(CNN) -- Half of all Americans may be diabetic or prediabetic by 2020, a report from an insurance company warned Tuesday. That's an even bleaker projection than the Centers for Disease Control's recent estimate that one in three Americans would have diabetes by 2050.
Current rates show that about one in 10 Americans has diabetes, and the risks increase with age. Even children and teenagers are developing type 2 diabetes.
A report released this week by UnitedHealth Group showed that treating diabetes will also take up almost 10 percent of all health care spending. That 10-year price tag: $3.35 trillion.
Despite such gloomy projections, diabetes is not inevitable. Practical health changes can lower risk of type 2 diabetes, which occurs more commonly with aging and sedentary lifestyles. Type 1 diabetes is an autoimmune disease unrelated to aging or lifestyle.
While diabetes projections sound scary, "the numbers are getting people aware about the risk factors and thinking about them," said Beth Mayer-Davis, the president-elect of health care and education at the American Diabetes Association.
4 keys to managing diabetes: How do you rate?
Genetics, race and family history affect a person's chances of developing diabetes, but you can take steps to lower your risk of type 2 diabetes.
The most important thing: Lose weight
"The heavier we are, the tougher it is for our body," said Dr. Armand Krikorian, who specializes in endocrinology and diabetes at University Hospitals Case Medical Center in Ohio. "It has to make more insulin to keep the blood sugar under control."
Insulin, a substance created in the pancreas, moves glucose from the bloodstream into muscles, fat and liver cells. But in type 2 diabetes, the body doesn't respond to insulin, and glucose builds up in the blood.
Overweight people are more likely to develop diabetes because the fat interferes with the body's ability to use insulin.
Krikorian used this analogy: "You have a horse; you're asking it to run all the time. You're whipping it to run faster all the time, and it can't do it any more. The heavier I am, the more I'm asking my pancreas to make more insulin to keep sugars under control. Over the long term, it's exhausting the pancreas, and that's when diabetes sets in."
About half of overweight or obese people have prediabetes or diabetes, said Mayer-Davis, a epidemiologist specializing in diabetes.
Exercise burns energy and helps the body manage the glucose.
"It doesn't have to be running a marathon," Krikorian said. "Any amount of regular scheduled activity, the more, the better. A half an hour of daily activity is a good start."
Studies have found that 7 to 10 percent body weight loss can greatly help with diabetes prevention.
"We're not saying you have to become fashion magazine models," Mayer-Davis said. "If you're 300 pounds, a 10 percent weight loss, that's 30 pounds."
Watch your food's quality and quantity
It's the mantra of public health: Eat your fruits and veggies.
Toby Smithson, a registered dietitian and a spokeswoman for the American Dietetic Association, also suggests eating nutrient-dense foods such as lean protein, whole grains and low-fat dairy.
"All foods can fit into a healthy diet," she said. "The key is the portion and to make sure it is balanced throughout the day."
Although everyone has different dietary needs, a general guideline is two servings of low-fat or non-fat milk or yogurt, two to five servings of fruit; four to 12 servings of grains, beans or starchy vegetables; three to five servings of non-starchy vegetables; and two to three servings of lean protein (5 to 9 ounces) each day.
Studies show that a diet with lower fat reduces diabetes risk. But it doesn't matter which weight-loss plan a person chooses, as long as it reduces calories, Mayer-Davis said.
People know that they should eat right and exercise but struggle to execute.
Studies show that people in a group lifestyle intervention could reduce their diabetes risks. One of the best-known programs came from the CDC, the YMCA and United Health Group. The Diabetes Prevention Program assigns a lifestyle coach to participants who are at high risk of developing diabetes. The group learns about ways to eat healthier, exercise and make lifestyle improvements. They meet monthly.
"The group dynamic can share the things that worked for them, their successes and struggles, that can be helpful to people," Mayer-Davis said.
If support groups aren't available, find supportive friends, partners or people who will encourage you, she said.
Act now, before you're diabetic
"If you don't want to have diabetes and end up monitoring blood sugar, taking pills and insulin, this is the time to act," Krikorian said. "Stay active, lose weight and prevent getting the diabetes. It is preventable."
In general, about a third of the people who are in the category of prediabetes develop diabetes after three to five years.
"Having prediabetes doesn't mean you're going to have diabetes," Krikorian said. "Unfortunately, a lot of time, we don't act till it's too late. We procrastinate. When we don't feel imminent danger, we tend to be lax."
Prediabetes means you've tested higher than the normal levels on one of the three tests: A1C, fasting plasma glucose or oral glucose tolerance.
That means levels above 5.7 percent on an A1C test, 100 milligrams per deciliter on the fasting plasma glucose test and 140 milligrams per deciliter on the oral glucose tolerance test. The American Diabetes Association has more on prediabetes.
Diabetes can be controlled
Diabetes doesn't necessarily mean amputations, blindness or dialysis. Those are worst-case complications.
Many people control their diabetes through proper diet and exercise, and thrive without medication.
Although they're not "cured," they're able to control the disease.
"The positive message is that the complications are preventable," Krikorian said. "It doesn't mean they're doomed."