Insulin autoimmune syndrome is a rare condition that causes low blood sugar (hypoglycemia). This occurs because the body begins to make a specific kind of protein called antibodies to attack insulin. Insulin is a naturally occurring hormone that is responsible for keeping blood sugar at a normal level. When blood sugar levels get too high, insulin helps to store the sugar for future use. People affected by insulin autoimmune syndrome have antibodies that attack insulin, causing it to work too hard and the level of blood sugar to become too low. Insulin autoimmune syndrome most often begins during adulthood.

Exactly why these antibodies against insulin are suddenly produced can vary from person to person. In some cases, insulin autoimmune syndrome occurs in a person with another autoimmune disease, which can indicate that the immune system in the body is not behaving correctly. Additionally, a certain class of medications called sulphydryl compounds have been shown to sometimes cause insulin autoimmune syndrome. Some of these medications are used to treat other autoimmune conditions. Recently, a compound called alpha-lipoic acid has been associated with an increased risk of developing insulin autoimmune syndrome. This compound is sometimes used for dieting purposes.