Glucose Extremes and Cognitive Function: A Review of the Neurological Impacts of Hypoglycemia and Hyperglycemia in Type 1 Diabetes

This article explores the neurological impacts of hypoglycemia and hyperglycemia on cognitive function in type 1 diabetes. It reviews how fluctuating glucose levels disrupt critical brain metabolic pathways, impairing various cognitive processes such as memory, attention, and executive functioning. The authors highlight both the acute and long-term effects of glycemic variability on critical brain regions, including the hippocampus, prefrontal cortex, and occipital lobes. Notably, both hyperglycemia and hypoglycemia contribute to cognitive dysfunction but through different mechanisms. Hypoglycemia induces an energy crisis in the brain, triggering increased oxidative stress and neuronal vulnerability, with repeated episodes leading to cumulative hippocampal and prefrontal damage. Hyperglycemia results in vascular compromise, disrupting cerebral blood flow and leading to various states of neurotransmitter dysregulation, with chronic exposure being associated with structural changes such as reduced gray matter volume. Diabetes technology devices such as continuous glucose monitoring systems may reduce cognitive impairments associated with glucose fluctuations, but their benefits underscore the limitations of A1C alone and the need for metrics that better capture glycemic variability. This review underscores the need to prioritize glucose control to protect cognitive health in patients with type 1 diabetes.