Type 2 Diabetes: A Complete Overview
Type 2 diabetes is the most common form of diabetes. It develops when the body does not use insulin well and, over time, cannot make enough insulin to keep blood glucose in a healthy range. It often develops slowly and quietly, but it can be managed, and in many cases it can be prevented or delayed. This guide covers causes, risk factors, diagnosis, treatment options, and how to lower the risk of complications.
How common is type 2 diabetes?
The CDC reports that more than 40 million Americans have diabetes and that type 2 diabetes accounts for about 90% to 95% of diagnosed cases. More than 1 in 4 adults with diabetes do not know they have it.
What happens in the body
Normally, insulin from the pancreas helps glucose enter cells. In type 2 diabetes, the main problem early on is insulin resistance: muscle, fat, and liver cells do not respond well to insulin. The pancreas makes extra insulin to compensate. Over time, the insulin-producing beta cells may not keep up, and blood glucose rises. The liver may also release too much glucose. According to NIDDK, type 2 diabetes is most often caused by a combination of factors, including overweight and obesity, physical inactivity, insulin resistance, and genes.
Risk factors
The CDC lists these risk factors for type 2 diabetes and prediabetes:
- Having overweight
- Being 45 years or older
- Having a parent, brother, or sister with type 2 diabetes
- Being physically active less than 3 times a week
- Ever having gestational diabetes or giving birth to a baby weighing more than 9 pounds
- Having polycystic ovary syndrome
The CDC also notes that African American, Hispanic/Latino American, American Indian, Alaska Native, Pacific Islander, and some Asian American people are at higher risk. Type 2 diabetes is usually diagnosed in adults, but it is increasingly seen in children, teens, and young adults.
Symptoms
Many people with type 2 diabetes have no symptoms for years. When symptoms appear, they may include thirst, frequent urination, increased hunger, fatigue, blurry vision, slow-healing sores, frequent infections, numbness or tingling in the hands or feet, and darkened skin in body folds. See our early signs and symptoms guide.
Diagnosis
Type 2 diabetes is diagnosed with blood tests. For non-pregnant adults, the American Diabetes Association uses these thresholds for diabetes:
- A1C of 6.5% or higher
- Fasting plasma glucose of 126 mg/dL or higher
- Two-hour plasma glucose of 200 mg/dL or higher during an oral glucose tolerance test
- Random plasma glucose of 200 mg/dL or higher in someone with classic symptoms of high blood sugar
Results are usually confirmed with a repeat test. A1C results between 5.7% and 6.4% indicate prediabetes. Read more in A1C and blood sugar targets.
Treatment goals
Treatment aims to keep blood glucose, blood pressure, and cholesterol in target ranges to feel well and prevent complications. The ADA's Standards of Care suggest an A1C goal below 7% for many nonpregnant adults, with goals individualized for each person.
Lifestyle: the foundation of care
Healthy eating
There is no single type 2 diabetes diet. Helpful patterns emphasize nonstarchy vegetables, whole foods, lean proteins, healthy fats, and fewer added sugars and refined grains. The plate method is an easy starting point. See diabetes-friendly eating basics and carb counting.
Physical activity
Regular activity improves insulin sensitivity. Federal guidelines recommend at least 150 minutes per week of moderate-intensity activity and muscle-strengthening on two or more days. See exercise and diabetes.
Weight management
For people with overweight, losing weight can improve blood glucose, blood pressure, and cholesterol. Even modest weight loss helps. See weight and diabetes.
Sleep, stress, and tobacco
Good sleep and stress management support blood sugar control. Quitting smoking lowers the risk of heart disease and other complications.
Medicines
Many people with type 2 diabetes also need medicine, and that is not a sign of failure. Type 2 diabetes tends to change over time, and treatment often needs adjusting. Common options include:
- Metformin, often a first medicine for type 2 diabetes.
- GLP-1 receptor agonists and dual GIP/GLP-1 receptor agonists, injectable or oral medicines that lower glucose and support weight loss.
- SGLT2 inhibitors, pills that help the kidneys remove glucose in the urine.
- DPP-4 inhibitors, sulfonylureas, and thiazolidinediones, among others.
- Insulin, which some people with type 2 diabetes need.
Some of these medicines have shown heart or kidney benefits in people with certain conditions, which can guide your provider's choice. Our article on metformin and common diabetes medications covers them in more detail. The ADA also has a guide to oral and injectable medications.
Monitoring
Your provider will check your A1C regularly, often every three to six months. Whether you need to check your blood sugar at home depends on your treatment; it is especially important if you take insulin or medicines that can cause low blood sugar. See checking blood sugar and CGMs.
Preventing complications
NIDDK explains that over time, high blood glucose can damage blood vessels and nerves and lead to heart disease, stroke, kidney disease, eye problems, nerve damage, and foot problems. The CDC notes diabetes is a leading cause of kidney failure, lower-limb amputations, and adult blindness. Regular care makes a big difference:
- Keep A1C, blood pressure, and cholesterol near your targets.
- Get a dilated eye exam as recommended. See eye health and retinopathy.
- Have yearly kidney tests (urine albumin and eGFR). See kidney health.
- Check your feet daily and have them examined at visits. See diabetic foot care.
- Manage heart risk. See heart health.
- Stay up to date on vaccines recommended by your provider.
Can type 2 diabetes go into remission?
Some people, particularly with significant weight loss, are able to bring their blood glucose back below the diabetes range without diabetes medicines. This is sometimes called remission. It is not the same as a cure; blood glucose can rise again, so ongoing monitoring is still needed. Talk with your care team about what is realistic for you.
Preventing type 2 diabetes
If you have prediabetes or risk factors, the CDC states that losing a small amount of weight (around 5% to 7% of body weight) and getting at least 150 minutes per week of activity can lower your risk. The CDC-led National Diabetes Prevention Program can lower the risk of type 2 diabetes by 58% (71% for people over 60). See our prediabetes guide.
Getting support
Diabetes self-management education and support (DSMES) helps people learn skills for eating, activity, medicines, and monitoring. Ask your doctor for a referral. Emotional support matters too; diabetes distress and depression are common and treatable.
Key takeaways
- Type 2 diabetes accounts for about 90% to 95% of diagnosed diabetes and often has no early symptoms.
- It results from insulin resistance and declining insulin production over time.
- Healthy eating, activity, and weight management are the foundation of treatment; many people also need medicine.
- Regular checks of A1C, blood pressure, cholesterol, eyes, kidneys, and feet help prevent complications.
Sources
Links to the sources cited above appear in the text. We rely on the Centers for Disease Control and Prevention (CDC), the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), and the American Diabetes Association (ADA).
Related guides: Diabetes basics
- What Is Diabetes? Type 1 vs. Type 2 Explained
- Type 1 Diabetes: Causes, Diagnosis, and Treatment
- Gestational Diabetes: What to Know During and After Pregnancy
- Prediabetes: What It Is and How to Reverse Course
- Early Signs and Symptoms of Diabetes
- Diabetes Symptoms in Women: Signs to Know
- Diabetes in Children and Teens: A Guide for Families
- Diabetes Myths vs. Facts
- LADA (Type 1.5 Diabetes): Autoimmune Diabetes in Adults
- MODY and Rare Types of Diabetes
- Insulin Resistance: Causes, Signs, and How to Improve It