Interactive effect of acute and chronic glycemic indexes for severity in acute ischemic stroke patients

BACKGROUND: Diabetes mellitus is a well-established risk factor for ischemic stroke and is known to increase stroke risk by 2–6 fold. Numerous studies have reported the relationship between parameters for glycemic status and stroke-related outcomes; however, studies focusing on the interaction between acute and chronic glycemic status indexes with stroke phenotype are lacking. METHODS: Acute ischemic stroke patients who were admitted to a tertiary hospital stroke center from 2002 to 2015 were consecutively enrolled in this study. Fasting blood sugar (FBS) and serum glycated hemoglobin (HbA1c) levels were recorded as acute and chronic glycemic indexes, respectively. The associations between initial stroke severity and both glycemic indexes were evaluated with consideration of the interaction between the glycemic indexes. Moreover, the distinct effects of stroke subtypes were evaluated. RESULTS: A total of 2595 patients were included in the final analysis. After adjustment for covariates, FBS was associated with initial stroke severity (P < 0.001), while HbA1c was not (P = 0.16). However, an interaction between FBS and HbA1c in association with initial stroke severity was observed (P < 0.001). The association between FBS and initial stroke severity was stronger, with a relatively normal HbA1c level. Among stroke subtypes, the interactions were significant for the large artery disease and cardioembolism subtypes (all, P < 0.001), but for the small vessel occlusion subtype (P = 0.63). CONCLUSIONS: This study shows that HbA1c is an effect modifier for the association between FBS and initial stroke severity, and the interactive effect differs among stroke subtypes. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12883-018-1109-1) contains supplementary material, which is available to authorized users.