Altered static and dynamic intrinsic brain activity patterns in type 2 diabetic patients

Type 2 diabetes mellitus (T2DM) is a metabolic disorder characterized by chronic hyperglycemia resulting from insulin secretion and/or resistance. This study investigated intrinsic brain activity alterations using static and dynamic resting-state fMRI metrics in 65 T2DM patients versus 60 healthy controls. We analyzed fractional amplitude of low-frequency fluctuations (fALFF), dynamic fALFF (dfALFF) and dynamic functional stability(DFS). The T2DM group exhibited increased fALFF in the left inferior temporal gyrus and left fusiform gyrus and decreased fALFF in the bilateral precuneus, medial superior frontal gyrus, left inferior parietal lobule, and right supramarginal gyrus when compared with health controls. The T2DM group also showed increased dfALFF in the bilateral precuneus, left inferior parietal lobule, and right middle frontal gyrus. Moreover, the T2DM group exhibited decreased DFS in the bilateral precuneus, supramarginal gyrus, and left middle frontal gyrus, while the left cuneus showed increased dynamic stability. In the T2DM group, montreal cognitive assessment (MoCA) scores correlated negatively with glycated hemoglobin A_1c (HbA_1c) and fasting blood glucose (FBG), and positively with right supramarginal gyrus acticity in both fALFF and DFS difference regions, Multiple brain regions exhibiting fALFF and DFS alterations showed negative correlations with fasting blood glucose and total cholesterol. These findings indicate that T2DM brain activity demonstrates a distinctive "low-intensity, highly-fluctuating, and destabilized" pattern, suggesting complex neural network dysfunction beyond simple functional suppression.