〔Abstract〕 Objective To investigate morphological and functional neural network alterations in the primary visual cortex (V1) during early-stage diabetes. Methods 32 SPF male C57BL/6J mice were randomly divided into control and diabetic groups. Type 1 diabetes was induced by intraperitoneal streptozotocin (STZ) injection, with model validation via oral glucose tolerance test (OGTT) at week 4. Nissl staining was used for structural analysis. Immunohistochemistry was used for assessing CaMKII and SST expression, and SST signal density on CaMKII⁺ neurons in V1. In vivo electrophysiology was used for studying neuronal firing and functional connectivity. Results Compared with the control mice, nissl staining showed diabetic mice exhibited significant V1 thinning (P=0.02), reduced neuronal density (P=0.01); immunohistochemistry found decreased SST integral optical density (P=0.02) and elevated mean fluorescence intensity (P=0.0l), and lower SST density on CaMKⅡ+ neurons; In vivo electrophysiology studies indicated reduced action potential peak-to-trough ratio and the absolute values of slope (P<0.01), as well as impaired functional connectivity, including conditionalfiring, mutualinformation, and Granger causality (P<0.000 1). Conclusion Early diabetes induces V1 structural atrophy accompanied by SSTergic system disruption and multi-level functional degradation from single neurons to neural networks.