Biomarkers for cognitive decline in patients with diabetes mellitus: evidence from clinical studies

// Xue Zhao 1, * , Qing Han 2, * , You Lv 1 , Lin Sun 1 , Xiaokun Gang 1 and Guixia Wang 1 1 Department of Endocrinology and Metabolism, The First Hospital of Jilin University, Changchun, 130021, Jilin Province, China 2 Hospital of Orthopedics, The Second Hospital of Jilin University, Changchun, 130021, Jilin Province, China * These authors contributed equally to this work Correspondence to: Guixia Wang, email: gwang168@jlu.edu.cn Xiaokun Gang, email: insightful@126.com Keywords: diabetes; cognitive decline; diagnosis; biomarkers Received: July 27, 2017      Accepted: October 30, 2017      Published: December 14, 2017 ABSTRACT Diabetes mellitus is considered as an important factor for cognitive decline and dementia in recent years. However, cognitive impairment in diabetic patients is often underestimated and kept undiagnosed, leading to thousands of diabetic patients suffering from worsening memory. Available reviews in this field were limited and not comprehensive enough. Thus, the present review aimed to summarize all available clinical studies on diabetic patients with cognitive decline, and to find valuable biomarkers that might be applied as diagnostic and therapeutic targets of cognitive impairment in diabetes. The biomarkers or risk factors of cognitive decline in diabetic patients could be classified into the following three aspects: serum molecules or relevant complications, functional or metabolic changes by neuroimaging tools, and genetic variants. Specifically, factors related to poor glucose metabolism, insulin resistance, inflammation, comorbid depression, micro-/macrovascular complications, adipokines, neurotrophic molecules and Tau protein presented significant changes in diabetic patients with cognitive decline. Besides, neuroimaging platform could provide more clues on the structural, functional and metabolic changes during the cognitive decline progression of diabetic patients. Genetic factors related to cognitive decline showed inconsistency based on the limited studies. Future studies might apply above biomarkers as diagnostic and treatment targets in a large population, and regulation of these parameters might shed light on a more valuable, sensitive and specific strategy for the diagnosis and treatment of cognitive decline in diabetic patients.