Mediation of Systemic Inflammation on Insulin Resistance and Prognosis of Nondiabetic Patients With Ischemic Stroke

Background: Insulin resistance is associated with stroke recurrence and poor functional outcomes of nondiabetic patients with ischemic stroke. The study aimed to investigate whether the association between insulin resistance and the prognosis of nondiabetic patients with ischemic stroke was mediated by systematic inflammation. Methods: Patients with ischemic stroke but without a history of diabetes who were enrolled in CNSR-III (Third China National Stroke Registry) were included in the study and followed up for 1 year after stroke onset. Insulin resistance was determined by using the homeostasis model assessment for insulin resistance (HOMA-IR) method. hs-CRP (high-sensitivity C-reactive protein) and Lp-PLA 2 (lipoprotein-associated phospholipase A 2 ) activity were measured at baseline. The primary outcome was stroke recurrence, and other outcomes included composite vascular events, mortality, and poor functional outcome (modified Rankin Scale score, 3–6). Multivariable Cox or logistic regression analyses were performed to estimate the association between HOMA-IR and the study outcomes. A mediation analysis was performed to examine the relationship between insulin resistance and the study outcomes mediated by systemic inflammation. Results: Among a total of 3808 nondiabetic patients with ischemic stroke who were included in the study, the median HOMA-IR was 1.79 (interquartile range, 1.05–2.97). After adjustments for potential confounders, higher HOMA-IR quartiles were associated with higher risks of stroke recurrence, ischemic stroke, and composite vascular events, especially in the large artery atherosclerosis subtype. hs-CRP partially mediated the association between the HOMA-IR index and the prognosis of ischemic stroke (mediation proportion, 5.9% for stroke recurrence and 7.5% for composite vascular events). No evidence of Lp-PLA 2 activity mediating the association of insulin resistance with stroke outcomes was observed. Conclusions: Our study found that insulin resistance was associated with poor clinical outcomes in nondiabetic patients with ischemic stroke, which was partially mediated by hs-CRP with a modest amount.