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T ype 2 diabetes is both common and on the rise. The disease occurs when the body is unable to use insulin to adequately control levels of blood glucose, the energy from food that fuels cells and organs. It affects more than 30 million Americans. About 12 million are older than 65, according to a Centers for Disease Control and Prevention report released last year.

Just as alarming: About 84 million adults—half of them older than 65—have prediabetes, glucose levels high enough to put them in danger of developing diabetes.

And nearly a quarter of people who have type 2 diabetes and many more with prediabetes don't realize it.

The consequences of untreated type 2 diabetes can include blindness, severe nerve damage, kidney failure, heart disease, and stroke. It's the seventh leading cause of death in the U.S.

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But there's also good news. Relatively simple steps, such as losing weight, eating a healthful diet, getting physical activity, monitoring your health, and, when necessary, taking medication, can slow the course of the disease and improve your quality of life.

Here's what recent research has uncovered on the best ways to reduce your risks and treat type 2 diabetes if you have it.

Use the Power of Lifestyle

Doctors used to think that if you received a diagnosis of type 2 diabetes, you'd have the condition for life. But now ­research shows that's not the case.

"Many times, type 2 diabetes can be partially or completely reversed by getting down to a normal weight," says Michael Hochman, M.D., M.P.H., an associate professor of clinical medicine at the Keck School of Medicine at the University of Southern California in Los Angeles and director of the USC Gehr Center for Health Systems Science.

A study published in 2017 in The Lancet, for instance, found that about half of people with type 2 diabetes who underwent an intensive weight-management program went into complete remission.

The same goes for prediabetes. "The majority of cases come from being overweight or obese, so simply losing weight can go a long way in preventing you from progressing to actual diabetes," says David Lam, M.D., medical director of the Mount Sinai Clinical Diabetes Institute in New York City.

Case in point: People with prediabetes who lose around 7 percent of their body weight by consuming less fat and fewer calories and exercising for 150 minutes a week have a 58 percent lower risk of full-blown diabetes, according to the landmark Diabetes Prevention Program study.

Though it's more difficult to reverse a diabetes diagnosis if you've had it for several years, lifestyle habits can be potent enough to allow you to cut back on medications, even if you can't eliminate them entirely, Hochman says. Here, several takeaways:

Eat right. Following a Mediterranean diet—rich in healthy fats, whole grains, beans, nuts, and fruits and vegetables, and low in processed meats, sugars, and refined carbohydrates—can help prevent or even reverse type 2 diabetes, according to a 2016 Tufts University study published in the journal PLOS Medicine.

In another study, researchers at the Harvard T.H. Chan School of Public Health found that eating a healthy plant-based diet reduced the risk of devel­op­ing type 2 diabetes by 20 percent.

"The key is a diet rich in minimally processed plant foods and high levels of healthy fats found in foods like nuts, olive oil, and fatty fish like salmon," says Dariush Mozaffarian, M.D., Dr.P.H., a cardiologist and dean of the Friedman School of Nutrition Science and Policy at Tufts University in Boston.

Though a serving (3 to 4 ounces) of lean, unprocessed chicken or meat once or twice a week is fine, think of it "as a side and not as the core of your plate," Mozaffarian says. Red meat is high in heme iron; eating too much is associated with an increased risk of type 2 diabetes.

Be wise about carbs. Carbohydrates—starches, sugars, and fiber—are the nutrients that have the biggest impact on blood glucose levels. But people with diabetes (or those at risk for it) don't have to shun them.

Nor do you have to obsessively track the grams of carbohydrates in your diet, which some experts recommend for people with diabetes, especially if they use insulin. "It can be overwhelming, especially for older patients," says David Lam, M.D., of the Mount Sinai Clinical Diabetes Institute.

In addition, certain carbs are rich in fiber, which helps your body metabolize blood glucose better, says Mozaffarian. Minimize your intake of refined carbs, such as white bread and white rice, and added sugars, but note that the following higher-carb foods can be part of a healthy diet for people with diabetes.

Beets, carrots, sweet potatoes, and winter squash are higher in sugars than green vegetables but are still considered relatively low-carb foods. Fruit is rich in nutrients and fiber, and studies show no link to type 2 diabetes. Stick to fresh or frozen fruit, or canned fruit in water. Juice can raise blood glucose levels.

Many studies show a strong link between whole grains (such as buckwheat, bulgur, oatmeal, and quinoa) and a lower type 2 diabetes risk. The majority of the grains you eat should be in whole form. When it comes to potatoes, a few servings a week may be okay, but frequent consumption could raise type 2 diabetes risk. Mashed or boiled are far less likely to do so than french fries.

Move as much as possible. Regular exercise—150 weekly minutes of moderate to vigorous activity, such as brisk walking—can help you manage type 2 diabetes.

Even if you aren't overweight, exercise is important. A 2017 University of Florida study found that being sedentary is linked to higher blood glucose, even for those at a healthy weight.

"We think that sitting for prolonged periods of time affects glucose and fat metabolism, increasing risk for type 2 diabetes," says Betul Hatipoglu, M.D., an endocrinologist at the Cleveland Clinic.

To break up sedentary time, the American Diabetes Association recommends at least 3 minutes of light activity, such as walking, leg extensions, or overhead arm stretches, every 30 minutes.

Get enough sleep and reduce stress. When you're stressed, your body ramps up production of the hormone cortisol, which increases your body's blood glucose levels, Hatipoglu says. The same thing happens when you get too little sleep.

What's more, a study of almost 5,000 Japanese adults with type 2 diabetes, published in the journal Diabetes Care, found that those who got between 6½ and 7½ hours of sleep a night had slightly lower HbA1c levels—a measurement of average blood glucose levels over three months—than those whose levels were less than 5 or more than 8. ­

Another 2015 study published in Diabetes Care found that people who got ­between 7 and 8 hours of shut-eye a night had the lowest risk of developing type 2 diabetes.

Get Blood Sugar Goals Right

In the past, people with type 2 diabetes were advised to aim for HbA1c levels that were very close to those for people without diabetes, lower than 7 percent or even under 6.5.

But recently that thinking changed. Guidelines released last spring from the American College of Physicians (ACP) recommend that most aim for HbA1c levels between 7 and 8 percent.

Most of the evidence presented in the new guidelines focused on five major trials. These found that people who got their HbA1c levels below 6.5 had a higher risk of death from heart disease than those who were between 7 and 8.

One of those trials, for example, found that people on intensive drug treatments to get their HbA1c below 6 were 22 percent more likely to die from any cause, 35 percent more likely to die from heart disease, and nearly twice as likely to gain more than 22 pounds.

When blood sugar is too low, your heart rate increases and your blood pressure level may change. "The association ­between intense treatment of type 2 diabetes and cardiovascular mortality may be explained by the hazardous ­effects of low blood sugar," says Jack Ende, M.D., the ACP's immediate past president.

But some doctors might feel pressure to get the numbers down because they may receive financial incentives for helping patients meet lower targets.

What's likely is that not everyone with type 2 diabetes should strive for the same HbA1c. "Any diabetes specialist will tell you that one size never fits all," Hatipoglu says. "Every single patient with type 2 diabetes has a different background and different disease stage, and as a result, treatment needs to be individualized."

In general, if you have type 2 diabetes and you're younger than 65 and in good health, it's reasonable to aim for an HbA1c between 6.5 and 7 percent.

But if you're slightly higher than the 7 percent mark—say, at 7.1 or 7.2—there's no reason to push yourself to go any lower.

For older adults with conditions such as heart and lung disease, an HbA1c ­between 7 and 8 is fine.

This is low enough to prevent high blood sugar symptoms such as increased urination, dehydration, and unwanted weight loss without triggering hypoglycemia. (Regard­less of age, if you dip below 6.5 percent, talk to your doctor about your therapy regimen.)

Be Savvy About Medications

If your doctor recommends medication to treat type 2 diabetes, your first-line therapy should almost always be metformin (Glucophage, Glumetza, and generic). This increases the response to your own insulin and inhibits glucose production by the liver.

"I've been seeing patients initially ­being put on newer diabetes medications, but these drugs are not as well-studied as metformin and may not be as safe and effective, and they are much more expensive since they are not yet available as generics," Hochman says. These ­include exenatide (Byetta) and semaglutide (Ozempic).

Consumer Reports' own analysis of evidence has concluded that metformin lowers HbA1c as much as or more than more costly diabetes drugs, doesn't lead to weight gain, and is less likely to trigger hypoglycemia than medications such as nateglinide (Starlix and generic) and ­repaglinide (Prandin and generic).

The exception: In people with moderate to severe kidney disease, metformin has been associated with a potentially fatal buildup of lactic acid in the blood.

If you're using metformin to treat type 2 diabetes and within three to six months your HbA1c level isn't below 8 percent (or if to begin with your HbA1c is higher than 9.5), you'll need a second drug, Hatipoglu says.

CR experts recommend a sulfonylurea, either glipizide (Glucotrol, Glucotrol XL, and generic) or glimepiride (Amaryl and generic).

These drugs, which increase insu­lin secretion by the pancreas, have a lower risk of gastrointestinal side effects than metformin but can cause a weight gain of 5 to 10 pounds.

And if these don't work, Lipman says, it's reasonable to consider yet another class of drugs, such as gliptins—like ­sitagliptin (Januvia) and empagliflozin (Jardiance).

These oral medications are less likely to cause weight gain and other side effects, but because they're unavailable as generics, they can be very expensive.

Keep Up With Essential Health Checks

Type 2 diabetes can harm many of your body's organs and systems, and in the early stages, this can occur without your even realizing it. So in addition to monitoring blood glucose, keep an eye on the following:

Your eyes. Even well-controlled diabetes can damage the small blood vessels in your retina or the back of your eyes. Diabetes also hikes the risk of glaucoma and macular degeneration. Untreated, all can lead to blindness, so get a comprehensive eye exam every year.

Your feet. As a result of impaired nerve function and blood flow to the feet, diabetes puts you at higher risk of foot complications such as infection. Have your doctor or a podiatrist check at least twice a year for symptoms such as a loss of sensation and tingling.

Your heart. Type 2 diabetes can double or quadruple heart disease and stroke risks. Ask your doctor how often to have blood pressure and cholesterol checks, and aim for a blood pressure level close to 120/80 mmHg and LDL (bad) cholesterol level lower than 100 mg/dl.

Your teeth. More than 20 percent of those with type 2 diabetes have gum disease, too. Having gum disease may make it even more difficult to control your blood glucose, and it could contribute to worsening type 2 diabetes. So be sure to see your dentist twice a year.

Your kidneys. Chronically high glucose levels can harm the kidneys' ability to remove waste products from blood. Your doctor should do two annual tests: one to check urine for albumin (a sign of kidney damage) and a blood test, called GFR, to see how well your kidneys filter blood.