted in Turkey (SMD = 0.30; CI 95% = − 0.06–0.67, p = 0.104) and Egypt (SMD = 0.34; CI 95% = -0.14–0.82, p = 0.165). The pooled sensitivity of NLR was 0.67 (95% CI = 0.49–0.81), and the pooled specificity was 0.70 (95% CI, 0.56–0.81). The pooled positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio (DOR) of NLR were 2.30 (95% CI = 1.71–3.09), 0.45 (95%CI = 0.30–0.67), and 5.06 (95% CI = 3.16–8.12), respectively. CONCLUSION: NLR serves as a distinct marker of inflammation, and its rise in cases of DPN suggests an immune system imbalance playing a role in the development of the disease. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s40001-023-01479-8.