Tom Hanks has Type 2 diabetes, he shared on "The Late Show with David Letterman" on Monday night.

The 57-year-old actor told Letterman that he has been dealing with high blood sugar since he was 36, but he has now been diagnosed with Type 2 diabetes.

"My doctor said, 'Look, if you can weigh as much as you weighed in high school, you will essentially be completely healthy and not have Type 2 diabetes,'" Hanks said on the show. "And I said to her, 'Well, I'm gonna have Type 2 diabetes.'"

Nearly 26 million people in the U.S., including kids and adults, have Type 2 diabetes, a condition where the body is unable to produce enough insulin to maintain normal blood sugar levels, or becomes resistant to insulin's effects.

Exercising, eating right, monitoring blood sugar levels and taking medications can all help to keep blood sugar at normal levels, according to the Mayo Clinic. It's important to maintain normal blood sugar levels because complications, though slow-developing, can lead to nerve damage, heart disease, kidney damage, osteoporosis and even Alzheimer's.

Type 2 diabetes risk goes up with age, particularly among people age 45 and older. Weight gain is a huge risk factor, as is physical inactivity, having a family history of the condition, having other high biomarkers of health (such as blood pressure or cholesterol), and being of African American, Alaska Native, Asian American, American Indian or Latino race, the National Institute of Diabetes and Digestive and Kidney Diseases reported.

Dr. Holly Phillips, a medical contributor to CBS News, also explained that weight fluctuations might have contributed to Hanks's development of Type 2 diabetes. (Hanks lost more than 50 pounds when for his role in "Castaway," and gained 30 pounds for his role in "A League Of Their Own," CBS News reported.)

"He'll have to watch what he eats very closely, he'll need to exercise regularly but there's no reason he can't live a perfectly normal life," Phillips told CBS News. "In dramatic weight gain and dramatic weight loss, the equilibrium of the body is just completely off. So that might predispose him to developing Type 2 diabetes later."

Also on HuffPost:

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  • Halle Berry

    The actress was diagnosed with diabetes in 1989 after she became ill on the set of a short-lived television show, "Living Dolls" and slipped into a diabetic coma for a reported seven days. Her doctors <a href="http://abcnews.go.com/Health/story?id=3822870&page=1/=#.TxbsmWPOzDU" target="_hplink">initially misdiagnosed her as having Type 1 diabetes</a>, an incurable, autoimmune condition in which the pancreas does not produce insulin. In truth, the actress has Type 2, which is much more related to lifestyle. She claims to have <a href="http://www.contactmusic.com/news/berry-beating-diabetes_1048407" target="_hplink">regulated her insulin levels with diet alone</a>. "Because she is thin and healthy, her physician initially probably thought that she had Type 1, though in African-Americans there is an increased risk for Type 2. The diagnosis wasn't necessarily a bait and switch, but it might have just been a matter of her physicians getting a better handle on the kind of diabetes she had," Dr. Ronald Kahn, director of the Joslin Diabetes Center at Harvard, told ABC News.

  • Randy Jackson

    The musician and American Idol judge was first diagnosed with Type 2 diabetes in 1999 when he was morbidly obese, tipping the scales at over 350 pounds. "I thought I had a cold and started taking cold medicine," <a href="http://forecast.diabetes.org/magazine/features/randy-jackson" target="_hplink">Jackson told the American Diabetes Association's <em>Diabetes Forecast</em> Magazine</a>. "I was tired, lethargic, very thirsty. Of course, I didn't take into consideration that a history of type 2 diabetes ran in my family, because you always think that happens to somebody else, not to you." He credits the diagnosis with kickstarting his dedication to fitness and health: he got gastric bypass surgery, changed his diet and started exercising. Though he continues to check his blood sugar daily, he's been monitoring his insulin without medication for over five years. Drug-free management and even diagnosis reversals are not as difficult or uncommon as previously thought, <a href="http://www.huffingtonpost.com/dr-mark-hyman/reverse-diabetes_b_918539.html" target="_hplink">reported Dr. Mark Hyman in The Huffington Post</a>: <blockquote>With focused, strategic, scientifically based nutritional intervention, combined with exercise, stress management and sugar and insulin balancing nutritional supplements, many of my patients completely reverse their diabetes. And the side effects -- more energy, better sleep, improved sexual function and weight loss -- are all good.</blockquote>

  • Patti LaBelle

    The self-proclaimed "divabetic" was diagnosed with Type 2 diabetes in the mid-90s after collapsing onstage. She's since made major changes to her diet and upped her exercise. She credits the latter with saving her from some of diabetes' more extreme consequences, which can include feet and leg amputations and blindness. For LaBelle, managing the condition is especially meaningful, given her family's history. Her mother, grandmother, aunt and uncle all had the condition, <a href="http://www.people.com/people/package/article/0,,20167126_20248033,00.html" target="_hplink">according to a profile in <em>People</em> Magazine</a>. Her mother eventually had both legs amputated and her uncle lost his eyesight. "So when the doctor told me I was a diabetic, I was like, 'No, no, no,'" <a href="http://www.people.com/people/package/article/0,,20167126_20248033,00.html" target="_hplink">she told <em>People</em></a>, adding: "I feel great now."

  • Mike Huckabee

    The Former governor of Arkansas and Republican presidential nominee famously lost more than 100 pounds in just 10 months. And while heart health was his main concern, the FOX News commentator was also able to reverse the Type 2 diabetes diagnosis he received in his mid 40s through a combination of portion control, eliminating fried foods and exercising regularly. Both of his parents and two grandparents all had diabetes and, at more than 300 pounds, it wasn't surprising that he'd developed the disease. His environment didn't help: Type 2 diabetes increased 35 percent in Arkansas between 1993 and 2002, <a href="http://www.healthy.arkansas.gov/programsServices/epidemiology/ChronicDisease/Documents/publications/diabetes_in_arkansas.pdf" target="_hplink">according to CDC data</a>. With over 240,000 diabetic residents, Huckabee was truly a reflection of his constituents. Since his reversal, Huckabee has dedicated himself to trying to help others -- he even <a href="http://www.amazon.com/Quit-Digging-Your-Grave-Knife/dp/0446578061" target="_hplink">wrote a 12-step program entitled <em>Quit Digging Your Grave with a Knife and Fork</em></a>.

  • Larry King

    The former CNN anchor and talk show host was diagnosed with diabetes in 1995, though he has generally remained private about it. In an <a href="http://forecast.diabetes.org/magazine/features/larry-king-talks" target="_hplink">interview with the American Diabetes Association's <em>Diabetes Forecast</em> Magazine</a>, King says the diabetes was a surprise: he had no symptoms and, following heart surgery, he'd taken up regular exercise and healthful eating habits. "I don't know what diabetes feels like. I know whenever I go to the doctor, they check my feet," he said. "I have my eyes tested once a year, and they report that to my diabetic doctor."

  • Sherri Shepherd

    The actress and co-host of "The View" credits her Type 2 diabetes diagnosis with motivating her to lose excess weight. "My mom died of diabetes complications when she was 41," <a href="http://www.fitnessmagazine.com/workout/real-plans/stay-fit/sherri-shepherd/" target="_hplink">Shepherd told <em>Fitness</em> Magazine</a>. "When I was 40, my doctor told me, 'I don't know when you're going to have a stroke, but it's going to happen.'" After that conversation, Shepherd worked hard on her fitness and diet program and lost a reported 10 inches off her waist in just three months.

  • Paul Sorvino

    For a long time after his diagnosis, the actor and director <a href="http://www.usatoday.com/yourlife/health/medical/diabetes/2010-11-30-sorvinoonline30_ST_N.htm" target="_hplink">Paul Sorvino continued to eat</a> as if he did not have Type 2 diabetes. His blood sugar went virtually unregulated, until his daughter, the actress Mira Sorvino intervened. Now, the family eats low carb pasta and skips dessert in favor of going for walks together. "There's an Italian expression ... 'Not every ill comes to destroy you,'" explained Sorvino in a video interview with his daughter for <em><a href="http://www.usatoday.com/yourlife/health/medical/diabetes/2010-11-30-sorvinoonline30_ST_N.htm" target="_hplink">USA Today.</a> "One of the things that this does for you is forces you to take care of yourself."

  • Dick Clark

    The iconic TV presenter was diagnosed with Type 2 diabetes in the early 90s, but only went public with his condition in 2004 as part of his effort to educate people about the links between diabetes and cardiovascular health. Unfortunately, that same year, he suffered from a stroke. Since that time, having recovered his speech and mobility, Clark -- who is commonly known as "America's oldest teenager" -- has continued to make appearances in support of diabetes awareness.

  • Billie Jean King

    Tennis legend King wants people to know that even fit, active people can get Type 2 diabetes. "Anyone can develop diabetes, even an athlete," <a href="http://health.msn.com/health-topics/diabetes/tennis-legend-billie-jean-king-in-match-with-type-2-diabetes" target="_hplink">she told Health.com</a>, adding that her behavior wasn't always healthy. "I have an eating disorder; I was a binge eater. I don't binge eat anymore, but for about 10 years, I was being very cruel to my poor little pancreas." Along with continued regular exercise and a healthy diet, King credits getting enough sleep with helping her manage the disease, by decreasing her appetite. She also takes metformin, a medication that helps manage blood sugar.