According to a study published in PLoS One which was conducted on diabetic rodents, a cellular protein that may prevent nerve cell death also helps improve insulin production and lower blood glucose levels.

The research, which was conducted by scientists both at the Albert Einstein College of Medicine at Yeshiva University and at the University of California Los Angeles, is the first to demonstrate the role of a small peptide, or protein, humanin, in glucose production. They also demonstrated that the peptide closely resembles leptin, another protein. Both act on the brain to influence the metabolism of glucose.

Humanin is located in mitochondria, which are structures within the body that populate the cytoplasm of cells and provide fuel for energy. Researchers not associated with the new study first identified the peptide in 2001 in brain nerve cells and other studies have suggested that it may have a role in protecting nerve cells from death associated with Alzheimer’s disease.

“This new role of humanin in glucose metabolism, in addition to its role in Alzheimer’s disease, is very intriguing since scientists have long proposed a link between type 2 diabetes and Alzheimer’s disease,” says Nir Barzilai, M.D., a co-senior author of the study, the Ingeborg and Ira Leon Rennert Professor of Aging Research, and director of the Institute for Aging Research at Einstein. “Humanin could turn out to be a therapeutic option for two common debilitating diseases that affect millions of people. Additionally, humanin may help treat other age-related diseases.”

During the course of their research Dr Barzilai and his associates introduced humanin into the brains of diabetic rats to determine what effect humamin had on glucose metabolism. The peptide improved insulin sensitivity greatly, in both skeletal muscle and the liver. The researchers also found that a single dose of a high potency form of humanin caused a significant lowering of the blood glucose levels in the rodents.

Says Dr Barzilai, “The improvement in insulin sensitivity caused by centrally administered humanin may be one of the main mechanisms through which humanin regulates cell survival,” This may provide another potential mechanism by which humanin protects against Alzheimer’s disease.”

To investigate the possible link between humanin and both Alzheimer’s disease and type 2 diabetes, which are both normally, considered to be age related conditions the researchers examined the brain strictures of the diabetic rats. They found that humanin levels in two of the brain’s structures (the cortex and the hypothalamus) decreased with age in the rodents, as it also did in the skeletal muscle. A separate investigation by the team found that circulating levels of humanin in the blood of humans decreased with age.

“From these results, we conclude that the decline in humanin with age could help explain why Alzheimer’s disease and type 2 diabetes are more common in older people,” says Dr. Barzilai.