Type 2 diabetes is an impairment in the way the body regulates and uses sugar (glucose) as a fuel. This long-term (chronic) condition results in too much sugar circulating in the bloodstream. Eventually, high blood sugar levels can lead to disorders of the circulatory, nervous and immune systems.
In type 2 diabetes, there are primarily two interrelated problems at work. Your pancreas does not produce enough insulin — a hormone that regulates the movement of sugar into your 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, but losing weight, eating well and exercising can help you manage the disease. If diet and exercise aren't enough to manage your blood sugar, you may also need diabetes medications or insulin therapy.
Signs and 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 signs and symptoms are present, they may include:
· Increased thirst
· Frequent urination
· Increased hunger
· Unintended weight loss
· Blurred vision
· Slow-healing sores
· Frequent infections
· Numbness or tingling in the hands or feet
· Areas of darkened skin, usually in the armpits and neck
When to see a doctor
See your doctor if you notice any signs or symptoms of type 2 diabetes.
Type 2 diabetes is primarily the result of two interrelated problems:
· Cells in muscle, fat and the liver become resistant to insulin. Because these cells don't interact in a normal way with insulin, they don't take in enough sugar.
· The pancreas is unable to produce enough insulin to manage blood sugar levels.
Exactly why this happens is unknown, but being overweight and inactive are key contributing factors.
How insulin works
Insulin is a hormone that comes from the gland situated behind and below the stomach (pancreas). Insulin regulates how the body uses sugar in the following ways:
· Sugar in the bloodstream triggers the pancreas to secrete insulin.
· Insulin circulates in the bloodstream, enabling sugar to enter your cells.
· The amount of sugar in your bloodstream drops.
· In response to this drop, the pancreas releases less insulin.
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:
· Glucose comes from two major sources: food and your liver.
· Glucose is absorbed into the bloodstream, where it enters cells with the help of insulin.
· Your liver stores and makes glucose.
· When your glucose levels are low, such as when you haven't eaten in a while, the liver breaks down stored glycogen into glucose to keep your glucose level within a normal range.
In type 2 diabetes, this process doesn't work well. Instead of moving into your cells, sugar builds up in your bloodstream. As blood sugar levels increase, the insulin-producing beta cells in the pancreas release more insulin. Eventually these cells become impaired and can't make enough insulin to meet the body's demands.
In the less common type 1 diabetes, the immune system mistakenly destroys the beta cells, leaving the body with little to no insulin.
Factors that may increase your risk of type 2 diabetes include:
· Weight. Being overweight or obese is a main risk.
· Fat distribution. Storing fat mainly in your abdomen — rather than your hips and thighs — indicates a greater risk. Your risk of type 2 diabetes rises if you're a man with a waist circumference above 40 inches (101.6 centimeters) or a woman with a measurement above 35 inches (88.9 centimeters).
· Inactivity. The less active you are, the greater your risk. Physical activity helps control your weight, uses up glucose as energy and makes your cells more sensitive to insulin.
· Family history. The risk of type 2 diabetes increases if your parent or sibling has type 2 diabetes.
· Race and ethnicity. Although it's unclear why, people of certain races and ethnicities — including Black, Hispanic, Native American and Asian people, and Pacific Islanders — are more likely to develop type 2 diabetes than white people are.
· Blood lipid levels. An increased risk is associated with low levels of high-density lipoprotein (HDL) cholesterol — the "good" cholesterol — and high levels of triglycerides.
· Age. The risk of type 2 diabetes increases as you get older, especially after age 45.
· Prediabetes. Prediabetes is a condition in which your blood sugar level is higher than normal, but not high enough to be classified as diabetes. Left untreated, prediabetes often progresses to type 2 diabetes.
· Pregnancy-related risks. Your risk of developing type 2 diabetes increases if you developed gestational diabetes when you were pregnant or if you gave birth to a baby weighing more than 9 pounds (4 kilograms).
· Polycystic ovary syndrome. Having polycystic ovary syndrome — a common condition characterized by irregular menstrual periods, excess hair growth and obesity — increases the risk of diabetes
· Areas of darkened skin, usually in the armpits and neck. This condition often indicates insulin resistance.
Type 2 diabetes affects many major organs, including your heart, blood vessels, nerves, eyes and kidneys. Also, factors that increase the risk of diabetes are risk factors for other serious chronic diseases. Managing diabetes and controlling your blood sugar can lower your risk for these complications or coexisting conditions (comorbidities).
Potential complications of diabetes and frequent comorbidities include:
· Heart and blood vessel disease. Diabetes is associated with an increased risk of heart disease, stroke, high blood pressure and narrowing of blood vessels (atherosclerosis).
· Nerve damage (neuropathy) in limbs. High blood sugar over time can damage or destroy nerves, resulting in tingling, numbness, burning, pain or eventual loss of feeling that usually begins at the tips of the toes or fingers and gradually spreads upward.
· Other nerve damage. Damage to nerves of the heart can contribute to irregular heart rhythms. Nerve damage in the digestive system can cause problems with nausea, vomiting, diarrhea or constipation. For men, nerve damage may cause erectile dysfunction.
· Kidney disease. Diabetes may lead to chronic kidney disease or irreversible end-stage kidney disease, which may require dialysis or a kidney transplant.
· Eye damage. Diabetes increases the risk of serious eye diseases, such as cataracts and glaucoma, and may damage the blood vessels of the retina, potentially leading to blindness.
· Skin conditions. Diabetes may leave you more susceptible to skin problems, including bacterial and fungal infections.
· Slow healing. Left untreated, cuts and blisters can become serious infections, which may heal poorly. Severe damage might require toe, foot or leg amputation.
· Hearing impairment. Hearing problems are more common in people with diabetes.
· Sleep apnea. Obstructive sleep apnea is common in people living with type 2 diabetes. Obesity may be the main contributing factor to both conditions. It's not clear whether treating sleep apnea improves blood sugar control.
· Dementia. Type 2 diabetes seems to increase the risk of Alzheimer's disease and other disorders that cause dementia. Poor control of blood sugar levels is linked to more-rapid decline in memory and other thinking skills.
Healthy lifestyle choices can help prevent type 2 diabetes, and that's true even if you have biological relatives living with diabetes. If you've received a diagnosis of prediabetes, lifestyle changes may slow or stop the progression to diabetes.
A healthy lifestyle includes:
· Eating healthy foods. Choose foods lower in fat and calories and higher in fiber. Focus on fruits, vegetables and whole grains.
· Getting active. Aim for 150 or more minutes a week of moderate to vigorous aerobic activity, such as a brisk walk, bicycling, running or swimming.
· Losing weight. Losing a modest amount of weight and keeping it off can delay the progression from prediabetes to type 2 diabetes. If you have prediabetes, losing 7% to 10% of your body weight can reduce the risk of diabetes.
· Avoiding inactivity for long periods. Sitting still for long periods can increase your risk of type 2 diabetes. Try to get up every 30 minutes and move around for at least a few minutes.
For people with prediabetes, metformin (Fortamet, Glumetza, others), an oral 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.
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:
· Below 5.7% is normal.
· 5.7% to 6.4% is diagnosed as prediabetes.
· 6.5% or higher on two separate tests indicates diabetes.
If the A1C test isn't available, or if you have certain conditions that interfere with an A1C test, your doctor 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 signs and symptoms of diabetes, such as frequent urination and extreme thirst.
Fasting blood sugar test. A blood sample is taken after an overnight fast. Results are interpreted as follows:
· Less than 100 mg/dL (5.6 mmol/L) is normal.
· 100 to 125 mg/dL (5.6 to 6.9 mmol/L) is diagnosed as prediabetes.
· 126 mg/dL (7 mmol/L) or higher on two separate tests is diagnosed as diabetes.
Oral glucose tolerance test. This test is less commonly used than the others, except during pregnancy. You'll need to fast overnight and then drink a sugary liquid at the doctor's office. Blood sugar levels are tested periodically for the next two hours. Results are interpreted as follows:
· Less than 140 mg/dL (7.8 mmol/L) is normal.
· 140 to 199 mg/dL (7.8 mmol/L and 11.0 mmol/L) is diagnosed as prediabetes.
· 200 mg/dL (11.1 mmol/L) or higher after two hours suggests diabetes.
Screening. The American Diabetes Association recommends routine screening with diagnostic tests for type 2 diabetes in all adults age 45 or older and in the following groups:
· People younger than 45 who are overweight or obese and have one or more risk factors associated with diabetes
· Women who have had gestational diabetes
· People who have been diagnosed with prediabetes
· Children who are overweight or obese and who have a family history of type 2 diabetes or other risk factors
After a diagnosis
If you're diagnosed with diabetes, your doctor or health care provider may do other tests to distinguish between type 1 and type 2 diabetes — since the two conditions often require different treatments.
Your health care provider will repeat the test A1C levels at least two times a year and when there are any changes in treatment. Target A1C goals vary depending on your age and other factors. For most people, the American Diabetes Association recommends an A1C level below 7%.
You will also receive regular diagnostic tests to screen for complications of diabetes or comorbid conditions.
Management of type 2 diabetes includes:
· Healthy eating
· Regular exercise
· Weight loss
· Possibly, diabetes medication or insulin therapy
· Blood sugar monitoring
These steps will help keep your blood sugar level closer to normal, which can delay or prevent complications.
Contrary to popular perception, there's no specific diabetes diet. However, it's important to center your diet around:
· A regular schedule for meals and healthy snacks
· Smaller portion sizes
· More high-fiber foods, such as fruits, nonstarchy vegetables and whole grains
· Fewer refined grains, starchy vegetables and sweets
· Modest servings of low-fat dairy, low-fat meats and fish
· Healthy cooking oils, such as olive oil or canola oil
· Fewer calories
Your health care provider may recommend seeing a registered dietitian, who can help you:
· Identify healthy choices among your food preferences
· Plan well-balanced, nutritional meals
· Develop new habits and address barriers to changing habits
· Monitor carbohydrate intake to keep your blood sugar levels more stable
Exercise is important for losing weight or maintaining a healthy weight. It also helps with regulating blood sugar levels. Talk to your primary health care provider before starting or changing your exercise program to ensure that activities are safe for you.
Aerobic exercise. Choose an aerobic exercise that you enjoy, such as walking, swimming, biking or running. Adults should aim for 30 minutes or more of moderate aerobic exercise on most days of the week, or at least 150 minutes a week. Children should have 60 minutes of moderate to vigorous aerobic exercise daily.
Resistance exercise. Resistance exercise increases your strength, balance and ability to perform activities of daily living more easily. Resistance training includes weightlifting, yoga and calisthenics.
Adults living with type 2 diabetes should aim for two to three sessions of resistance exercise each week. Children should engage in activities that build strength and flexibility at least three days a week. This can include resistance exercises, sports and climbing on playground equipment.
Limit inactivity. Breaking up long bouts of inactivity, such as sitting at the computer, can help control blood sugar levels. Take a few minutes to stand, walk around or do some light activity every 30 minutes.
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 and disease management.
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 do this 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 your blood. You should 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 your skin. Information can be transmitted to a mobile device such as your phone, and the system can send alerts when levels are too high or too low.
If you can't maintain your target blood sugar level with diet and exercise, your doctor may prescribe diabetes medications that help lower insulin levels or insulin therapy. Drug treatments for type 2 diabetes include the following.
Metformin (Fortamet, Glumetza, others) is generally the first medication prescribed for type 2 diabetes. It works primarily by lowering glucose production in the liver and improving your body's sensitivity to insulin so that your body 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:
· Abdominal pain
Sulfonylureas help your body secrete more insulin. Examples include glyburide (DiaBeta, Glynase), glipizide (Glucotrol) and glimepiride (Amaryl). Possible side effects include:
· Low blood sugar
· Weight gain
Glinides stimulate the pancreas to secrete more insulin. They're faster acting than sulfonylureas, and the duration of their effect in the body is shorter. Examples include repaglinide and nateglinide. Possible side effects include:
· Low blood sugar
· Weight gain
Thiazolidinediones make the body's tissues more sensitive to insulin. Examples include rosiglitazone (Avandia) and pioglitazone (Actos). Possible side effects include:
· Risk of congestive heart failure
· Risk of bladder cancer (pioglitazone)
· Risk of bone fractures
· High cholesterol (rosiglitazone)
· Weight gain
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:
· Risk of pancreatitis
· Joint pain
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), liraglutide (Saxenda, Victoza) and semaglutide (Rybelsus, Ozempic). Possible side effects include:
· Risk of pancreatitis
SGLT2 inhibitors affect the blood-filtering functions in your kidneys by inhibiting the return of glucose to the bloodstream. As a result, glucose is excreted in the urine. These drugs 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:
· Risk of amputation (canagliflozin)
· Risk of bone fractures (canagliflozin)
· Risk of gangrene
· Vaginal yeast infections
· Urinary tract infections
· Low blood pressure
· High cholesterol
Other medications your doctor might prescribe in addition to diabetes medications include blood pressure and cholesterol-lowering medications, as well as low-dose aspirin, to help prevent heart and blood vessel disease.
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 medications.
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 might be used at mealtime.
Your doctor will determine what type of insulin is appropriate 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 (hypoglycemia), diabetic ketoacidosis and high triglycerides.
Weight-loss surgery changes the shape and function of your digestive system. This surgery may help you lose weight and manage type 2 diabetes and other conditions related to obesity. There are various surgical procedures, but all of them help you lose weight by limiting how much food you can eat. Some procedures also limit the amount of nutrients you can absorb.
Weight-loss surgery is only one part of an overall treatment plan. Your treatment will also include 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 comorbid 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 include nutritional deficiencies and osteoporosis.
Women with type 2 diabetes will likely need to change their treatment plans and adhere to diets that carefully controls carbohydrate intake. Many women will need insulin therapy during pregnancy and may need to discontinue other treatments, such as blood pressure medications.
There is an increased risk during pregnancy of developing diabetic retinopathy or a worsening of the condition. If you are pregnant or planning a pregnancy, visit an ophthalmologist during each trimester of your pregnancy, one year postpartum or as advised.
Signs of trouble
Regularly monitoring your blood sugar levels is important to avoid severe complications. Also, be aware of signs and symptoms that may suggest irregular blood sugar levels and the need for immediate care:
High blood sugar (hyperglycemia). Eating certain foods or too much food, being sick, or not taking medications at the right time can cause high blood sugar. Signs and symptoms include:
· Frequent urination
· Increased thirst
· Dry mouth
· Blurred vision
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. Signs and symptoms include:
· Dry mouth
· Extreme thirst
· Dark urine
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 medications — including the diabetes medications called SGLT2 inhibitors.
Although diabetic ketoacidosis is usually less severe in type 2 diabetes, the toxicity of the acids can be life-threatening. In addition to the signs and symptoms of hypoglycemia, such as frequent urination and increased thirst, ketoacidosis may result in:
· Abdominal pain
· Shortness of breath
· Fruity-smelling breath
Low blood sugar. If your blood sugar level drops below your target range, it's known as low blood sugar (hypoglycemia). Your blood sugar level can drop for many reasons, including skipping a meal, unintentionally taking more medication than usual or being more physical activity than usual. Signs and symptoms include:
By Mayo Clinic Staff