Body composition and carbohydrate and lipid metabolism were examined in seventeen patients with myotonic dystrophy (MD). Body cell mass and body fat were determined with isotope dilution methods. Adipose tissue fat cell weight was measured and total fat cell number of the body could be estimated. Fasting concentrations of blood glucose, plasma triglyceride, cholesterol, and insulin as well as of glucose and insulin after ingestion of 100 gm. of glucose were also determined.
In comparison with pertinent controls, MD patients showed no difference in body weight, although body composition was markedly altered with decreased body cell mass and increased body fat mass. Patients without physical impairment showed no derangements, of metabolism. However, disabled MD patients with pronounced decrease of body cell mass had decreased glucose tolerance and increased levels of fasting plasma insulin and lipids. It was concluded that deranged lipid or carbohydrate metabolism is not a primary characteristic of MD but a phenomenon secondary to muscular impairment and atrophy. Intact muscle function is probably important in regulation of lipid and carbohydrate metabolism.
