| Objective: The detection of urinary albumin is a sensitive and reliable method for early diagnosis of diabetic nephropathy. In the patients with diabetes, the appearance of microalbuminuria(MAU) not only indicates the damage to the kidney glomerular, but also is a sign of the dysfunction of the whole systemic vascular endothelial dysfunction. Using proton magnetic resonance spectroscopy(1H-MRS) is a non-invasive in vivo nerve and biochemical analysis technology, through the dynamic observation and quantitative analysis of metabolite concentrations reflect the metabolism of the brain tissue local abnormal changes before in conventional imaging studies appear obvious abnormal change. 1H-MRS was an important value to found abnormalities of the brain change. This study using 1H-MRS to detected the cerebral metabolic changes in patients with type 2 diabetes mellitus(T2DM). To investigate the association of the microalbuminuria(MAU) and N-acetyl aspartic acid(NAA), myo-inositol(MI) and choline compounds(Cho) levels of frontal cortex and semi oval center region in T2 DM patients, and speculated the pathophysiological mechanism.Methods: There were no abnormal changes in the structure of the brain tissue in all cases after magnetic resonance imaging. We obtained the general clinical data by the questionnaire and venous hematology detection. 10 hours urine samples were collected and urine albumin was determined by radioimmunoassay. A total of 61 type 2 diabetes mellitus patients were divided into two groups based on the urinary albumin excretion ratio(UAER), the normal microalbuminuria group(DM group, UAER<20μg/minute, n=29) and microalbuminuria group(DA group, UAER≥20μg/min, <200μg /min, n=32). Twenty health controls(HC group) were also involved in this study. We used 1H-MRS to evaluate the changes of brain metabolites for type 2 diabetes mellitus patients. Voxels were placed in the cortex of frontal and semi oval center area. Creatine(Cr) as internal reference values, calculated the NAA/Cr, Cho/Cr and MI/Cr ratio.Results: Age, gender, blood pressure, BMI, blood lipid, urea nitrogen, and creatinine had no obvious difference among three groups. The FPG, PPG, Hb A1 c level of the DA group and DM group were significantly higher than that of HC group. The levels of UAER in DA group were higher than those in DM group and HC group. There were significant differences in the duration of diabetes between DA and DM groups. In the cortex of frontal area: NAA/Cr ratios of the DA group were significantly lower than those in the DM and HC group, NAA/Cr ratios in the DM group were significantly lower than those in the HC group; Cho/Cr ratios were no significantly increased in the three groups; DA group MI/Cr ratios were increased compared with the HC group. In the semi oval center area: NAA/Cr ratios of the DA group were significantly lower than those in the HC group; DM group Cho/Cr ratios were increased compared with the HC group, the Cho/Cr ratios of DA group was slightly lower than DM group, but no statistical significance; MI/Cr ratios were significantly higher in the DA group compared with those in the DM group and HC group, MI/Cr ratios of the DM group and HC group were no statistically significant difference. NAA/Cr ratios of the DA group in the cortex of frontal were negatively correlated with the level of UAER(r=-0.768, P=0.026).Conclusion: The levels of NAA in related brain tissue associated with T2 DM patients were lower than those of healthy people, and the levels of Cho and MI levels were higher than those of healthy population, which indicated that abnormal metabolism of brain tissue was changed. Data analysis results suggest that with MAU appeared the brain tissue metabolic abnormalities are more evident and central nervous system damage is more serious in patients with type 2 diabetes, it may due to the combined with glomerular lesions patients the glucose metabolism disorder last longer, individual susceptibility factors more sensitive and vascular endothelial permeability increased significantly. At the same time, the external toxins through the impaired endothelial cells lead to the functional disorder of neurons. Data showed that the frontal cortex NAA / Cr ratios decreased obviously, while in semi oval center regional MI/ Cr ratios increased more significantly of the patients with T2 DM in this study, it may be related to study population and the different organization structure in regions of the select brain tissue region. The pathological and physiological changes considered to the neuronal function decreased, apoptosis, degradation of the cell membrane, increase of the number of nerve fibers and the number of glial cells due to high blood glucose or inflammatory stimuli. |
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