Type 2 diabetes, the most common type of diabetes, is a disease that occurs when your blood glucose, also called blood sugar, is too high. Blood glucose is your main source of energy and comes mainly from the food you eat. Insulin, a hormone made by the pancreas, helps glucose get into your cells to be used for energy. In type 2 diabetes, your body doesn’t make enough insulin or doesn’t use insulin well. Too much glucose then stays in your blood, and not enough reaches your cells.
The good news is that you can take steps to prevent or delay the development of type 2 diabetes.
Who is more likely to develop type 2 diabetes?
You can develop type 2 diabetes at any age, even during childhood. However, type 2 diabetes occurs most often in middle-aged and older people. You are more likely to develop type 2 diabetes if you are age 45 or older, have a family history of diabetes, or are overweight or obese.
As in type 1 diabetes, certain genes may make you more likely to develop type 2 diabetes. The disease tends to run in families and occurs more often in these racial/ethnic groups:
- African Americans
- Alaska Natives
- American Indians
- Asian Americans
- Native Hawaiians
- Pacific Islanders
Genes also can increase the risk of type 2 diabetes by increasing a person’s tendency to become overweight or obese.
Additional Risk factors
You are more likely to develop type 2 diabetes if you
- are overweight or obese
- are age 45 or older
- have a family history of diabetes
- are African American, Alaska Native, American Indian, Asian American, Hispanic/Latino, Native Hawaiian, or Pacific Islander
- have high blood pressure
- have a low level of HDL (“good”) cholesterol, or a high level of triglycerides
- have a history of gestational diabetes or gave birth to a baby weighing 9 pounds or more
- are not physically active
- have a history of heart disease or stroke
- have depression
- have polycystic ovary syndrome, also called PCOS
- have acanthosis nigricans—dark, thick, and velvety skin around your neck or armpits
What are the symptoms of diabetes?
Symptoms of diabetes include
- increased thirst and urination
- increased hunger
- feeling tired
- blurred vision
- numbness or tingling in the feet or hands
- sores that do not heal
- unexplained weight loss
Symptoms of type 2 diabetes often develop slowly—over the course of several years—and can be so mild that you might not even notice them. Many people have no symptoms. Some people do not find out they have the disease until they have diabetes-related health problems, such as blurred vision or heart disease.
What causes type 2 diabetes?
Type 2 diabetes is caused by several factors, including
- overweight and obesity
- not being physically active
- insulin resistance
Overweight, obesity, and physical inactivity
You are more likely to develop type 2 diabetes if you are not physically active and are overweight or obese. Extra weight sometimes causes insulin resistance and is common in people with type 2 diabetes. The location of body fat also makes a difference. Extra belly fat is linked to insulin resistance, type 2 diabetes, and heart and blood vessel disease.
Type 2 diabetes usually begins with insulin resistance, a condition in which muscle, liver, and fat cells do not use insulin well. As a result, your body needs more insulin to help glucose enter cells. At first, the pancreas makes more insulin to keep up with the added demand. Over time, the pancreas can’t make enough insulin, and blood glucose levels rise.
What causes gestational diabetes?
Scientists believe gestational diabetes, a type of diabetes that develops during pregnancy, is caused by the hormonal changes of pregnancy along with genetic and lifestyle factors.
Hormones produced by the placenta contribute to insulin resistance, which occurs in all women during late pregnancy. Most pregnant women can produce enough insulin to overcome insulin resistance, but some cannot. Gestational diabetes occurs when the pancreas can’t make enough insulin.
As with type 2 diabetes, extra weight is linked to gestational diabetes. Women who are overweight or obese may already have insulin resistance when they become pregnant. Gaining too much weight during pregnancy may also be a factor.
- Monogenic diabetes is caused by mutations, or changes, in a single gene. These changes are usually passed through families, but sometimes the gene mutation happens on its own. Most of these gene mutations cause diabetes by making the pancreas less able to make insulin. The most common types of monogenic diabetes are neonatal diabetes and maturity-onset diabetes of the young (MODY). Neonatal diabetes occurs in the first 6 months of life. Doctors usually diagnose MODY during adolescence or early adulthood, but sometimes the disease is not diagnosed until later in life.
- Cystic fibrosis produces thick mucus that causes scarring in the pancreas. This scarring can prevent the pancreas from making enough insulin.
- Hemochromatosis causes the body to store too much iron. If the disease is not treated, iron can build up in and damage the pancreas and other organs.
Some hormonal diseases cause the body to produce too much of certain hormones, which sometimes cause insulin resistance and diabetes.
- Cushing’s syndrome occurs when the body produces too much cortisol—often called the “stress hormone.”
- Acromegaly occurs when the body produces too much growth hormone.
- Hyperthyroidism occurs when the thyroid gland produces too much thyroid hormone.
Damage to or removal of the pancreas
Pancreatitis, pancreatic cancer, and trauma can all harm the beta cells or make them less able to produce insulin, resulting in diabetes. If the damaged pancreas is removed, diabetes will occur due to the loss of the beta cells.
Sometimes certain medicines can harm beta cells or disrupt the way insulin works. These include
- niacin, a type of vitamin B3
- certain types of diuretics, also called water pills
- anti-seizure drugs
- psychiatric drugs
- drugs to treat human immunodeficiency virus (HIV)
- pentamidine, a drug used to treat a type of pneumonia
- glucocorticoids—medicines used to treat inflammatory illnesses such as rheumatoid arthritis, asthma, lupus, and ulcerative colitis
- anti-rejection medicines, used to help stop the body from rejecting a transplanted organ
Statins, which are medicines to reduce LDL (“bad”) cholesterol levels, can slightly increase the chance that you’ll develop diabetes. However, statins help protect you from heart disease and stroke. For this reason, the strong benefits of taking statins outweigh the small chance that you could develop diabetes.
If you take any of these medicines and are concerned about their side effects, talk with your doctor.
How do health care professionals diagnose type 2 diabetes?
Your health care professional can diagnose type 2 diabetes based on blood tests. You can learn more about testing for diabetes here.
How can I manage my type 2 diabetes?
Managing your blood glucose, blood pressure, and cholesterol, and quitting smoking if you smoke, are important ways to manage your type 2 diabetes. Lifestyle changes that include planning healthy meals, limiting calories if you are overweight, and being physically active are also part of managing your diabetes. So is taking any prescribed medicines. Work with your health care team to create a diabetes care plan that works for you.
What medicines do I need to treat my type 2 diabetes?
Along with following your diabetes care plan, you may need diabetes medicines, which may include pills or medicines you inject under your skin, such as insulin. Over time, you may need more than one diabetes medicine to manage your blood glucose. Even if you don’t take insulin, you may need it at special times, such as during pregnancy or if you are in the hospital. You also may need medicines for high blood pressure, high cholesterol, or other conditions.
Learn more about medicines, insulin, and other diabetes treatments.
What health problems can people with diabetes develop?
Following a good diabetes care plan can help protect against many diabetes-related health problems. However, if not managed, diabetes can lead to problems such as
- heart disease and stroke
- nerve damage
- kidney disease
- foot problems
- eye disease
- gum disease and other dental problems
- sexual and bladder problems
Many people with type 2 diabetes also have nonalcoholic fatty liver disease (NAFLD). Losing weight if you are overweight or obese can improve NAFLD. Diabetes is also linked to other health problems such as sleep apnea, depression, some types of cancer, and dementia
How can I lower my chances of developing type 2 diabetes?
Research such as the Diabetes Prevention Program [External link], sponsored by the National Institutes of Health, has shown that you can take steps to reduce your chances of developing type 2 diabetes if you have risk factors for the disease. Here are some things you can do to lower your risk:
- Lose weight if you are overweight, and keep it off. You may be able to prevent or delay diabetes by losing 5 to 7 percent of your current weight. For instance, if you weigh 200 pounds, your goal would be to lose about 10 to 14 pounds.
- Move more. Get at least 30 minutes of physical activity, such as walking, at least 5 days a week. If you have not been active, talk with your health care professional about which activities are best. Start slowly and build up to your goal.
- Eat healthy foods. Eat smaller portions to reduce the amount of calories you eat each day and help you lose weight. Choosing foods with less fat is another way to reduce calories. Drink water instead of sweetened beverages.
Ask your health care team what other changes you can make to prevent or delay type 2 diabetes.
This article has been reproduced in part from the National Institute of Diabetes and Digestive and Kidney Diseases. Visit their site for more detailed information on assistance with Diabetes within the U.S.