Systemic Immune-Inflammation Index (SII) of Patients With and Without Diabetic Neuropathy: A Cross-Sectional Study

Diabetic neuropathy is a common microvascular complication of type 2 diabetes mellitus (T2DM), like diabetic retinopathy and nephropathy. The neutrophil count is raised during infection and inflammation, and the lymphocyte count is decreased in immunocompromised patients. The platelet count suggests the thrombotic and inflammatory conditions. Hence, the neutrophil-lymphocyte ratio (NLR) is the ratio of absolute counts of neutrophils to lymphocytes. The systemic immune-inflammation index (SII) is the product of NLR and platelet count. These indicate the immuno-inflammatory status of the patient. There is a dearth of literature assessing the SII of individuals with diabetic neuropathy. Hence, we mapped this study to evaluate and compare complete blood count (CBC), NLR, and SII of diabetic patients with and without neuropathy. We also correlated NLR and SII values of the study population.

This cross-sectional study was conducted from April 2024 to March 2025 at Kalinga Institute of Medical Sciences (KIMS), Bhubaneswar, India. We included adult diabetic patients admitted to the KIMS medicine ward. Hemoglobin, total leucocyte count (TLC), neutrophil count, lymphocyte count, platelet count, length of T2DM, and glycated hemoglobin (HbA_1c) were all measured shortly after their hospitalization. NLR was calculated by dividing the absolute neutrophil count by the absolute lymphocyte count. We obtained the SII value by multiplying the platelet count by NLR. R software version 4.4.3 (R Core Team, Vienna, Austria) was used for statistical analysis.

One hundred ninety-three diabetic patients were found eligible for this study. Their median age was 66 (55-73) years. Of them, 92 (47.7%) were women. The study population's median white blood cell (WBC) was 9.88 (8.72-11.24) × 10⁹/L. The median counts of lymphocytes and neutrophils were 2214 (1720-2647)/µL and 6864 (5796-8256)/µL, respectively. The study population's median platelet counts were 250 (189-293) × 10⁹/L. The study population's median HbA_1c was 8.61 (7.57-9.31)%. The study population's median duration of diabetes mellitus was 11 (6-18) years. The study population's median SII and NLR were 755.3 (521.4-1002.2) × 10⁹ cells/L and 2.93 (2.40-4.21), respectively. NLR and SII values were positively correlated (r = 0.92, p < 0.001). Regardless of neuropathy, the association between NLR and SII was identical among the study subjects.

Diabetes patients without neuropathy and those with neuropathy had comparable CBC, NLR, and SII values. The results of our study cannot be extrapolated due to the limited sample size and failure to account for several variables, including concurrent medications, comorbidities, and length of hospital stay.