12 Facts About Diabetes Mellitus

iStock/mthipsorn
iStock/mthipsorn

Thirty million Americans—about 9 percent of the country's population—are living with diabetes mellitus, or simply diabetes. This chronic condition is characterized by sustained high blood sugar levels. In many patients, symptoms can be managed with insulin injections and lifestyle changes, but in others, the complications can be deadly. Here's what you need to know about diabetes mellitus.

1. There are three types of diabetes.

In healthy people, the pancreas produces enough of the hormone insulin to metabolize sugars into glucose and move the glucose into cells, where it's used for energy.

But people with type 2 diabetes—the most common form of the disease, accounting for about 95 percent of cases—either can't produce enough insulin to transport the sugars, or their cells have become insulin-resistant. The result is a buildup of glucose in the blood (a.k.a. high blood sugar or hyperglycemia). Type 2 diabetes typically develops in adults.

Type 1 diabetes, also known as juvenile diabetes, makes up the remaining 5 percent of chronic cases and most often develops in children and young adults. With this condition, the initial problem isn’t blood sugar levels, but insulin production: The pancreas can’t make enough insulin to process even normal amounts of glucose. The sugar builds up as a result, leading to dangerous concentrations in the bloodstream.

The third form, gestational diabetes, only afflicts pregnant people who weren’t diabetic before their pregnancy. The mother's blood glucose levels usually spike around the 24th week of pregnancy, but with a healthy diet, exercise, and insulin shots in some cases, diabetes symptoms usually can be managed. Blood sugar levels tend to return to normal in patients following their pregnancies.

2. The mellitus in diabetes mellitus means "honey sweet."

Around 3000 years ago, ancient Egyptians described a condition with diabetes-like symptoms, though it wasn't called diabetes yet. It took a few hundred years before the Greek physician Araetus of Cappodocia came up with the name diabetes based on the Greek word for "passing through" (as in passing a lot of urine, a common diabetes symptom). English doctor Thomas Willis tacked on the word mellitus, meaning "honey sweet," in 1675, building on previous physicians' observations that diabetic patients had sweet urine. Finally, in 1776, another English physician named Matthew Dobson confirmed that both the blood and urine of diabetes patients were made sweeter by high levels of glucose in their blood.

3. The cause of one type of diabetes is well understood; the other, not so much.

A person’s lifestyle is a key predictor of developing type 2 diabetes. Factors like being overweight or obese, consuming a high-calorie diet, smoking, and seldom exercising contribute to the risk. Foods and drinks that are high in sugar—soda, candy, ice cream, dessert— may contribute to hyperglycemia, but any food that’s high in calories, even if it's not sweet, can raise blood sugar levels.

In contrast to these well-established factors, medical experts aren’t entirely sure what causes type 1 diabetes. We do know that type 1 is an autoimmune disease that develops when the body attacks and damages insulin-producing cells in the pancreas. Some scientists think that environmental factors, like viruses, may trigger this immune response.

4. Family history also plays a role in diabetes risk.

If a parent or sibling has type 2 diabetes, you are predisposed to developing pre-diabetes and type 2 diabetes. Lifestyle habits explain some of these incidences, since family members may share similar diets and exercise habits. Genetics also play a role, but just because one close relative has diabetes does not mean you're destined to. Research conducted on identical twins, which share identical genes, showed that the pairs have discordant risk. Among twins in which one has type 1 diabetes, the other has only a 50 percent chance of developing it; for type 2, the risk for the second twin is 75 percent at most.

5. Racial minorities are at a higher risk for developing diabetes.

Many racial minority groups in the U.S. have a higher chance of developing type 2 diabetes. Black Americans, Latino Americans, Native Americans, Pacific Islanders, and some groups of Asian Americans are more likely to have pre-diabetes and type 2 diabetes than white Americans. This can be partly explained by the fact that some of these groups also have higher rates of obesity, which is one of the primary risk factors of type 2 diabetes. Socioeconomics may also play a role: One study shows that people with diabetes living in poverty are less likely to visit diabetes clinics and receive proper testing than their middle-income counterparts. According to another study, diabetic people without health insurance have higher blood sugar, blood pressure, and cholesterol rates than insured diabetics. Genetics, on the other hand, don’t appear to contribute to these trends.

6. Diabetes is one of the world's deadliest diseases.

With proper management, people with diabetes can live long, comfortable lives. But if the disease isn’t treated, it can have dire consequences. Diabetics make up the majority of people who develop chronic kidney disease, have adult-onset blindness, and need lower-limb amputations. In the most serious cases, diabetes leads to death. The condition is one of the deadliest diseases in the world, killing more people than breast cancer and AIDS combined.

7. Millions of Americans are pre-diabetic.

According to the CDC, 84 million adults living in the U.S. are pre-diabetic: Their blood sugar is higher than what’s considered safe, but hasn't yet reached diabetic level. In pre-diabetic patients, blood glucose levels after eight hours of fasting fall between 100 and 125 milligrams per deciliter, and diabetic levels are anything above that. People with pre-diabetes are not just at a greater risk for type 2 diabetes, but also for heart disease and stroke. Fortunately, people who are diagnosed with pre-diabetes can take steps to eat a healthier diet, increase physical activity, and test their blood glucose level several times a day to control the condition. In some cases, doctors will prescribe drugs like metformin that make the body more receptive to the insulin it produces.

8. After climbing for decades, rates of diabetes incidence are declining.

In the U.S., the rate of new diagnoses skyrocketed 382 percent between 1988 and 2014. Globally, 108 million people had diabetes in 1980, but by 2014 that number was 422 million.

But thanks to nationwide education and prevention efforts, the trend has reversed in the U.S., according to the CDC. Since peaking in 2009, the number of new diabetes cases in America has dropped by 35 percent. In that same timeframe, the number of people living with diagnosed diabetes in the U.S. has plateaued, suggesting people with the condition are living longer.

9. The first successful treatment for type 1 diabetes occurred in 1922.

Prior to the 20th century, type 1 diabetes was usually fatal. Diabetic ketoacidosis—a toxic buildup of chemicals called ketones, which arise when the body can no longer use glucose and instead breaks down other tissues for energy—killed most patients within a year or two of diagnosis. In searching for way to save children with juvenile (type 1) diabetes, Canadian physician Frederick Banting and medical student Charles Best built on the work of earlier researchers, who had demonstrated that removing the pancreas from a dog immediately caused diabetes symptoms in the animal. Banting and Best extracted insulin from dog pancreases in University of Toronto professor J.J.R. Macleod's lab. After injecting the insulin back into dogs whose pancreases had been removed, they realized the hormone regulated blood sugar levels. On January 11, 1922, they administered insulin to a human patient, and further refined the extract to reduce side effects. In 1923, Banting and Macleod received the Nobel Prize in Medicine for their work.

10. A pioneering physicist discovered the difference between type and and type 1 diabetes.

In the 1950s, physicist Rosalyn Yalow and her research partner Solomon Berson developed a method for measuring minute amounts of substances in blood. Inspired by Yalow's husband's struggle with diabetes, Yalow focused her research on insulin. Their "radioimmunoassay" technology revealed that some diabetes patients were still able to produce their own insulin, leading them to create two separate categories for the disease: “insulin-dependent” (type 1) and “non-insulin-dependent” (type 2). Prior to that discovery in 1959, there was no distinction between the two types. In 1977, Yalow won the 1977 Nobel Prize in Medicine for the radioimmunoassay, one of only 12 female Nobel laureates in medicine.

11. Making one insulin dose once required tons of pig parts.

Insulin is relatively easy to make today. Most of what's used in injections comes from a special non-disease-producing laboratory strain of E. coli bacteria that's been genetically modified to produce insulin, but that wasn't always the case. Until about 40 years ago, 2 tons of pig pancreases were required to produce just 8 ounces of pure insulin. The pig parts were typically recycled from pork farms.

12. A quarter of diabetes patients don’t know they have it.

The symptoms of type 2 diabetes can develop for years before patients think to ask their doctor about them. These include frequent urination, unexplained thirst, numbness in the extremities, dry skin, blurry vision, fatigue, and sores that are slow to heal—signs that may not be a cause for concern on their own, but together can indicate a more serious problem. Patients with type 1 diabetes may also experience nausea, vomiting, and stomach pain.

While serious, the symptoms of diabetes are sometimes easy to overlook. That’s why 25 percent of people with the illness, 7.2 million in the U.S., are undiagnosed. And that number doesn’t even cover the majority of people with pre-diabetes who aren’t aware they’re on their way to becoming diabetic.

7 Facts About Blood

Moussa81/iStock via Getty Images
Moussa81/iStock via Getty Images

Everyone knows that when you get cut, you bleed—a result of the constant movement of blood through our bodies. But do you know all of the functions the circulatory system actually performs? Here are some surprising facts about human blood—and a few cringe-worthy theories that preceded the modern scientific understanding of this vital fluid.

1. Doctors still use bloodletting and leeches to treat diseases.

Ancient peoples knew the circulatory system was important to overall health. That may be one reason for bloodletting, the practice of cutting people to “cure” everything from cancer to infections to mental illness. For the better part of two millennia, it persisted as one of the most common medical procedures.

Hippocrates believed that illness was caused by an imbalance of four “humors”—blood, phlegm, black bile, and yellow bile. For centuries, doctors believed balance could be restored by removing excess blood, often by bloodletting or leeches. It didn’t always go so well. George Washington, for example, died soon after his physician treated a sore throat with bloodletting and a series of other agonizing procedures.

By the mid-19th century, bloodletting was on its way out, but it hasn’t completely disappeared. Bloodletting is an effective treatment for some rare conditions like hemochromatosis, a hereditary condition causing your body to absorb too much iron.

Leeches have also made a comeback in medicine. We now know that leech saliva contains substances with anti-inflammatory, antibiotic, and anesthetic properties. It also contains hirudin, an enzyme that prevents clotting. It lets more oxygenated blood into the wound, reducing swelling and helping to rebuild tiny blood vessels so that it can heal faster. That’s why leeches are still sometimes used in treating certain circulatory diseases, arthritis, and skin grafting, and helps reattach fingers and toes. (Contrary to popular belief, even the blood-sucking variety of leech is not all that interested in human blood.)

2. Scientists didn't understand how blood circulation worked until the 17th century.

William Harvey, an English physician, is generally credited with discovering and demonstrating the mechanics of circulation, though his work developed out of the cumulative body of research on the subject over centuries.

The prevailing theory in Harvey’s time was that the lungs, not the heart, moved blood through the body. In part by dissecting living animals and studying their still-beating hearts, Harvey was able to describe how the heart pumped blood through the body and how blood returned to the heart. He also showed how valves in veins helped control the flow of blood through the body. Harvey was ridiculed by many of his contemporaries, but his theories were ultimately vindicated.

3. Blood types were discovered in the early 20th century.

Austrian physician Karl Landsteiner discovered different blood groups in 1901, after he noticed that blood mixed from people with different types would clot. His subsequent research classified types A, B and O. (Later research identified an additional type, AB). Blood types are differentiated by the kinds of antigens—molecules that provoke an immune system reaction—that attach to red blood cells.

People with Type A blood have only A antigens attached to their red cells but have B antigens in their plasma. In those with Type B blood, the location of the antigens is reversed. Type O blood has neither A nor B antigens on red cells, but both are present in the plasma. And finally, Type AB has both A and B antigens on red cells but neither in plasma. But wait, there’s more! When a third antigen, called the Rh factor, is present, the blood type is classified as positive. When Rh factor is absent, the blood type is negative.

Scientists still don’t understand why humans have different blood types, but knowing yours is important: Some people have life-threatening reactions if they receive a blood type during a transfusion that doesn’t “mix” with their own. Before researchers developed reliable ways to detect blood types, that tended to turn out badly for people receiving an incompatible human (or animal!) blood transfusion.

4. Blood makes up about 8 percent of our total body weight.

Adult bodies contain about 5 liters (5.3 quarts) of blood. An exception is pregnant women, whose bodies can produce about 50 percent more blood to nourish a fetus.)

Plasma, the liquid portion of blood, accounts for about 3 liters. It carries red and white blood cells and platelets, which deliver oxygen to our cells, fight disease, and repair damaged vessels. These cells are joined by electrolytes, antibodies, vitamins, proteins, and other nutrients required to maintain all the other cells in the body.

5. A healthy red blood cell lasts for roughly 120 days.

Red blood cells contain an important protein called hemoglobin that delivers oxygen to all the other cells in our bodies. It also carries carbon dioxide from those cells back to the lungs.

Red blood cells are produced in bone marrow, but not everyone produces healthy ones. People with sickle cell anemia, a hereditary condition, develop malformed red blood cells that get stuck in blood vessels. These blood cells last about 10 to 20 days, which leads to a chronic shortage of red blood cells, often causing to pain, infection, and organ damage.

6. Blood might play a role in treating Alzheimer's disease.

In 2014, research led by Stanford University scientists found that injecting the plasma of young mice into older mice improved memory and learning. Their findings follow years of experiments in which scientists surgically joined the circulatory systems of old and young mice to test whether young blood could reverse signs of aging. Those results showed rejuvenating effects of a particular blood protein on the organs of older mice.

The Stanford team’s findings that young blood had positive effects on mouse memory and learning sparked intense interest in whether it could eventually lead to new treatments for Alzheimer’s disease and other age-related conditions.

7. The sight of blood can make people faint.

For 3 to 4 percent of people, squeamishness associated with blood, injury, or invasive medical procedures like injections rises to the level of a true phobia called blood injury injection phobia (BII). And most sufferers share a common reaction: fainting.

Most phobias cause an increase in heart rate and blood pressure, and often muscle tension, shakes, and sweating: part of the body’s sympathetic nervous system’s “fight or flight” response. But sufferers of BII experience an added symptom. After initially increasing, their blood pressure and heart rate will abruptly drop.

This reaction is caused by the vagus nerve, which works to keep a steady heart rate, among other things. But the vagus nerve sometimes overdoes it, pushing blood pressure and heart rate too low. (You may have experienced this phenomenon if you’ve ever felt faint while hungry, dehydrated, startled, or standing up too fast.) For people with BII, the vasovagal response can happen at the mere sight or suggestion of blood, needles, or bodily injury, making even a routine medical or dental checkup cause for dread and embarrassment.

9 Surprising Facts About the Scientific Study of Sex

vadimguzhva/iStock via Getty Images
vadimguzhva/iStock via Getty Images

The scientific study of sex is much more exciting than an awkward sex ed class. While writing my book Sex Weird-o-Pedia, these were some of the most interesting facts about science and sex that I came across.

1. Some sex researchers didn't want their findings to get into the wrong hands.

The pioneering sex researcher Richard von Krafft-Ebing didn’t want his knowledge in the hands of ordinary folk. So he wrote Psychopathia Sexualis, the founding document of modern sexology—which was published in Germany in 1886 then translated and published in English in 1939—in Latin to discourage regular Joes (and/or Janes) from reading it.

2. You burn more calories mowing the lawn than you do having sex.

Young woman poses for selfie while mowing the lawn
Alina Rosanova/iStock via Getty Images

Sex might seem strenuous when things get hot and heavy, but it's usually not that great of a workout. You'd have to go at it for nearly 200 minutes to burn as much energy having sex as you do during a 30-minute run. Even mowing the lawn burns about three times more calories than sex. According to the British Heart Foundation, sex burns about the same amount of energy per minute as ironing clothes.

3. A surprising number of mothers claim to be virgins.

In a 2013 study of several thousand pregnant women in the U.S. published by BMJ, about 1 percent of the participants claimed they were virgins when they gave birth. This, of course, calls into question the veracity of studies that rely on self-reported sexual behaviors.

4. Penicillin may have ignited the sexual revolution.

One economist says that penicillin, and not the birth control pill, was the real enabler of the sexual revolution. A study published in the Archives of Sexual Behavior in 2013 shows that penicillin contributed to a 75 percent decline in the number of deaths caused by syphilis from 1947 to 1957. Since the new treatment made sex safer, people started having riskier sex, which resulted in increases in the numbers of children born out of wedlock and teenage pregnancies.

5. Twins can have different dads.

A photo of fraternal twins
Aleksandr Zhurilo/iStock via Getty Images

While it is very rare, it is possible for fraternal twins to have two different fathers. What’s more common is for a rom-com to be based on this scenario.

6. Gender may influence how people handle sexual jealousy.

Research from evolutionary psychologists indicates that people’s gender influences how they react to sexual jealousy. For men, they react more strongly to sexual unfaithfulness than emotional infidelity. For women, it is the reverse. The theory behind these behaviors comes back to evolution: Males who were intolerant toward their wives becoming sexually active with other men were less likely to become an object of derision and more likely to see their own genes pass onto future generations. Women who prevented their husbands from emotionally bonding with other women reduced the chances of the men spending their resources on other women.

7. One of Ivan Pavlov's colleagues created his own (slightly x-rated) conditioning experiment with dogs.

You’re probably aware of Russian researcher Ivan Pavlov and his famous conditioning experiment in which he trained a dog to salivate at the sound of a bell. What you might not know is that one of Pavlov’s American students, W. Horsley Gantt, conditioned dogs to become sexually aroused when they heard specific tones. The experiment, according to Mandy Merck's In Your Face: 9 Sexual Studies, was intended "to study conflicts of the drives between ... experimentally induced anxiety states and sexual excitement."

8. Couples whose first child is a girl are more likely to get divorced.

Parents pay attention to their phones instead of their daughter
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Married couples whose first child is a girl are more likely to get divorced than those whose first child is a boy. Scientists are split as to why this is. One theory is that female embryos are better able to endure maternal stress than male embryos, so pregnant women in unhappy marriages are less likely to have a miscarriage if the child they are bearing is a girl. But once they have a daughter, these couples are more likely to split up since there were already fissures in their relationship prior to the child’s birth.

9. There's a link between pubic hair and STIs.

A downside of pubic grooming is that it might raise STI risk. In a study conducted by a University of Texas scholar, people who regularly shaved their pubic areas contracted STIs about 80 percent more often than those who never shaved down there. One suggestion is that those who regularly shave are more likely to tear their skin, making it easier for viruses to enter the body.

Ross Benes is the author of Sex Weird-o-Pedia: The Ultimate Book of Shocking, Scandalous, and Incredibly Bizarre Sex Facts.

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