Sustained Elevation in Monocyte Levels in Diabetic Patients after Infra- Inguinal Revascularization

Context: Diabetes and atherosclerosis are both pro-inflammatory states that may lead to elevations in monocyte levels. It was previously demonstrated that there is a reduction in monocyte levels after infra-inguinal bypass in patients with critical limb ischemia (CLI). We hypothesized that patients with diabetes would not realize the same reduction in monocyte levels post-bypass as patients without diabetes. Objective: To determine whether patients with diabetes would have a sustained sub-clinical inflammation after resolution of CLI with infra-inguinal bypass, as marked by a persistent elevation of monocyte levels. Design: Patients undergoing lower extremity vascular bypass surgery between 2003 and 2013 at the Syracuse VA Medical Center were retrospectively reviewed. Pre- and post-operative leukocyte count with differential were recorded for each patient and stratified according to the presence of diabetes. Results: Patients with CLI and no bypass failure (n=43) were included for analysis of the primary outcome, change in monocyte level. Diabetic (DM+) patients (n=27) and non-diabetic (DM-) patients (n=16) had similar pre-operative leukocyte counts and differential (p>0.05). In DM-, there was a 5.6% decrease in monocyte count post-operatively, whereas there was an elevation in monocytes in DM+ (+20.8%; p<0.05). The overall rate of complications was significantly greater and the time to develop complications significantly less in DM+ (p<0.05). Conclusion: Diabetic patients have a persistent elevation in monocyte levels even after infra-inguinal vascular bypass as compared with non-diabetic patients. This suggests diabetic patients have persistent sub-clinical inflammation even upon resolution of critical limb ischemia.