Fortunately, medicine has come a long way since the Middle Ages, but one early practice might be coming back: bloodletting.
Bloodletting, a process in which units of blood are drawn to cure or prevent disease, has a history spanning 3,000 years. The practice was used to cure ailments including the plague, smallpox, epilepsy and gout, and it was performed regularly until the late 19th century.
Now, bloodletting is thought to be a potential treatment for type 2 diabetes, and an upcoming study from the UNC School of Medicine and Wake Forest University—the largest and longest human study of its kind—is aiming to better understand the link.
“This is the first big enough study that, if blood drawing is really a reasonable way of treating diabetes in the future, we’ll be able to show that,” says John Buse, MD, PhD, director of the UNC Diabetes Care Center and chief of the Division of Endocrinology and Metabolism.
The Diabetes-Bloodletting Connection
One of the liver’s central roles is providing sugar to the brain between meals for energy. “Our body stores energy in the form of fat, and there are limited stores of carbohydrates,” Dr. Buse says. “But the liver can convert the protein in muscle and fat and turn it into sugar to feed the brain.”
In people who have diabetes, the liver will repeat this process and produce excess sugar, even when blood sugar levels are high.
Although why this happens isn’t clear, one thing that might be at play is iron.
“We don’t really know why that relationship exists,” Dr. Buse says. “But high iron is associated with changes in the way that the liver works, as well as the way that insulin and fat cells work. So, this iron-associated liver abnormality could be connected to the liver making sugar when it shouldn’t be making sugar.”
This means that people with high iron levels are also at higher risk of diabetes. High iron is also a risk factor for one of diabetes’ biggest complications, nonalcoholic steatohepatitis (NASH), or fatty liver disease.
In studies with rodents, there’s extensive evidence that reducing iron levels through blood drawing can have beneficial, even curative, properties.
“Based off these studies, researchers developed a theory that, in humans, part of the reason why we have this diabetes epidemic is not just because we’ve eaten too many calories and gained weight,” Dr. Buse says. “It’s more specifically that iron is a nutrient, and too much of it is a problem. So, if we use blood drawing as a technique to get iron out of the body, then perhaps we can improve metabolism and diabetes.”
How the Bloodletting Study Will Work
To date, there are limited human studies looking into how bloodletting may help manage diabetes, which will make the research from UNC and Wake Forest the first long-term study of its kind. The research will include 240 volunteers, ages 40 to 75, who will have their blood drawn regularly for up to 18 months. The study is currently enrolling volunteers.
“What we’re going to do is find people with diabetes or prediabetes, which means they’re close to having diabetes but there hasn’t been an official diagnosis, and select those with good iron stores,” Dr. Buse says. Half of the volunteers will have prediabetes, while the other half will have early type 2 diabetes and be on up to two blood sugar medications, not including insulin.
“If volunteers agree, we’ll schedule them for a series of visits at which we will draw off a unit of blood while checking for safety and blood sugar responses,” he says.
Unlike ancient bloodletting practices—which included leeches and scarification, in which the skin was scraped using a device with multiple small blades—modern techniques follow the same procedure as regular blood donation. Doctors will draw one unit of blood, about one pint. This will happen every eight weeks, the same frequency permitted of a regular blood donor.
Some volunteers will go through a placebo version of this process. “This means the person is going to get a needle in the arm as if blood was being drawn, but we’re not going to draw their blood,” Dr. Buse says. All volunteers will wear an eye mask during this process so they won’t know whether they’re getting the real treatment.
Half of the volunteers will be at UNC, while the rest will be at Wake Forest. Wake Forest researchers will also be looking specifically at the relationship between iron and the liver complication NASH.
As for where bloodletting might fit into a person’s treatment plan, Dr. Buse says that’s part of the study, too. Including people with prediabetes along with those already diagnosed will help determine where bloodletting may be most beneficial throughout different stages of the disease.
If the study shows that bloodletting is a viable treatment, the researchers will publish a paper for the medical community to decide whether to recommend it to patients.
“My guess is that it would be popular, because it’s relatively inexpensive and natural; there is no real safety concern compared with a drug,” Dr. Buse says. “I personally think if this is successful, it’s going to be groundbreaking. If bloodletting is as successful in humans as in mice, people may not need as many drugs to manage disease and have the opportunity to prevent disease altogether.”
The Future of Blood Donation
Other than managing and potentially treating diabetes, the implications of the study could also change the future of blood donation.
Normally when someone donates blood, it’s used in transfusions, where the blood is given to someone in need. For instance, if someone is injured in a traffic crash and has extensive blood loss, he or she may require a blood transfusion.
During the study, however, the blood will have to be discarded, as current regulations say that blood has to be freely donated—and therefore can’t be obtained as part of a study—to be used toward transfusions.
“In the future, if the results of the study are successful and we are able to show that regular blood donations are associated with reduction in blood sugar for people with prediabetes or diabetes, I’m sure that will only enhance the ability of the Red Cross and others to encourage people to donate blood,” Dr. Buse says. “I think people will see donating blood as both being a good thing for society and something beneficial for their health.”
To learn more about clinical trials at UNC, visit Join the Conquest, an online resource for clinical trials information and enrollment.