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Normal Blood Sugar Levels Chart By Age
Blood sugar, or glucose, is the primary type of sugar in the body. It comes from carbohydrates found in foods. Glucose is essential for providing energy to cells throughout the body, including brain cells.
Your blood sugar level fluctuates throughout the day as you eat, exercise and sleep. Stress and hormones also play a role. People with diabetes should monitor blood sugar levels closely to ensure they remain within the appropriate target range—often determined by a medical provider.
A blood sugar level outside the target range can have profound health implications. "When blood sugar levels are too high or too low, it can have serious health consequences, such as nerve damage, kidney damage and heart disease," says Brenda Peralta, registered dietitian and certified diabetes educator at FeastGood.Com.
High blood sugar (hyperglycemia) can lead to conditions like diabetes, cardiovascular disease and stroke, she explains. Low blood sugar (hypoglycemia) can cause confusion, anxiety, weakness, sweating and vision problems. Extremely low levels of blood sugar can result in seizures and fainting.
Why Does Blood Sugar Matter With Diabetes?Diabetes is a condition that makes it difficult or impossible for the body to regulate glucose levels on its own. When someone is living with diabetes, their body is either unable to produce enough insulin—or make enough insulin available for use. Insulin is a hormone that helps the body use glucose for energy. When insulin levels are too low, glucose accumulates in the bloodstream and can damage organs and other tissues.
"Diabetes occurs when a person's body cannot adequately manage sugar that's ingested normally in our everyday diet," says Jennifer Meller, M.D., chief medical officer at Sweetch—a digital health care innovation company based in Tel Aviv, Israel. "Chronically elevated sugar levels can lead to changes in both large and small blood vessels."
Over time, changes to large vessels can lead to an increased risk of heart attack and stroke, while damage to small vessels can cause nerve damage, vision loss and kidney failure, explains Dr. Meller.
For people living with diabetes, maintaining healthy blood sugar levels is essential to preventing serious health complications in the future. This requires understanding target glucose levels for different age groups and making lifestyle changes accordingly, as blood sugar can go up or or down based on what you eat and when, among other factors.
What Is an A1C Number?An A1C test, also called glycosylated hemoglobin, is a standard diagnostic tool used to measure a person's average blood sugar levels over the past three months (90 days). It reflects how well your blood sugar is controlled during that time period.
"It's an essential measure of blood sugar control in diabetes because it provides a long-term view of blood sugar levels and can help predict the risk of complications from diabetes," explains Peralta.
The test uses a small blood sample to analyze the amount of hemoglobin—a protein found in red blood cells that carries oxygen and binds to glucose molecules. The higher the glucose level in your bloodstream, the more hemoglobin will bind to it and be detected by the A1C test. This test is often done with a finger prick in the doctor's office..
An A1C number is expressed as a percentage, with higher percentages indicating higher levels of glucose in the bloodstream. A healthy A1C reading for someone without diabetes is between 4% and 5.7%. A value between 5.7% and 6.4% is considered prediabetic, while 6.5% and higher are consistent with diabetes .
One important note to consider about one's A1C number is that it may be affected by other medical conditions such as anemia, which could result in an inaccurate reading. This is why looking at additional numbers, such as one's fasting glucose, in conjunction with an A1C number, is usually recommended.
Restoring The Blood-brain Barrier?
There's a bouncer in everyone: The blood-brain barrier, a layer of cells between blood vessels and the rest of the brain, kicks out toxins, pathogens and other undesirables that can sabotage the brain's precious gray matter.
When the bouncer is off its guard and a rowdy element gains entry, a variety of conditions can crop up. Barrier-invading cancer cells can develop into tumors, and multiple sclerosis can occur when too many white blood cells slip pass the barrier, leading to an autoimmune attack on the protective layer of brain nerves, hindering their communication with the rest of the body.
"A leaky blood-brain barrier is a common pathway for a lot of brain diseases, so to be able to seal off the barrier has been a long sought-after goal in medicine," said Calvin Kuo, MD, PhD, the Maureen Lyles D'Ambrogio Professor and a professor of hematology.
Methods of repairing the blood-brain barrier remain understudied, according to Kuo. But a recent paper he and colleagues led describes a treatment that could be instrumental in restoring the barrier's normal function. Kuo is the senior author of the paper, published in Nature Communications on June 2.
"We have evaluated a new therapeutic class of molecules that can be used to treat a leaky blood-brain barrier; previously, there were no treatments directed at the blood-brain barrier specifically," Kuo said.
The researchers started their quest by looking at WNT signaling, a communication pathway used by cells to promote tissue regeneration and wound healing. WNT signaling helps maintain the blood-brain barrier by promoting cell-to-cell communication that lines brain blood vessels.
"There's a lot of historical data that indicated that the WNT signaling pathway would be important for maintaining the blood-brain barrier," Kuo said. "The opportunity arose to test a novel WNT signaling pathway that would turn on signaling in the blood-brain barrier by binding very selectively to a receptor called frizzled."
Scientists have been focusing on frizzled, a protein receptor that initiates the WNT pathway, for blood-brain barrier therapies since mouse mutations in the frizzled gene cause blood-brain barrier abnormalities.
How it's made
Many different molecules bind to frizzled protein receptors, so to narrow their search for a potential therapeutic molecule, the researchers selected only those that specifically target cells that line the brain's blood vessels.
Chris Garcia, PhD, a professor of molecular and cellular physiology as well as the Younger Family Professor, developed prototype therapeutic WNT pathway molecules in the lab, including a molecule that activates the frizzled receptor FZD4. Building off of the work of Garcia and Kuo, collaborators at a research company created L6-F4-2, a FZD4 binding molecule that activates WNT signaling 100 times more efficiently than other FZD4 binders.
When the team, including Jie Ding, a research scientist and the lead author of the paper, activated WNT signaling at a higher rate, they saw an increase in blood-brain barrier strength.
Keeping the bouncer on duty
The researchers wanted to study what happens when the natural molecular key for frizzled is missing, and whether it can be replaced successfully with L6-F4-2. So they turned to Norrie disease, a genetic abnormality that results in a leaky blood-retinal barrier.
The blood-retinal barrier performs the same function for the eye as the blood-brain barrier does for the brain. In Norrie disease, the development of blood vessels of the retina -- the layer of light-sensitive cells in the back of the eye -- is hindered, resulting in leaky blood vessel connections, improper development and blindness.
Norrie disease results from mutations in the NDP gene, which provides instructions for making a protein called Norrin, which is the key that fits the lock of the FZD4 receptor and turns it on. In the study's mice, the gene is inactivated, and the key is missing causing a leaky barrier and blindness. The scientists replaced the missing Norrin protein with L6-F4-2, which they call a surrogate.
When L6-F4-2 replaced the missing Norrin protein, the blood-retinal layer was restored in the mice. Researchers knew this because they imaged the blood vessels and found them to be denser, and less leaky, than before treatment. Scientists also showed that, for the blood-brain barrier surrounding the mice cerebellum -- a region responsible for muscle coordination -- L6-F4-2 replaced Norrin and activated WNT signaling.
Next, the researchers wanted to study a more common human condition -- ischemic stroke (in which blood vessels and the blood-brain barrier are damaged, and fluid, blood and inflammatory proteins involved in cellular communication can leak into the brain. They found that L6-F4-2 reduced the severity of stroke and improved survival of mice compared with mice that had untreated strokes. Importantly, L6-F4-2 reversed the leakiness of brain blood vessels after stroke. Mice treated with L6-F4-2 had increased stroke survival, compared to those that were not treated.
The finding shows that, in mice, the blood-brain barrier could be restored by drugs that activate FZD receptors and the WNT signaling pathway.
Because a variety of disorders have their origin in blood-brain barrier dysfunction, Kuo is excited about the treatment potential for a variety of other neurological diseases, such as Alzheimer's, multiple sclerosis and brain tumors.
"We hope this will be a first step toward developing a new generation of drugs that can repair the blood-brain barrier, using a very different strategy and molecular target than current medications," Kuo said.
This Small Hampden Company Is Trying To Solve A Century-old Question: How Do Doctors Bypass The Blood-brain Barrier?
In a laboratory in Germany nearly 140 years ago, a scientist injected dye into the bloodstream of a mouse and found something puzzling: The dye slowly spread to every organ in the creature's tiny body, except its brain.
The scientist, Paul Ehrlich, had discovered the blood-brain barrier, a specialized sheath of interlocking cells that block substances from leaving the brain's blood vessels and interacting with the rest of the organ. Similar to how the skull protects the brain from physical injury, the blood barrier protects the brain from disease-causing pathogens and toxins that may be circulating in the bloodstream.
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The barrier, however, also blocks most drugs from accessing the brain to treat mental and neurological disorders.
For decades, scientists have been trying to find ways to bypass the blood-brain barrier to fight deadly and debilitating diseases like brain cancer, Alzheimer's and Parkinson's. While they have made progress at major research institutions like the University of Maryland School of Medicine in Baltimore, leaders at a small company in Hampden say they believe the next milestone in the field will come from their team.
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The company, CraniUS, hopes to soon begin human trials on a device designed to be implanted in the skull space and deliver medicine directly to the brain through catheters. Should everything go according to plan, the company will seek approval from the U.S. Food and Drug Administration for a human study by the end of next year and begin the first trial in 2025, CEO Mike Maglin said.
"Think about not only the drugs that are out there that are challenged because of the blood-brain barrier, [but also the ones] that quite frankly companies have stopped developing because of the blood-brain barrier," Maglin said. "We believe this is also going to be a conduit for new drug development, as well as hopefully resuscitating or keeping some of the drug options on the table that are out there today."
CraniUS was co-founded in Baltimore in 2021 by Dr. Chad Gordon, the director of neuroplastic and reconstructive surgery at Johns Hopkins Medicine, and Deborah Weidman. Last year, the company announced that it raised $20 million in its first round of fundraising, entirely from private investors.
Scot Stone, senior vice president of Medical Products Laboratories — a Philadelphia-based drug manufacturer that is working with CraniUS — is one of the company's investors. He was drawn to the company after listening to presentations from Gordon, who is also his childhood friend. Stone's father, Elliot Stone, the president and CEO of Medical Products Laboratories, sits on CraniUS' board of directors.
"From the very first time, the way he described the technology, the innovation and what this device would mean to the industry," Stone said, "it really caught our attention."
In an experiment conducted in Boston last month, the patented device CraniUS is developing — NeuroPASS — showed promising results, the company said in a news release published Tuesday morning. Researchers implanted the device in a pig skull and, according to MRI images, it successfully delivered a substance directly to the animal's brain.
Leaders are in talks with the FDA to conduct the necessary verification and validation testing to get approval to start studying the device in humans, Gordon said. But results from the preclinical study showed that the device can safely and effectively bypass the blood-brain barrier in a pig — a 200-pound animal with a brain similar to a human brain.
"That's why we're so enthusiastic about this hurdle that we just overcame," Gordon said. "Because we think the other hurdles in front of us are less daunting."
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The NeuroPASS device builds on a method of medicine delivery introduced in the 1990s by a doctor at the National Institutes of Health called convection-enhanced delivery. In this technique, one or more catheters are placed in the brain and an infusion pump is used to transport medication directly into the organ.
Research on that method has progressed in "fits and starts" over the last three decades, said Dr. David Daniels, a pediatric neurosurgeon at the Mayo Clinic in Minnesota. A number of research teams are studying it across the country, including a team led by Daniels, which is working to identify ways to keep medication in the brain for a longer period of time once it gets past the blood-brain barrier.
"Our take-home message is that we think some of the old studies failed because we didn't know where the drug was going, and we're not keeping it there long enough to have the appropriate effect," Daniels said. "If you can overcome that, maybe it has merit."
While convection-enhanced delivery remains an experimental treatment, Daniels expects that one day it will be commonplace for treating the kind of tumor he studies — diffuse intrinsic pontine glioma, which usually occurs in children and forms on the brain stem. Fewer than 1 in 10 children diagnosed with this type of tumor survive beyond two years.
The team behind NeuroPASS says its device is unique because it is implanted into the skull space, allowing medication to be administered over time, rather than only in a hospital setting or doctor's office. The device also has a refillable reservoir — similar to a chemo port used in breast cancer patients — and is designed to be recharged wirelessly.
That means if a cancer patient has a recurring brain tumor, doctors could refill the medication in the device and start treatment without delay, said Dr. Henry Brem, director of Johns Hopkins Medicine's Department of Neurosurgery.
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Brem sits on the CraniUS board of directors and, in the 1980s, invented the Gliadel Wafer, a biodegradable polymer that's placed in the brain to bypass the blood-brain barrier and release chemotherapy directly to a tumor. While the technology prolongs the survival of people with brain cancer, unlike NeuroPASS, the medication it delivers can't be replenished.
"The reason I joined the board is I wanted to do everything possible to facilitate [the NeuroPASS] being available for patients," Brem said, "because I think it's a real breakthrough technology."
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By submitting your email to receive this newsletter, you agree to our Subscriber Terms & Conditions and Privacy Policy.Daniels said an invention like NeuroPASS, which places a device in a cranioplasty implant, has merit.
But he added that cranioplasty, a type of surgery that involves repairing or reshaping a person's skull, has a higher risk of infection than other types of cranial surgeries. And he hasn't seen data from testing of the device or seen the device itself.
Advancements in treating glioblastomas — fast-growing and aggressive brain tumors that typically kill people in about 12 to 15 months — also have been made at the University of Maryland School of Medicine. In a study conducted at the facility, researchers used focused ultrasound and a bubbling agent to create temporary leaks in the blood-brain barrier so that chemotherapy could get to the tumors.
In 2022, three years after the study took place, most of the 14 people who received the experimental procedure were still alive.
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CraniUS is using a chemotherapy drug called Topotecan in its initial tests, since the drug already has been tested for direct delivery to the brain. But in the future, Maglin and Gordon hope drug companies will use the NeuroPASS to administer drugs to fight other brain diseases.
They added that credit for the progress their company has achieved is shared with the team of more than a dozen engineers behind the development of NeuroPASS.
"It takes a special talent to be able to actually think about what we're trying to accomplish, and then actually build it," Maglin said. "There are engineers all over the world that are making things incrementally better. We're looking for people who are actually breaking new ground — so pioneers, not engineers. That's the team we have."
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