Background The precise physiopathological association between the courses of neurodegeneration and cognitive decline in type 2 diabetes mellitus (T2DM) remains unclear. This study sought to comprehensively investigate the distribution characteristics of gray matter atrophy in middle-aged T2DM patients with newly diagnosed mild cognitive impairment (MCI). Methods Four groups, including 28 patients with early-onset MCI, 28 patients with T2DM, 28 T2DM patients with early-onset MCI (T2DM-MCI), and 28 age-, sex-, and education-matched healthy controls underwent three-dimensional high-resolution structural magnetic resonance imaging. Cortical and subcortical gray matter volumes were calculated, and a structural covariance method was used to evaluate the morphological relationships within the default mode network (DMN). Results Overlapped and unique cortical/subcortical gray matter atrophy was found in patients with MCI, T2DM and T2DM-MCI in our study, and patients with T2DM-MCI showed lower volumes in several areas than patients with MCI or T2DM. Volume loss in subcortical areas (including the thalamus, putamen, and hippocampus), but not in cortical areas, was related to cognitive impairment in patients with MCI and T2DM-MCI. No associations between biochemical measurements and volumetric reductions were found. Furthermore, patients with MCI and those with T2DM-MCI showed disrupted structural connectivity within the DMN. Conclusion These findings provide further evidence that T2DM may exacerbate atrophy of specific gray matter regions, which may be primarily associated with MCI. Impairments in gray matter volume related to T2DM or MCI are independent of cardiovascular risk factors, and subcortical atrophy may play a more pivotal role in cognitive impairment than cortical alterations in patients with MCI and T2DM-MCI. The enhanced structural connectivity within the DMN in patients with T2DM-MCI may suggest a compensatory mechanism for the chronic neurodegeneration.

中文翻译：

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2 型糖尿病可能会加剧早发性轻度认知障碍患者的灰质萎缩

背景 在 2 型糖尿病 (T2DM) 中，神经变性病程与认知能力下降之间的确切病理生理学关联仍不清楚。本研究旨在全面调查新诊断为轻度认知障碍（MCI）的中年T2DM患者灰质萎缩的分布特征。方法 4 组，包括 28 例早发性 MCI 患者、28 例 T2DM 患者、28 例 T2DM 早发性 MCI（T2DM-MCI）患者和 28 名年龄、性别和教育匹配的健康对照高分辨率结构磁共振成像。计算皮质和皮质下灰质体积，并使用结构协方差方法评估默认模式网络（DMN）内的形态关系。结果在我们的研究中，在 MCI、T2DM 和 T2DM-MCI 患者中发现了重叠和独特的皮质/皮质下灰质萎缩，并且 T2DM-MCI 患者在多个区域的体积低于 MCI 或 T2DM 患者。皮层下区域（包括丘脑、壳核和海马）的体积减少与 MCI 和 T2DM-MCI 患者的认知障碍有关，但在皮层区域没有。未发现生化测量与体积减少之间的关联。此外，患有 MCI 的患者和患有 T2DM-MCI 的患者在 DMN 内显示出结构连接性中断。结论 这些发现提供了进一步的证据，表明 T2DM 可能会加剧特定灰质区域的萎缩，这可能主要与 MCI 相关。与 T2DM 或 MCI 相关的灰质体积受损与心血管危险因素无关，在 MCI 和 T2DM-MCI 患者中，皮质下萎缩可能比皮质改变在认知障碍中发挥更关键的作用。T2DM-MCI 患者 DMN 内增强的结构连接可能提示慢性神经退行性变的代偿机制。