Association of the systemic immune-inflammation index (SII) and severity of diabetic ketoacidosis in patients with type 1 diabetes mellitus: a retrospective cohort study

Background: Diabetic ketoacidosis (DKA) is the most serious metabolic complication of type 1 diabetes mellitus (T1DM). Insulin deficiency and inflammation play a role in the pathogenesis of DKA. The authors aimed to assess the systemic immune-inflammation index (SII) as a marker of severity among T1DM patients with DKA and without infection. Methods: The authors included T1DM patients older than or equal to 12 years hospitalized because of DKA. The authors excluded patients with infection or any condition that can change SII parameters or cause metabolic acidosis. The authors compared SII, neutrophil-lymphocyte ratio (NLR), and platelet-lymphocyte ratio (PLR) between severe and non-severe DKA groups. The authors also assessed the need for an ICU, length of stay, and 90-day readmission rate between the groups. Results: The study included 241 patients with a median age of 17 (14, 24) years, and 44.8% were males. More patients with severe DKA (45%) required ICU admission (P<0.001). Median SII increased with DKA severity, and the difference was significant (P=0.033). No significant difference was observed as regards median NLR or PLR (P=0.380 and 0.852, respectively). SII, but not NLR or PLR, had a significant negative correlation with PH (r=-0.197, P=0.002) and HCO3 level (r=-0.144, P=0.026). Also, being in the highest SII quartile was an independent risk factor for DKA severity (OR, 2.522; 95% CI, 1.063-6.08; P=0.037). The authors estimated an SII cut-off value of 2524.24 to predict DKA severity with high specificity. Conclusion: Elevated SII is a risk factor for DKA severity in T1DM. It is better than NLR and PLR in prognosticating DKA patients. These findings highlight the role of inflammation in DKA. SII can help as a valuable and simple tool to assess DKA severity.