Clinical Characteristics for the Relationship between Type-2 Diabetes Mellitus and Cognitive Impairment: A Cross-Sectional Study

Abstract

ABSTRACT:We explored the potential differences in cognitive status, lipid and glucose metabolism, ApoEε4 alleles and imaging between diabetic and non-diabetic subjects. 83 subjects with normal cognitive function and 114 mild cognitive impaired patients were divided into four groups by history of diabetes. General demographics was collected from all participants followed by MRI scan, biochemical examinations and a series of neuropsychological tests. Student's t test, multiple regressions and one-way ANOVA were applied to investigate the differences between groups. Comparing diabetic patients with non-diabetic subjects in the mild cognitive impaired group, we found several decreased items in recall of three words in MMSE (p=0.020), AVLT and SCWT (p＜0.050). The multiple linear regression revealed that two-hour glucose level (B= -0.255，p＜0.001) and fasting C-peptide (B= -0.466， p=0.001) had negative effects on the score of MMSE. In addition, diabetic patients treated with insulin and other diabetes medication performed better in part of the AVLT (p＜0.050) compared to patients with insulin treatment or oral antidiabetic medication only. Patients with metformin medication had a better memory outcome compared to patients with sulphonylurea medication in the AVLT long delay free recall (p =0.010). These findings show that patients of mild cognitive impairment with diabetes mellitus have a worse outcome in attention, information processing speed and memory compared to non-diabetic patients. Higher two-hour glucose level and C-peptide level may be risk factors for severe cognitive impairment in type-2 diabetes mellitus patients. The results of this study also suggest that medication may have effects on cognitive function.Key words: Type-2 diabetes mellitus, mild cognitive impairment, C-peptide, blood glucoseThe incidence of type-2 diabetes mellitus (T2DM) in China has dramatically increased in the last decade. Besides the well-known connection between T2DM and peripheral nervous system disease, the diabetes-induced lesions in the central nervous system (CNS), such as cerebrovascular disease and cognitive dysfunction, are receiving increased attention. Several epidemiological studies have found that T2DM is an independent risk factor for both Alzheimer's disease (AD) and vascular dementia (VaD) [1,2]. In addition, further research has shown that T2DM may also exercise influence on the prevalence of mild cognitive impairment (MCI), which is considered a pre-clinical stage of dementia. In Luchsinger and colleagues' study [3], the results indicated that diabetes mellitus is related to a relatively higher risk for all causes of MCI (about 1.5 fold). In another recent metaanalysis report, diabetes was shown to have higher risk for any dementia and MCI (1.46 for AD, 2.48 for VaD and 1.21 for MCI) [4].The present studies have confirmed that T2DM is a robust risk factor for cognitive dysfunction. However, the precise mechanisms remain to be elucidated [5]. A wide range of metabolic and vascular disturbances have been proposed to e...

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