Insulin booster restores muscle growth in elderly

WASHINGTON - People tend to link insulin with diabetes, but it has other lesser known uses too. A study has shown that loss of response to insulin plays a major role in decrease of physical strength that occurs as people grow older.

Insulin is necessary for muscle growth, increasing blood flow through muscle tissue, encouraging nutrients to disperse from blood vessels and itself serving as a biochemical signal to boost muscle protein synthesis.

University of Texas Medical Branch - Galveston (UTMB-G) researchers have shown that by increasing insulin levels above the normal range in elderly test subjects, they can restore the impaired muscle-building process responsible for age-related physical weakness.

“Insulin is normally secreted during food intake,” said Elena Volpi, senior study co-author.

“When you give insulin intravenously and increase the blood insulin levels to the same amount produced after a meal, you see that in young people it stimulates protein synthesis and muscle growth, while in older people it really doesn’t.”

“But when we gave seniors double the insulin they would normally produce after eating, their muscles were stimulated like those of young people,” added Volpi, according to an UTMB-G release.

Volpi and her co-authors - postdoctoral fellows Satoshi Fujita and Kyle Timmerman, graduate student Erin Glynn and professor Blake B. Rasmussen - worked with elderly volunteers to examine the response of thigh muscles to the two different blood insulin levels.

All the data pointed in the same direction, showing that a blood insulin level double that produced by a typical meal seems to turn back the clock on elderly thigh muscle.

These findings appeared in the September issue of Diabetologia.