Skip to main content

Type 2 diabetes

Medically reviewed by Drugs.com. Last updated on Mar 14, 2023.

Overview

Type 2 diabetes is a condition that happens because of a problem in the way the body regulates and uses sugar as a fuel. That sugar also is called glucose. This long-term condition results in too much sugar circulating in the blood. Eventually, high blood sugar levels can lead to disorders of the circulatory, nervous and immune systems.

In type 2 diabetes, there are primarily two problems. The pancreas does not produce enough insulin — a hormone that regulates the movement of sugar into the cells. And cells respond poorly to insulin and take in less sugar.

Type 2 diabetes used to be known as adult-onset diabetes, but both type 1 and type 2 diabetes can begin during childhood and adulthood. Type 2 is more common in older adults. But the increase in the number of children with obesity has led to more cases of type 2 diabetes in younger people.

There's no cure for type 2 diabetes. Losing weight, eating well and exercising can help manage the disease. If diet and exercise aren't enough to control blood sugar, diabetes medications or insulin therapy may be recommended.

Symptoms

Symptoms of type 2 diabetes often develop slowly. In fact, you can be living with type 2 diabetes for years and not know it. When symptoms are present, they may include:

When to see a doctor

See your health care provider if you notice any symptoms of type 2 diabetes.

Causes

Type 2 diabetes is mainly the result of two problems:

Exactly why this happens is not known. Being overweight and inactive are key contributing factors.

How insulin works

Insulin is a hormone that comes from the pancreas — a gland located behind and below the stomach. Insulin controls how the body uses sugar in the following ways:

The role of glucose

Glucose — a sugar — is a main source of energy for the cells that make up muscles and other tissues. The use and regulation of glucose includes the following:

In type 2 diabetes, this process doesn't work well. Instead of moving into the cells, sugar builds up in the blood. As blood sugar levels rise, the pancreas releases more insulin. Eventually the cells in the pancreas that make insulin become damaged and can't make enough insulin to meet the body's needs.

Risk factors

Factors that may increase the risk of type 2 diabetes include:

Complications

Type 2 diabetes affects many major organs, including the heart, blood vessels, nerves, eyes and kidneys. Also, factors that increase the risk of diabetes are risk factors for other serious diseases. Managing diabetes and controlling blood sugar can lower the risk for these complications and other medical conditions, including:

Prevention

Healthy lifestyle choices can help prevent type 2 diabetes. If you've received a diagnosis of prediabetes, lifestyle changes may slow or stop the progression to diabetes.

A healthy lifestyle includes:

For people with prediabetes, metformin (Fortamet, Glumetza, others), a diabetes medication, may be prescribed to reduce the risk of type 2 diabetes. This is usually prescribed for older adults who are obese and unable to lower blood sugar levels with lifestyle changes.

Diagnosis

Type 2 diabetes is usually diagnosed using the glycated hemoglobin (A1C) test. This blood test indicates your average blood sugar level for the past two to three months. Results are interpreted as follows:

If the A1C test isn't available, or if you have certain conditions that interfere with an A1C test, your health care provider may use the following tests to diagnose diabetes:

Random blood sugar test. Blood sugar values are expressed in milligrams of sugar per deciliter (mg/dL) or millimoles of sugar per liter (mmol/L) of blood. Regardless of when you last ate, a level of 200 mg/dL (11.1 mmol/L) or higher suggests diabetes, especially if you also have symptoms of diabetes, such as frequent urination and extreme thirst.

Fasting blood sugar test. A blood sample is taken after you haven't eaten overnight. Results are interpreted as follows:

Oral glucose tolerance test. This test is less commonly used than the others, except during pregnancy. You'll need to not eat for a certain amount of time and then drink a sugary liquid at your health care provider's office. Blood sugar levels then are tested periodically for two hours. Results are interpreted as follows:

Screening. The American Diabetes Association recommends routine screening with diagnostic tests for type 2 diabetes in all adults age 35 or older and in the following groups:

After a diagnosis

If you're diagnosed with diabetes, your health care provider may do other tests to distinguish between type 1 and type 2 diabetes because the two conditions often require different treatments.

Your health care provider will test A1C levels at least two times a year and when there are any changes in treatment. Target A1C goals vary depending on age and other factors. For most people, the American Diabetes Association recommends an A1C level below 7%.

You also receive tests to screen for complications of diabetes and other medical conditions.

Treatment

Management of type 2 diabetes includes:

These steps make it more likely that blood sugar will stay in a healthy range. And they may help to delay or prevent complications.

Healthy eating

There's no specific diabetes diet. However, it's important to center your diet around:

Your health care provider may recommend seeing a registered dietitian, who can help you:

Physical activity

Exercise is important for losing weight or maintaining a healthy weight. It also helps with managing blood sugar. Talk to your health care provider before starting or changing your exercise program to ensure that activities are safe for you.

Weight loss

Weight loss results in better control of blood sugar levels, cholesterol, triglycerides and blood pressure. If you're overweight, you may begin to see improvements in these factors after losing as little as 5% of your body weight. However, the more weight you lose, the greater the benefit to your health. In some cases, losing up to 15% of body weight may be recommended.

Your health care provider or dietitian can help you set appropriate weight-loss goals and encourage lifestyle changes to help you achieve them.

Monitoring your blood sugar

Your health care provider will advise you on how often to check your blood sugar level to make sure you remain within your target range. You may, for example, need to check it once a day and before or after exercise. If you take insulin, you may need to check your blood sugar multiple times a day.

Monitoring is usually done with a small, at-home device called a blood glucose meter, which measures the amount of sugar in a drop of blood. Keep a record of your measurements to share with your health care team.

Continuous glucose monitoring is an electronic system that records glucose levels every few minutes from a sensor placed under the skin. Information can be transmitted to a mobile device such as a phone, and the system can send alerts when levels are too high or too low.

Diabetes medications

If you can't maintain your target blood sugar level with diet and exercise, your health care provider may prescribe diabetes medications that help lower glucose levels, or your provider may suggest insulin therapy. Medicines for type 2 diabetes include the following.

Metformin (Fortamet, Glumetza, others) is generally the first medicine prescribed for type 2 diabetes. It works mainly by lowering glucose production in the liver and improving the body's sensitivity to insulin so it uses insulin more effectively.

Some people experience B-12 deficiency and may need to take supplements. Other possible side effects, which may improve over time, include:

Sulfonylureas help the body secrete more insulin. Examples include glyburide (DiaBeta, Glynase), glipizide (Glucotrol XL) and glimepiride (Amaryl). Possible side effects include:

Glinides stimulate the pancreas to secrete more insulin. They're faster acting than sulfonylureas. But their effect in the body is shorter. Examples include repaglinide and nateglinide. Possible side effects include:

Thiazolidinediones make the body's tissues more sensitive to insulin. An example of this medicine is pioglitazone (Actos). Possible side effects include:

DPP-4 inhibitors help reduce blood sugar levels but tend to have a very modest effect. Examples include sitagliptin (Januvia), saxagliptin (Onglyza) and linagliptin (Tradjenta). Possible side effects include:

GLP-1 receptor agonists are injectable medications that slow digestion and help lower blood sugar levels. Their use is often associated with weight loss, and some may reduce the risk of heart attack and stroke. Examples include exenatide (Byetta, Bydureon Bcise), liraglutide (Saxenda, Victoza) and semaglutide (Rybelsus, Ozempic, Wegovy). Possible side effects include:

SGLT2 inhibitors affect the blood-filtering functions in the kidneys by blocking the return of glucose to the bloodstream. As a result, glucose is removed in the urine. These medicines may reduce the risk of heart attack and stroke in people with a high risk of those conditions. Examples include canagliflozin (Invokana), dapagliflozin (Farxiga) and empagliflozin (Jardiance). Possible side effects include:

Other medicines your health care provider might prescribe in addition to diabetes medications include blood pressure and cholesterol-lowering medicines, as well as low-dose aspirin, to help prevent heart and blood vessel disease.

Insulin therapy

Some people who have type 2 diabetes need insulin therapy. In the past, insulin therapy was used as a last resort, but today it may be prescribed sooner if blood sugar targets aren't met with lifestyle changes and other medicines.

Different types of insulin vary on how quickly they begin to work and how long they have an effect. Long-acting insulin, for example, is designed to work overnight or throughout the day to keep blood sugar levels stable. Short-acting insulin generally is used at mealtime.

Your health care provider will determine what type of insulin is right for you and when you should take it. Your insulin type, dosage and schedule may change depending on how stable your blood sugar levels are. Most types of insulin are taken by injection.

Side effects of insulin include the risk of low blood sugar — a condition called hypoglycemia — diabetic ketoacidosis and high triglycerides.

Weight-loss surgery

Weight-loss surgery changes the shape and function of the digestive system. This surgery may help you lose weight and manage type 2 diabetes and other conditions related to obesity. There are several surgical procedures. All of them help people lose weight by limiting how much food they can eat. Some procedures also limit the amount of nutrients the body can absorb.

Weight-loss surgery is only one part of an overall treatment plan. Treatment also includes diet and nutritional supplement guidelines, exercise and mental health care.

Generally, weight-loss surgery may be an option for adults living with type 2 diabetes who have a body mass index (BMI) of 35 or higher. BMI is a formula that uses weight and height to estimate body fat. Depending on the severity of diabetes or the presence of other medical conditions, surgery may be an option for someone with a BMI lower than 35.

Weight-loss surgery requires a lifelong commitment to lifestyle changes. Long-term side effects may include nutritional deficiencies and osteoporosis.

Pregnancy

People living with type 2 diabetes often need to change their treatment plan during pregnancy and follow a diet that controls carbohydrates. Many people need insulin therapy during pregnancy. They also may need to stop other treatments, such as blood pressure medicines.

There is an increased risk during pregnancy of developing a condition that affects the eyes called diabetic retinopathy. In some cases, this condition may get worse during pregnancy. If you are pregnant, visit an ophthalmologist during each trimester of your pregnancy and one year after you give birth. Or as often as your health care provider suggests.

Signs of trouble

Regularly monitoring your blood sugar levels is important to avoid severe complications. Also, be aware of symptoms that may suggest irregular blood sugar levels and the need for immediate care:

High blood sugar. This condition also is called hyperglycemia. Eating certain foods or too much food, being sick, or not taking medications at the right time can cause high blood sugar. Symptoms include:

Hyperglycemic hyperosmolar nonketotic syndrome (HHNS). This life-threatening condition includes a blood sugar reading higher than 600 mg/dL (33.3 mmol/L). HHNS may be more likely if you have an infection, are not taking medicines as prescribed, or take certain steroids or drugs that cause frequent urination. Symptoms include:

Diabetic ketoacidosis. Diabetic ketoacidosis occurs when a lack of insulin results in the body breaking down fat for fuel rather than sugar. This results in a buildup of acids called ketones in the bloodstream. Triggers of diabetic ketoacidosis include certain illnesses, pregnancy, trauma and medicines — including the diabetes medicines called SGLT2 inhibitors.

The toxicity of the acids made by diabetic ketoacidosis can be life-threatening. In addition to the symptoms of hyperglycemia, such as frequent urination and increased thirst, ketoacidosis may cause:

Low blood sugar. If your blood sugar level drops below your target range, it's known as low blood sugar. This condition also is called hypoglycemia. Your blood sugar level can drop for many reasons, including skipping a meal, unintentionally taking more medication than usual or being more physically active than usual. Symptoms include:

If you have symptoms of low blood sugar, drink or eat something that will quickly raise your blood sugar level. Examples include fruit juice, glucose tablets, hard candy or another source of sugar. Retest your blood in 15 minutes. If levels are not at your target, eat or drink another source of sugar. Eat a meal after your blood sugar level returns to normal.

If you lose consciousness, you need to be given an emergency injection of glucagon, a hormone that stimulates the release of sugar into the blood.

Lifestyle and home remedies

Careful management of type 2 diabetes can reduce the risk of serious — even life-threatening — complications. Consider these tips:

Alternative medicine

Many alternative medicine treatments claim to help people living with diabetes. According to the National Center for Complementary and Integrative Health, studies haven't provided enough evidence to recommend any alternative therapies for blood sugar management. Research has shown the following results about popular supplements for type 2 diabetes:

Talk to your health care provider before starting a dietary supplement or natural remedy. Do not replace your prescribed diabetes medicines with alternative medicines.

Coping and support

Type 2 diabetes is a serious disease, and following your diabetes treatment plan takes commitment. To effectively manage diabetes, you may need a good support network.

Anxiety and depression are common in people living with diabetes. Talking to a counselor or therapist may help you cope with the lifestyle changes and stress that come with a type 2 diabetes diagnosis.

Support groups can be good sources of diabetes education, emotional support and helpful information, such as how to find local resources or where to find carbohydrate counts for a favorite restaurant. If you're interested, your health care provider may be able to recommend a group in your area.

You can visit the American Diabetes Association website to check out local activities and support groups for people living with type 2 diabetes. The American Diabetes Association also offers online information and online forums where you can chat with others who are living with diabetes. You also can call the organization at 800-DIABETES (800-342-2383).

Preparing for an appointment

At your annual wellness visit, your health care provider can screen for diabetes and monitor and treat conditions that increase your risk of diabetes, such as high blood pressure, high cholesterol or a high BMI.

If you are seeing your health care provider because of symptoms that may be related to diabetes, you can prepare for your appointment by being ready to answer the following questions:

If you are diagnosed with diabetes, your health care provider may begin a treatment plan. Or you may be referred to a doctor who specializes in hormonal disorders, called an endocrinologist. Your care team also may include the following specialists:

Talk to your health care provider about referrals to other specialists who may be providing care.

Questions for ongoing appointments

Before any appointment with a member of your treatment team, make sure you know whether there are any restrictions, such as not eating or drinking before taking a test. Questions that you should regularly talk about with your health care provider or other members of the team include:

What to expect from your doctor

Your health care provider is likely to ask you questions at your appointments. Those questions may include:

© 1998-2024 Mayo Foundation for Medical Education and Research (MFMER). All rights reserved. Terms of use.