The tendency of the body to react to extremely low blood sugar (hypoglycemia) by overcompensating, resulting in high blood sugar. The Somogyi effect, also known as the “rebound” effect, was named after Michael Somogyi, the researcher who first described it.
When blood glucose levels drop too low, the body sometimes reacts by releasing counterregulatory hormones such as glucagon and epinephrine. These hormones spur the liver to convert its stores of glycogen into glucose, raising blood glucose levels. This can cause a period of high blood sugar following an episode of hypoglycemia.
The Somogyi effect is most likely to occur following an episode of untreated nighttime hypoglycemia, resulting in high blood sugar levels in the morning. People who wake up with high blood sugar may need to test their blood glucose levels in the middle of the night (for example, around 3 AM). If their blood sugar level is falling or low at that time, they should speak with their health-care team about increasing their food intake or lowering their insulin dose in the evening. The only way to prevent the Somogyi effect is to avoid developing hypoglycemia in the first place.