Scientists discover that high blood sugar can cause muscle atrophy

Diabetes, a condition that one in four Americans have, is a leading cause of death and disability. While it’s linked to multiple health problems, chief of which are cardiovascular disease and multiple organ damage, Japanese researchers found that it can also cause a rapid decline in muscle mass. In a study published in JCI Insight, researchers from the Kobe University Graduate School of Medicine revealed that high blood sugar levels (hyperglycemia) can lead to muscle atrophy via the upregulation of a certain protein.

The role of diabetes in muscle loss

The loss of muscle mass, also known as sarcopenia, is a condition that’s usually seen in people over the age of 50. Older adults with sarcopenia lose, on average, three percent of their muscle strength every year, impairing their physical mobility. The condition also makes them prone to many health problems, which can ultimately shorten their life expectancy. These consequences make sarcopenia a serious health burden in regions where there are many older adults.

Currently, one in 11 people around the world is 65 years old or older, according to the latest World Population Prospects report. By 2050, these numbers are expected to balloon to one in six people. Regions such as Europe and North America are expected to have at least a quarter of their populations be older adults. Countries such as Germany, Italy, and Japan – where the study was conducted – are also estimated to see a decline in their populations within 10 years.

In the study, researchers noted that while muscle loss is a complication that many older adults with diabetes face, the link between the two conditions is ambiguous. They proffered that insulin may have a role to play in sarcopenia: Given its role in cell growth and development, having insufficient amounts of insulin may lead to suppressed cell growth and contribute to a decline in muscle mass.

To test their hypothesis, the team treated mice with streptozotocin, which caused high blood sugar levels (hyperglycemia) and low blood insulin levels (hypoinsulinemia). The team found that mice treated with streptozotocin had a marked loss of muscle mass 21 days after diabetes induction. This indicated that sarcopenia isn’t caused by an increase in catabolism or the breakdown of large molecules into smaller units, but by diabetes. They also discovered that in diabetic mice, KLF15 expression was upregulated. KLF15 is a protein linked to muscle atrophy.

Under normal conditions, KLF15 is rapidly degraded, thanks to another protein called WWP1. When WWP1 attaches a small protein called ubiquitin to KLF15, it promotes the degradation of KLF15. However, elevated blood sugar levels decrease WWP1 expression, leading to a rise in KLF15 levels in skeletal muscles.

“We have shown that hyperglycemia, a central disorder in diabetes, promotes skeletal muscle atrophy via a WWP1/KLF15 pathway,” the