Imaging hypoglycemia’s effects on the human brain

Iatrogenic hypoglycemia causes recurrent morbidity in most type 1 diabetes patients and in many with type 2 diabetes, sometimes proving fatal. It is the critical limiting factor in the glycemic management of diabetes in both the short and long- term by precluding the maintenance of euglycemia throughout the patient’s lifetime with the condition. The ability to measure the effects of hypoglycemia on the human brain must be understood in order to develop appropriate interventions, optimize glycemic control and minimize risk for negative outcomes. The ability to make such measurements was limited for many decades to assaying the behavioral consequences of presumed hypoglycemia-induced neurologic damage. However, with the advent of high quality in vivo neuroimaging techniques (positron emission tomography in the early 1980s, functional magnetic resonance imaging in the early 1990s), we can now measure the effects of hypoglycemia on the brain more directly and objectively. This review discusses how neuroimaging tools can be used to understand the short, intermediate and long-term consequences of hypoglycemia exposure on both brain structure and function in humans.