Functional brain connectivity in type 1 diabetes and associations to diabetes complications - a systematic review of fMRI studies.

A systematic review was conducted to investigate functional brain changes in type 1 diabetes mellitus (T1DM) assessed with functional magnetic resonance imaging (fMRI) between 2006 and 2025. A total of 27 eligible studies were included, involving 1072 participants with T1DM, with a mean age ranging from 20.4 to 51.5 years. The quality of these studies was evaluated using the NIH Quality Assessment Tool. Resting-state fMRI (n = 12) demonstrated 1) altered brain networks, especially in the default mode and salience networks, and 2) changes in subcortical regions and the frontal lobe. Task-based fMRI (n = 15) showed increased activity in the visual, salience, and thalamic networks, and decreased activity in the default mode network. The review highlights the complex relationship between T1DM and brain changes, presenting evidence of deviations from normal brain activity in specific areas involved in sensory-motor, limbic and cognitive regions that may reflect neurophysiological adaptations or consequences related to T1DM. Registration: PROSPERO (International Prospective Register of Systematic Reviews) under ID: CRD42023456789.