According to a study published in The Journal of Clinical Endocrinology and Metabolism, researchers have found an association between low levels of a specific hormone and increased risk of metabolic disease in humans.

The study was conducted by Andrew Butler from the Florida campus of The Scripps Research Institute in collaboration with Peter J. Havel, professor of molecular biosciences and nutrition at the University of California, Davis.

The researchers focused on the hormone adropin, that had been previously identified by Butler’s laboratory during an analysis of obese and insulin-resistant mice. Adropin is thought to play a vital role in controlling sugar levels and fatty acid metabolism.

Butler explained:

“The results of this clinical study suggest that low levels of adropin may be a factor increasing risk for developing metabolic disorders associated with obesity and insulin resistance, which could then lead to diseases such as type 2 diabetes.”

Around 47 million adults in the U.S have metabolic syndrome, as stated by the American College of Cardiology. The National Institutes of Health defines metabolic syndrome as a group of risk factors, particularly obesity and insulin resistance, that occur alongside one another and increase the risk for developing coronary artery disease, stroke, and type 2 diabetes.

In the new study, which included 85 women and 45 men, the researchers demonstrated that obesity is linked with lower adropin levels. Lower adropin levels were additionally seen in people with a higher “metabolic syndrome risk factor” score, a score based on measuring triglycerides, LDL cholesterol, HDL, glucose, blood pressure, and waist circumference.

In addition, the team found circulating adropin concentrations dramatically increased at 3 and 6 months after gastric bypass surgery in patients who are morbidly obese. Remarkably, adropin levels reverted back to pre-surgical levels at 12 months after surgery.

Furthermore, the researchers found that in patients of normal weight, women had lower plasma adropin levels than men. Additionally, obesity had a greater adverse effect on adropin levels in men. According to the researchers, obesity in woman was also not connected with lower plasma adropin levels. The significance of the differences between men and woman is currently unknown.

Butler explained: “But the link between low levels of adropin and increased metabolic risk was observed in both sexes. The impact is there, irrespective of gender.”

The team also discovered that adropin levels generally with age – the decline was greatest in people over Thirty years of age. Just like obesity, the aging effect seemed to be more evident in men.

The latest study is a crucial extension of previous pre-clinical studies using animal models published in the July edition of Obesity. In that study, the researchers removed the gene encoding adropin from mice and discovered that, while normal in appearance, adropin-deficient mice have insulin resistance and, when raised on high-fat diets, develop a more serious impaired glucose tolerance (IGT). These findings indicate decreased insulin production and attenuated response to insulin, which are the characterizing features of type 2 diabetes.

Furthermore, mice having just one single working copy of the gene encoding adropin also showed increased propensity for developing impaired glucose tolerance with obesity. According to the researchers, results from the trial provided essential pre-clinical evidence that low levels of adropin are linked to greater risk of developing type 2 diabetes.

In other studies, the team found that obese mice show significant reductions in circulating adropin levels, and that insulin resistance was reversed after injections with a synthetic form of atropin.

Butler said:

“The data from these studies provide strong evidence suggesting that low levels of adropin may be an indicator of risk for insulin resistance in obesity and, consequently, an increased risk for metabolic diseases, including type 2 diabetes. We see a lot of similarity between animal model data and the new human data-low adropin levels in humans are associated with a host of metabolic syndrome risk factors normally associated with obesity and insulin resistance.”

Combined, these studies indicate the possibility that therapeutics created to increase the supply of adropin could be beneficial in combating obesity and metabolic disease.

Written by Grace Rattue