Impact of diabetes on neutrophil-to-lymphocyte ratio and its relationship to coronary artery disease

Background. - Coronary artery disease (CAD) is the leading cause of mortality among diabetic patients, and the neutrophil-to-lymphocyte ratio (NLR) has recently emerged from among inflammatory parameters as a potential indicator of vascular complications and poorer outcome in patients with diabetes. This study aimed to evaluate: 1) the impact of diabetes on NLR; and 2) the role of NLR on the extent of CAD among diabetic patients undergoing coronary angiography. Methods. - Consecutive patients undergoing coronary angiography were included. Diabetic status and main chemistry parameters were assessed at the time of admission. Significant CAD was defined as at least one vessel with stenosis >50%, while severe CAD was left main and/or three-vessel disease, as evaluated by quantitative coronary angiography (QCA). Results. - Diabetes was observed in 1377 of 3756 patients (36.7%); they were older, and displayed higher-risk cardiovascular profile and more complex CAD. Diabetic status was also associated with a significant increase in NLR (P = 0.004). Among diabetics, higher NLR tertile values were related to ageing (P < 0.001), dyslipidaemia (P < 0.001), renal failure (P < 0.001), body mass index (P < 0.001), previous percutaneous coronary revascularization (P = 0.004) and cerebrovascular events (P = 0.003), acute presentation (P < 0.001), treatment at admission with betablockers/statins/ASA (all P < 0.001), diuretics (P = 0.01) or clopidogrel (P = 0.04), platelet count (P = 0.03), white blood cell count, creatinine, glycaemia and C-reactive protein (P < 0.001), and inversely related to haemoglobin, triglyceride levels (P < 0.001) and smoking (P = 0.03). NLR was associated with multivessel disease (P < 0.001), degree of stenosis (P = 0.01), type Clesions (P = 0.02), coronary calcifications and intracoronary thrombus (P < 0.001), but inversely with in-stent restenosis (P = 0.003) and TIMI flow grade (P = 0.02). Also, NLR was directly related to CAD prevalence (P < 0.001; adjusted OR [95% CI]: 1.62 [1.27-2.07], P < 0.001) and CAD severity (P < 0.001; adjusted OR [95% CI]: 1.19 [1.00-1.43], P = 0.05). Conclusion. - NLR is increased among diabetic patients and, in such patients, is independently associated with the prevalence and severity of CAD. Further studies are now needed to confirm present results and to evaluate the underlying pathophysiological mechanisms behind our findings.