Nonlinear association between glycated hemoglobin levels and mortality in elderly patients with non-diabetic chronic kidney disease: a national health and nutrition examination survey analysis - Huang, Lihua; He, Liuliu; Zeng, Qingfeng; Huang, Jinjing; Luo, Xiaoyan; Zhong, Qiuming (Frontiers in Endocrinology, 2025)