Nutrient metabolic disorders in muscular dystrophy and their countermeasures

Abstract

Muscular dystrophy (MD) is a genetic disease characterized by progressive muscle weakness. Regardless of the disease type of MD, chronically progressive muscle atrophy and motor function decline are important factors related to nutritional and metabolic disorders. Loss of skeletal muscle mass and decreased physical activity affect total energy expenditure. Therefore, in MD, it is necessary to estimate energy requirements by taking into account the intensity of daily life activities according to the stage of disease progression. Furthermore, since a decrease in skeletal muscle mass causes an increase in insulin resistance and the destroyed muscle tissue is replaced with adipose tissue, measures against glycolipid metabolic disorders must also be taken into consideration. Furthermore, in MD, problems related to development and growth, problems related to heart/respiratory dysfunction, and swallowing dysfunction are deeply related to nutritional/metabolic disorders. Among MDs, myotonic dystrophy (DM1) is known to exhibit a specific disorder of glycolipid metabolism, resulting from a combination of factors, primarily insulin resistance based on abnormal splicing of the insulin receptor. Hyperinsulinemia is observed in 70% of patients, although it is estimated that the incidence of diabetes mellitus with DM1 in Japan is about 20% based on the Neuromuscular Patient Registry (Remudy) data survey. Studies using continues glucose monitoring have pointed out that there are many cases in which hypoglycemia occurs on a daily basis even without any subjective symptoms. Additionally, lipid abnormalities and liver dysfunction are often complicated in DM1. Glycolipid metabolic disorders and liver dysfunction are closely related, so sufficient caution should be taken. Metabolic disorders are complications that could be treated with current knowledge and technology. Nutritional therapy is one of the important modifying treatments in MD.