INS and Alzheimer disease: The pathogenesis of AD generally involves Aβ plaque‐related neurodegeneration [3], neurofibrillary tangle formation [4], synaptic dysfunction, neurotransmitter imbalance [5], neuroinflammation [6], gut microbiota changes [7], genetic mutations [8], oxidative stress [9], autophagy [10], insulin resistance [11], etc. In recent years, the discovery of the microbiota–gut–brain axis (MGBA) has provided new ideas for studying the mechanism underlying AD pathogenesis [12].