Dear Doctors: Is there more than one kind of COVID-19? I heard on the news about something they’re calling “long COVID,” and it sounds like a whole different kind of disease. How do you get it? Can it be cured?

Dear Reader: It’s true that we’re hearing a lot about long COVID these days. Despite being referred to by a different name than COVID-19, it’s not a separate illness. Rather, long COVID is a term used to describe the lingering symptoms that can affect some people who have survived COVID-19. People who are experiencing long COVID are sometimes referred to as "COVID long-haulers."

As we know all too well by now, COVID-19 is the name of the illness that can arise when someone becomes infected with the novel coronavirus. Cases of COVID-19 run the gamut from mild to moderate to severe to fatal. One of the perils of the disease is that it’s impossible to predict how any one person will react to the infection. Even a moderate case of COVID-19 can be challenging, with symptoms that include high fever, body aches, congestion, difficulty breathing, dizziness, profound fatigue and altered mental status. For many people with moderate to severe COVID-19, the disease runs its course in a month or more. However, tens of thousands of survivors experience long COVID, or long-haul COVID, and some symptoms persist.

For these COVID survivors, recovery is long and rocky, marked by repeated setbacks. Even when the worst of the disease has run its course, other symptoms affect patients for many months. These include persistent fatigue, exhaustion, headache, muscle aches, muscle spasms, erratic heartbeat, depression, low blood pressure after exertion and memory fog. Some patients experience increased blood clotting, which can lead to organ damage.

A recent study published in the Journal of the American Medical Association followed the recovery of 145 patients in their 50s who had experienced moderate to severe COVID-19 symptoms. Researchers found that 87% were left with labored breathing and persistent fatigue for months after the initial disease. Another troubling aspect of long COVID is emerging evidence that it can affect the youngest survivors. About 10% of the more than 11 million coronavirus infections reported in the U.S. thus far have occurred in children, and many experience long-lasting symptoms.

It’s still not clear why some people recover completely from COVID-19, while for others symptoms persist for months. One theory is that, even after someone recovers from the initial disease, fragments of the genetic code of the coronavirus may continue to circulate throughout the body. Although these fragments don’t cause full-on disease, they may continue to trigger an immune system response.

At this time, as with COVID-19, there is no single cure for long COVID. Treatment focuses on managing symptoms. However, it has been recognized as a serious problem. Researchers are now launching studies to discover the biological and immunological causes of long-haul COVID. The hope is to identify any biomarkers that make people susceptible to the syndrome and point to successful treatments.

(Send your questions to askthedoctors@mednet.ucla.edu. Owing to the volume of mail, personal replies cannot be provided.)

Hello again, dear readers, and welcome back to our monthly letters column. Like many of you, we’re adjusting to shorter days and longer nights, and we are gearing up for the challenges of winter. This makes us even more appreciative of your staying in touch.

-- Regarding a column about older adults and falling, a reader from Wallingford, Connecticut, asked us to add an important risk factor to the list. “Distractions were not noted in the article,” he wrote. “Distractions can make a loose carpet, stairs and other obstacles even more dangerous. And distractions are spontaneous, which makes them even more dangerous. ‘Once you take your eye off the ball, get ready for a fall.’" Agreed, and thank you.

On that same topic, a reader asked why we said that even a minor injury from a fall can affect quality of life. Although straining a muscle or twisting an ankle aren’t in the league of a broken bone, they do cause pain, restrict movement and affect mobility. Each of those things makes getting through the day more of a challenge.

-- A reader from Virginia Beach, Virginia, who started a fitness plan with her husband, wonders what qualifies as water. “I don’t love having water early in the day, so I drink several cups of tea, all using the same teabag,” she wrote. “I count the tea as water, but my husband insists only plain water really counts. Do I need to switch?” Although caffeine has a mild diuretic effect, it’s not nearly enough to offset the hydration of a cup of tea. Plus, you’re stretching a single teabag to three cups of tea, so, yes, your morning beverage ritual counts toward your daily water total.

-- A recent column about vitamin D included guidelines for both vitamin supplements and sun exposure. “What about those of us who have had skin cancer, including melanoma, and need to avoid sunlight?” a reader asked. “How much vitamin D should we get from vitamin supplements?” This is important, so we’re happy to repeat our advice: People with any history of skin cancer, or who are at risk for skin cancer, should rely on diet and vitamins for their daily allowance of vitamin D.

-- In response to a column that referenced wigs for cancer patients, a reader from Nags Head, North Carolina, shared a discovery about medical expenses. “I was very surprised to learn wigs are a write-off on the annual returns!” he wrote. “Had we known, my wife probably would have gotten the more expensive natural hair wig she felt better in, rather than the cheaper wig she didn’t really like. Please let your readers know this very important fact.” You’re correct that the costs of a wig for hair loss due to a medical condition, such as alopecia or cancer treatments, are tax deductible.

We’ll close with a reminder that we can’t offer a diagnosis or a second opinion, and we can’t comment on specific treatments or medications. Also, we continue to get requests for previous columns. The good news is that a searchable archive is available online at uexpress.com/ask-the-doctors.

(Send your questions to askthedoctors@mednet.ucla.edu. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctors: We keep hearing about Type 2 diabetes, and I’m embarrassed to say, I don’t actually know what it is. What does it do, and how do I know if I have it?

Dear Reader: To understand diabetes, we should first talk about glucose. That’s the sugar our bodies make from the foods that we eat, and which our cells use as their main source of fuel. Glucose travels throughout the body via the blood, which is why it’s also often referred to as blood sugar. However, it’s not immediately available to the cells. That’s where insulin, a hormone manufactured by the pancreas, comes into play. Insulin helps transport glucose from the blood into the cells, where it can be used as energy.

When someone has diabetes, it means that the insulin part of that energy equation isn’t working properly. Either the body isn’t manufacturing enough -- or any -- insulin, or it isn’t responding properly to the insulin that is present. That leads to blood-glucose levels that are too high.

Over time, high blood levels of glucose are dangerous. Adverse health effects include damage to the circulatory system, vision problems, nerve damage, stomach or intestinal problems, slow healing, kidney disease and an increase in the risk of heart disease and stroke. Extremely high blood sugar levels can lead to coma, and even death.

In Type 1 diabetes, the pancreas makes little or no insulin. It often develops early in life, but can occur at any age. This type of diabetes is managed with diet and exercise, plus the use of medications and insulin.

Type 2 diabetes, once referred to as adult-onset diabetes, often develops later in life. It occurs when the body doesn’t make or use insulin well. Type 2 diabetes often begins as insulin resistance, which is a condition in which the body stops responding properly to the insulin in the blood. This leads to a loss of the ability to control blood sugar.

Some people can manage Type 2 diabetes with diet and exercise alone. Others may also need medication or insulin to keep their blood sugar in control. Medication needs often change over time, so it’s important for everyone with diabetes to have medical care.

Symptoms of Type 2 diabetes often develop gradually. They include persistent fatigue, increased thirst and urination, blurry vision, frequent infections, slow healing and unintended weight loss. Risk factors for developing the disease include being overweight, storing excess fat mainly in the abdominal region, a family history of diabetes, inactivity and being over the age of 45. These last two factors are associated with a drop in lean muscle mass, which some researchers think may play a role.

Type 2 diabetes used to be seen most often in middle-aged adults. Unfortunately, in recent years it has increasingly been seen in young adults, adolescents and even children. If you suspect you have developed the disease, it’s important to see your doctor. Diagnosis is usually via a blood test. Treatment includes weight loss, changes to diet, exercise, blood sugar monitoring and, possibly, the use of medications or insulin.

(Send your questions to askthedoctors@mednet.ucla.edu. Owing to the volume of mail, personal replies cannot be provided.)