Correlation Of Mild Cognitive Impairment With The Thickness Of Retinal Nerve Fiber Layer And Serum Indicators In Type 2 Diabetic Patients

Background:The cognitive impairment caused by type 2 diabetes mellitus(T2DM)has received much attention in recent years,but there are few studies to identify and diagnose markers of cognitive impairment.The retina and the central nervous system share similar embryonic origins and anatomical and physiological characteristics.Retinal Nerve Fiber Layer(RNFL)thickness can be used as an indicator to assess changes in the central nervous system.In addition,cognitive decline in patients with T2DM is associated with chronic systemic inflammation and the accumulation of advanced glycosylation end products.Current studies suggest that RNFL,Interleukin-18(IL-18),irisin,Carboxymethyl-lysine(CML),receptors for advanced glycosylation end-products(RAGE)and AGE(RAGE)are associated with cognitive function,and the relationship between these indicators and cognitive function in patients with T2DM is unclear..Objectives:The aim of this study was to assess RNFL thickness and the serological levels of interleukin-18(IL-18),irisin,carboxymethyl-lysine(CML),receptors for advanced glycosylation end products(RAGE)in patients with type 2 diabetes,to explore their correlation with cognitive function in T2DM patients and to assess their diagnostic efficacy in the diagnosis of mild cognitive impairment in T2DM patients.Methods:One hundred and eight patients with T2DM were selected from the Department of Endocrinology,Second Hospital of Shandong University,including 60 patients in the T2DM group and 48 patients in the T2DM combined with mild cognitive impairment(MCI)group.Twenty-three volunteers were also recruited as normal controls.The participants had bilateral RNFL thickness measurements using optical correlation tomography line imaging and cognitive assessments using the Mini-Mental State Examination(MMSE)and the Montreal Cognitive assessment(MoCA).The differences in RNFL thickness and serological levels of IL-18,irisin,CML and RAGE were compared between the three groups to analyse their correlation with cognitive function.ROC curves were applied to assess the diagnostic efficacy of specific indicators for MCI.Results:1.The average thickness of RNFL in the right eye was significantly lower in the T2DM group and the T2DM combined with MCI group compared with the normal control group(p<0.05).The average thickness of RNFL in the right eye was significantly thinner in the T2DM combined with MCI group compared with the T2DM group(p<0.05).2.Compared with the normal control group,IL-18,CML,and RAGE levels were significantly higher(p<0.05)and irisin levels were significantly lower(p<0.05)in the T2DM group and the T2DM combined with MCI group.Compared with the T2DM group,IL-18,CML and RAGE levels were significantly higher(p<0.05)and irisin levels were significantly lower(p<0.05)in the T2DM combined with MCI group.3.The average RNFL thickness,irisin,CML,and RAGE were significantly correlated with MoCA and MMSE in the right eye(p<0.05).4.Logistic regression showed that the average RNFL thickness in the right eye was a protective factor for MCI in patients with T2DM,and CML and RAGE were risk factors for MCI.5.The area under the ROC curve for the average RNFL thickness in the right eye,CML,and RAGE to predict MCI in patients with T2DM were 0.853,0.874,and 0.815,respectively.Conclusion1..The average RNFL thickness in the right eye is positively correlated with cognitive function.The serum of CML and RAGE levels are negatively correlated with cognitive function.2.The average RNFL thickness in the right eye,the serum of CML and RAGE have possible diagnostic value in MCI in T2DM patients.