The Role of the Neutrophil-to-Lymphocyte Ratio in Patients with Diabetes and Atrial Fibrillation: Insights from the National Spanish Registry Sumamos-FA-SEMI

Aim: To analyse the importance of inflammation in the disease burden and prognosis of patients with type 2 diabetes (T2DM) and atrial fibrillation (AF). We assessed these patients according to their neutrophil-to-lymphocyte ratio (NLR) values, examining their baseline characteristics and their prognosis at one year of follow-up based on a prospective AF registry in Spain (Sumamos-FA-SEMI). Methods: A prospective, multicentre, observational study of patients with AF (Sumamos-FA-SEMI) was conducted. We categorised the patients into four groups according to the presence of T2DM and NLR levels with a reference cut-off point of three. We compared the characteristics of the four groups and evaluated the prognosis using the mean values of all-cause mortality and all-cause mortality plus readmissions during a year of follow-up. Results: We analysed 1071 patients, 482 of whom had T2DM. This group had significantly higher rates of obesity and comorbidities. Groups with an NLR greater than three points had a higher prevalence of cancer, lower HDL cholesterol levels, and more albuminuria. Other inflammatory markers, such as C-reactive protein, were also higher in these groups. Regarding prognosis, groups (both with and without T2DM) with an NLR greater than three had significantly higher mortality, with a higher probability in those without T2DM (HR 3.58, 95% CI: 1.99–6.43, p < 0.00). In terms of mortality and readmissions, only the group without T2DM and with an NLR greater than three had significantly higher mortality (HR 2.19, 95% CI: 1.51–3.19, p < 0.00). Conclusions: Among atrial fibrillation patients, the combination of T2DM and high inflammation (NLR) was linked to higher comorbidity, worse metabolic and kidney disease, and the poorest prognosis. Surprisingly, the highest risk of readmission or death was in non-T2DM patients with higher NLR levels, suggesting that T2DM treatments may mitigate risk.