Early symptoms of type 2 diabetes can be easy to miss

Type 2 diabetes is a sneaky devil. Early on, the warning signs can be hard to spot and people sometimes chalk them up to stress or fatigue, and shrug them off. But screening tests and understanding your risk can help people spot diabetes sooner and get the treatment they need, say experts.

"The main thing about early diabetes is that you can have abnormal blood sugar for quite some time and be fairly asymptomatic," Dr. Susan Spratt, an endocrinologist and assistant professor of medicine at Duke University School of Medicine, told CBS News.

More than 29 million Americans have diabetes - that's nearly 1 out of 10 U.S. adults - and according to the Centers for Disease Control and Prevention, more than a quarter of them are undiagnosed. Millions of others are considered at high risk for developing diabetes.

Spratt said some people with undiagnosed type 2 diabetes may experience dry mouth, excessive thirst, and they may urinate more frequently. Blurry vision can occur, too.

Cuts and bruises may be slow to heal and you may feel tingling, pain, or numbness in your hands and feet, according to the American Diabetes Association. Feeling hungry, even after eating, and experiencing extreme fatigue are symptoms, as well.

What's happening in the body when type 2 diabetes is lurking? The condition develops when the body becomes resistant to insulin or when the pancreas stops producing enough insulin. It's not clear why this happens, but genetics and factors such as weight and a sedentary lifestyle can play into the equation, Mayo Clinic experts say.

The body needs insulin to survive - it's secreted into the bloodstream via the pancreas. When insulin circulates, it enables sugar to enter cells and lowers the amount of sugar in the bloodstream.

With type 2 diabetes, instead of insulin moving into your body's cells, sugar builds up in the bloodstream; the insulin-making beta cells in the pancreas produce more insulin but eventually, Mayo experts say, these cells become impaired and can't produce enough insulin to meet the body's requirements.

Doctors say it's pivotal to identify type 2 diabetes sooner rather than later and get it treated. Over time, people with untreated diabetes can develop heart, vision, nerve, and kidney problems, among other health complications. Type 2 diabetes may also increase the risk for Alzheimer's disease, some studies suggest.

The International Diabetes Federation is aiming to raise awareness of the risk and promote education about diabetes ahead of World Diabetes Day this Saturday.

Spratt told CBS News that sometimes patients with untreated diabetes will also describe symptoms of low blood sugar.

"Symptoms may include feeling sweaty, jitters, a sense of doom, light-headedness. If someone doesn't have a diagnosis of diabetes and is feeling these things, they should get screened," said Spratt.

There are several ways to do that, she explained:

• A1C test. Also called a glycated hemoglobin, this blood test lets you know your average blood sugar level for the past two to three months. An A1C level that falls between 5.7 and 6.4 percent is considered prediabetes, and means you're at risk for the condition. An A1C of 6.5 percent or above indicates you have diabetes. Anything under 5.7 percent is a normal level.

• Fasting blood sugar test. For this test, a blood sample is taken after you've fasted (nothing to eat or drink for eight hours) overnight. A fasting blood sugar level of 100 to 125 milligrams per deciliter (mg/dL) falls into the prediabetes range. A level of 126 mg/dL or above indicates diabetes.

• Oral glucose tolerance test. This two-hour test also requires overnight fasting, followed by drinking a sugary beverage and periodic blood sugar level tests over the next couple of hours. A blood sugar level below 140 mg/dL is normal and anything over 200 mg/dL after the two-hour test points to diabetes. Readings in between suggest prediabetes.

You can ask your doctor for a screening, or some health fairs offer diabetes tests.

"We initially decided to do [A1C] diabetes screening and we found we were screening all these healthy people because that's often who attends health fairs. It was a waste of money so we tailored our test to those who scored higher on a risk assessment. If they were five or higher we did an A1C test," said Spratt, who noted that through local health fairs, they're identifying a lot of people with prediabetes.

The American Diabetes Association also offers an online risk assessment tool for diabetes.

Jeannette Jordan, a diabetes educator and registered dietitian from Charleston, South Carolina, who is also a consultant to insulin-maker Novo Nordisk, said a lot of people aren't aware of their risk for diabetes.

She said being over age 45, especially if you are overweight, can raise your risk. African Americans, Hispanic Americans, Native Indians, Asian Americans, and Pacific Islanders are also at higher risk for diabetes. Having a parent, brother, or sister can up your chances of getting the disease, too, she said.

Jordan said many people can have diabetes for years without knowing it, but understanding your risk factors can help identify the condition sooner.

"Many people have several of these risk factors," said Jordan.

But that doesn't mean people with risk factors are doomed to develop the illness. The American Diabetes Association says research shows you can reduce your risk for type 2 diabetes by 58 percent if you:

• Lose seven percent of your body weight (or 15 pounds if you weigh 200 pounds).
• Exercise moderately, such as brisk walking, for 30 minutes a day, five days a week.

Even if you can't reach your ideal body weight, losing 10 to 15 pounds can still help.

Harvard's T.H. Chan School of Public Health also says there's convincing evidence that eating a diet rich in whole grains can protect against diabetes, while diets heavy on refined carbohydrates may increased risk.

Finally, the Harvard experts recommend turning off the TV, since research has shown that every two hours you spend watching TV instead of doing something more active increases your chances of developing diabetes by 20 percent.