Thresholds of risk factors for ischemic stroke in type 2 diabetic patients with and without albuminuria—A non-linear approach

Objectives Multiple risk factors in type 2 diabetes may explain their high risk for ischemic stroke (IS). However, it remains unknown whether these risk factors exhibit threshold characteristics and whether these relationships are influenced by albuminuria. The study aims to investigate whether risk factors exhibit any albuminuria specific threshold for IS. Patients and methods This is a prospective cohort study with 6969 Chinese type 2 diabetic patients without history of stroke after a median follow-up of 5.36 years. We identified thresholds of risk factors for IS using hazard ratio plots followed by confirmation using traditional Cox regression analysis. Results In the non-albuminuric group (n = 4008), IS risk started to increase rapidly at a body mass index threshold of 24 kg/m2. The risk of IS declined with increasing blood hemoglobin reaching a threshold value of 14 g/dl. Using these threshold values as cutoff point, body mass index ≥24 kg/m2 and hemoglobin <14 g/dl were associated with 2-fold increased risk of IS in these subjects. In the albuminuric group (n = 2961). IS risk started to increase rapidly from a systolic blood pressure threshold of 135 mmHg and declined with increasing estimated glomerular filtration rate (eGFR) reaching a trough of 115 ml/min per 1.73 m2. Using these values as cutoff points, patients with systolic blood pressure ≥135 mmHg and eGFR <115 ml/min per 1.73 m2 had 2-fold increased risk of IS. Conclusion In type 2 diabetic patients, body mass index, hemoglobin, systolic blood pressure and eGFR exhibit different risk relationships and thresholds for IS contingent upon presence or absence of albuminuria.