Hypoglycemic episodes occur commonly in patients with insulin-dependent (Type I) diabetes and are associated with several negative sequelae. These include unpleasant symptoms, deterioration in cognitive-motor functions, embarrassment, accidents, unconsciousness, seizures, and even death. Although hypoglycemic disruptions in cognitive and motor function caused by neuroglycopenia are well-documented, the effects of hypoglycemia on other areas of psychosocial function have received less scientific attention. This paper examines the impact of hypoglycemia on emotional status, social behavior, and relationships. The physical symptoms and cognitive impairment that occur with hypoglycemia are caused primarily by hormonal changes and neuroglycopenia. These physiologic responses also seem to cause negative changes in affect and social behavior. These include changes in acute mood state, such as feelings of tension and anger, as well as negative interpersonal behavior, such as argumentiveness. Patients may also develop significant fear of hypoglycemia (FOH) and engage in behaviors aimed at avoiding low blood glucose levels, which may jeopardize metabolic control. Nondiabetic family members, who witness episodes and often must provide emergency treatment, can experience significant distress. Parents of diabetic children who have experienced unconsciousness exhibit high FOH, as do spouses of diabetic adults who have frequent episodes. Taken together, the research clearly shows that hypoglycemia can have a significant negative impact on psychosocial function and quality of life, which has important clinical and empirical implications.