Metabolic studies in muscular dystrophy: a role for insulin.

Insulin is important in maintaining carbohydrate tolerance and normal muscle mass. Cabohydrate intolerance and muscle wasting are frequent in the neuromuscular disorders associated with endocrinopathy and in myotonic dystrophy. Studies of the systemic factors that regulate insulin release in myotonic dystrophy have shown that excessive insulin release occurs on oral glucose tolerance testing with diminished peripheral effectiveness. Study of the peripheral action of insulin by forearm investigations of myotonic dystrophy patients and disease controls has suggested that the peripheral skeletal muscle insulin receptor may be relatively insensitive im myotonic dystrophy. It is possible that an evaluation of insulin regulation and action in myotonic dystrophy or many neuromuscular disorders may have eventual therapeutic implications. If neuromuscular disorders other than myotonic dystrophy have evidence of peripheral insulin ineffectiveness, reasonable causes could be an excessive level of an antagonistic hormone, a faulty insulin receptor, or inadequate pancreatic insulin release.