Epigenetic Marks Found In Blood Test Could Help Save Diabetics

Type 2 diabetes is a chronic illness in which a person’s body cannot produce enough insulin to process blood sugar in a healthy way. It affects millions of people all over the world, and it can be a debilitating and even deadly disease if not properly managed.

The inability to metabolize glucose can lead to long-term damage to blood vessels in organs and tissues— and may eventually lead to death. Quantifying this damage lets people take action, changing their habits and motivating changes in behaviors like diet and exercise.

Usually, such measurements form an expensive, time-consuming regimen of office visits and myriad exams, imaging studies like ultrasounds and various blood tests. This places a huge burden on patients, caregivers, and the medical system as a whole.

What if this could all be replaced with one simple blood test?

Such a test could even be carried out at any clinic or diagnostic center where other blood is already drawn. Researchers are furiously working on finding an answer to this problem, particularly for some of the most common diseases that affect massive portions of the population.

A recent collaboration between researchers at the Zhongnan Hospital of Wuhan University in China, The University of Chicago, and Northwestern University sought to identify epigenetic changes that correlated with outcomes in patients with type 2 diabetes. Such changes could then be detected using a noninvasive test—like a blood draw. 

Using chemical labeling that selectively tagged for 5-hydroxymethylcytosine (5-hmC-Seal) in genomes, these researchers looked at a collection of sixty-two patients. The findings led to a statistically significant difference in 5-hmC markers that directly correlated with microvascular and macrovascular complications in these patients. We’ve previously seen diabetes studies involving DNA methylation levels in the blood, but none specifically measuring 5-hmC.

“We reasoned that . . .  there could be damage to the tissue, damage to the cells, that would release free circulating DNA,” said Wei Zhang, co-author on the study and geneticist/epidemiologist at the Feinberg School of Medicine at Northwestern University.

Dr. Zhang continues: “This study proves that our technology is so sensitive that it can be used not only in cancer . . . but also in chronic diseases such as diabetes.” The fact that this was evident in circulating DNA—not just in fixed tissue samples, but in DNA that is floating and traveling through the body—is a breakthrough, because it allows for a blood sample to be drawn and analyzed in a meaningful way. This contrasts with existing methods which may be unreliable or focused heavily on local tissue.

The correction to vascular changes is important as well. Vascular changes are potential indicators of health outcomes because they directly affect everything from the insulin resistance to the inflammation that people with type 2 diabetes experience. Although this study is a pilot study, with a relatively limited size of samples at sixty-two patients, it was enough to pick up on a trend that warrants further investigation.

Some scientists, although excited about the findings, are still a bit reserved about the conclusions drawn. “I thought it was novel,” remarks Phillip Marsden, an M.D./Ph.D. at the University of Toronto, and a researcher in cardiovascular illness and epigenetics. “I hadn’t been aware they could do hydroxymethylation screens of circulating free DNA.” Much further validation will be needed, including repeating these findings across a much larger sample size.

Source: Y. Yang et al. (2019). 5-Hydroxymethylcytosines in Circulating Cell-Free DNA Reveal Vascular Complications of Type 2 Diabetes.Clinical Chemistry 65(11)

Reference: Katarina Zimmer. Blood-Based Epigenetic Screen Tests for Diabetes Complications The Scientist: News & Opinion 1 Oct. 2019. Web.