Glycogen Storage Disease Program & Disorders of Hypoglycemia

What is Glycogen Storage Disease?

Glycogen Storage Disease (GSD) is a group of rare genetic disorders caused by enzyme deficiencies. GSD is generally divided into liver and muscle types. 

The liver types of glycogen storage diseases that cause Hypoglycemia (low blood glucose/sugar) are 0, Ia, Ib, III, VI, IX, and XI. These are rare disorders, the most common of which effects one out of every 100,000 people. As endocrinologists, our expertise in GSD is restricted to management of these liver/low blood glucose forms.

A healthy liver stores glucose from food in the form of glycogen for our body’s future energy needs. Outside of the times when a person is eating they require a constant source of energy, and that is when the liver is intended to provide glucose to the body. When a constant source of energy is not provided to individuals affected by GSD, the abnormality in their liver causes it to fail in the storage or breakdown of glycogen. This causes the body’s blood glucose levels to drop dangerously low, which leads to severe hypoglycemia, seizures, coma, and potentially death.

Individuals with GSD are at high risk for other health conditions related to the body compensating for the liver’s dysfunction by finding alternative energy sources.

Disorders of Hypoglycemia

Disorders of hypoglycemia (low blood glucose/sugar) are rare. They are most frequently diagnosed in infancy or in early childhood. Underlying causes of disorders of hypoglycemia are numerous and can be difficult to diagnose. Medical science is currently unable to identify an underlying cause for a significant proportion of children presenting with hypoglycemia, and they frequently are given a diagnosis of idiopathic ketotic hypoglycemia. 

For some children with idiopathic ketotic hypoglycemia, it will be identified that they are likely to have a “physiologic” form that is exacerbated by illness or decreased intake at a young age. This form is frequently outgrown when a child reaches school age (5-6 years old), but management is required to minimize risks. For some children with hypoglycemia, hypoglycemia will continue despite dietary adjustments and additional testing and management is needed. This, more recently, is referred to as “pathologic” idiopathic ketotic hypoglycemia. Underlying illness, genetic disorders or medications can be identified as the cause of hypoglycemia in some individuals.