Glycogen storage disease type 1 and diabetes: learning by comparing and contrasting the two disorders

Glycogen storage disease type 1 (GSD1) and diabetes may look at first like totally opposite disorders, as diabetes is characterized by uncontrolled hyperglycaemia, whereas GSD1 is characterized by severe fasting hypoglycaemia. Diabetes is due to a failure to suppress endogenous glucose production (EGP) in the postprandial state because of either a lack of insulin or insulin resistance. In contrast, GSD1 is characterized by a lack of EGP. However, both diseases share remarkably similar patterns in terms of pathophysiology such as the long-term progression of renal dysfunction and hepatic steatosis leading to renal failure and the development of hepatic tumours, respectively. Thus, much may be learned from considering the similarities between GSD1 and diabetes, especially in the metabolic pathways underlying nephropathy and fatty liver, and perhaps even more from their differences. In this review, the differences between diabetes and GSD1 are first highlighted, as both are characterized by alterations in EGP. The molecular pathways involved in liver pathologies, including steatosis, hepatomegaly (glycogenic hepatopathy) and the development of liver tumours are also compared. These pathologies are mainly due to the accumulation of lipids and/or glycogen in hepatocytes. Finally, the similar pathways leading to nephropathy in both diabetic and GSD1 patients are described. In conclusion, comparisons of these pathologies should lead to a better understanding of the crucial role of EGP in the control of glucose and energy homoeostasis. Moreover, it may highlight similar therapeutic targets for the two disorders. Thus, this review suggests that the treatment of adult patients with either GSD1 or diabetes could be carried out by the same specialists-diabetologists.