Type 2 Diabetes: Overview and More

Type 2 diabetes is a chronic disease in which the body is unable to adequately control the levels of glucose (sugar) in the blood, which can lead to dangerously high blood glucose (hyperglycemia). The symptoms of type 2 diabetes include increased thirst, frequent urination, extreme fatigue, and slow healing of wounds. As the disease progresses, complications such as skin disorders, sexual dysfunction, kidney disease, nerve damage, and vision loss can develop.

Type 2 diabetes develops when the pancreas begins to produce less insulin (a hormone that controls blood sugar levels) or when the body becomes less sensitive to the effects of insulin—known as insulin resistance. A simple blood test can diagnose type 2 diabetes.

Once verified, treatment depends on a person’s age, weight, blood sugar level, and how advanced the disease is. For some this might mean relying solely on lifestyle modifications such as weight loss, dietary changes, and exercise. For others, managing type 2 diabetes may require supplemental insulin and/or diabetes medications as well.

Lack of insulin or insulin resistance causes higher than normal levels of glucose in type 2 diabetes.

Type 2 Diabetes Symptoms

In the earliest stages of type 2 diabetes, most people do not experience obvious symptoms. It isn’t until blood sugar levels become very high that symptoms begin to appear. Left untreated, type 2 diabetes can lead to serious and even debilitating or life-threatening complications.


The most common symptoms of type 2 diabetes include:

  • Polyuria: An increase in urination that occurs when the kidneys draw water from tissue in order to dilute excess glucose in the blood and flush it out of the body. The kidneys aren’t able to reabsorb this fluid, which results in more frequent urination.
  • Polydipsia: Excessive thirst. As the body pulls water from tissues, the body becomes dehydrated, prompting what some people describe as unquenchable thirst.
  • Extreme fatigue: Because too little insulin is being produced by the pancreas or the body isn’t able to use it properly, cells in the body are deprived of the glucose that is the main source of energy. The result: tiredness and extreme fatigue.
  • Polyphasia: This is excessive hunger that occurs when cells aren’t able to access glucose, which trigger hormones that send hunger signals to the brain.
  • Neuropathy: Numbness, tingling, or a feeling of “pins and needles” that occurs over time as excess sugar damages the nerves.
  • Slow healing of wounds: Excess sugar in the blood affects circulation, making it harder for blood to reach injured areas in order for healing to take place.
  • Vision changes: When fluid is pulled from the lenses of the eyes to help dilute glucose in the blood, the ability to focus is impaired and vision can become blurry. Damage to the eye may occur even before a diagnosis of diabetes exists.

Less common symptoms of type 2 diabetes include:

  • Dry mouth
  • Dry skin
  • Skin tags
  • Acanthosis nigricans (dark velvety patches in the armpits groin, skin folds, and joints of the fingers and toes)
  • Frequent infections
  • Unexplained weight loss


When not managed well, type 2 diabetes can lead to a number of serious, debilitating, and even potentially fatal complications, most of which result from damage to small blood vessels (microvascular damage) or damage to large blood vessels (macrovascular damage).

  • Nephropathy (kidney disease)
  • Neuropathy (nerve damage that most often affects hands and feet but also can lead to erectile dysfunction)
  • Retinopathy (damage to the retina of the eye that can lead to vision loss)
  • Peripheral arterial disease (a disease that affects the vessels in the lower and upper extremities)
  • Hypertension (high blood pressure )
  • Heart disease
  • Gastroparesis (nerve damage that affects the stomach)
  • Depression


Type 2 diabetes is the result of one of two situations: Either the pancreas begins releasing too little insulin, a hormone released within a few minutes of eating to help the body store glucose, or the body isn’t able to respond adequately to insulin (insulin resistance).

There are a number of risk factors for type 2 diabetes:

  • Obesity: This is one of the major causes of diabetes. Excess body fat can cause insulin resistance.
  • Sedentary lifestyle: Physical activity helps the body use insulin, and so too little movement throughout the day can increase the risk of type 2 diabetes.
  • Genes: Family history is a more significant indicator of type 1 diabetes risk. It has been shown that in twins, however, that when one sibling has type 2 diabetes, the other’s risk is three in four.
  • Age: The risk of type 2 diabetes increases with age.
  • Ethnicity: Type 2 diabetes tends to be more common in people who are African American, Mexican American, Native American, Native Hawaiian, Pacific Islander, and Asian American—particularly those who are overweight and sedentary.
  • Tobacco use: Smoking can increase blood sugar and lead to insulin resistance. According to the Centers for Disease Control and Prevention, smokers are 30% to 40% more likely to develop type 2 diabetes than nonsmokers.


Diabetes is diagnosed with one or more of the following blood tests, which may be repeated if the results are inconclusive.

  • Fasting blood sugar test: A measurement of blood sugar following eight hours of not eating
  • Glucose tolerance test: A test of the body’s response to sugar performed by having a person drink a beverage containing 75 grams of sugar over the course of two hours, after which his or her blood sugar is measured
  • Hemoglobin A1C: Looks at glucose levels over the course of three months
  • Random blood sugar test: Blood test done on someone who’s experiencing symptoms of diabetes, such as increased thirst, fatigue, increased urination


Anyone who’s diagnosed with type 2 diabetes will be counseled to make certain lifestyle modifications. Depending on how advanced the disease is and other individual factors, treatment may also include supplemental insulin and/or medication.

Lifestyle Modifications

Simple changes can go a long way toward keeping type 2 diabetes under control, and perhaps even reversing its course.

  • Weight loss: Losing just 5 percent to 10 percent percent of body weight can greatly improve blood sugar control, according to Johns Hopkins Medicine. (In fact, shedding pounds can have such a profound effect blood glucose that for people diagnosed with prediabetes, this amount of weight loss can lower the risk of progressing to type 2 diabetes by 58 percent.)
  • Dietary changes: A balanced diet that’s low in carbohydrates and rich in non-starchy vegetables, lean protein, and healthy fats can support weight loss as well as blood glucose control.
  • Exercise: Physical activity can play a key role in managing blood sugars and preventing complications of diabetes. Regular exercise also can help with weight loss. According to the ADA, adults with diabetes should get at least 150 minutes of moderate-intensity aerobic physical activity per week (spread over at least three days with no more than two consecutive days without exercise).
  • Smoking cessation: Kicking the habit will help to control blood glucose.


There are many classes of drugs available to people with type 2 diabetes who need help managing their blood glucose beyond lifestyle modifications and insulin.

Drug Class Mechanism Specific Medications
DPP-4 inhibitors Blocks an enzyme that destroys a hormone called incretin that helps the body produce more insulin when necessary and reduce the amount of glucose produced by the liver when it is not needed Januvia (sitagliptin)

Galvus (vildagliptin)

Onglyza (saxagliptin)

Tradjenta (linagliptin)

Nesina (alogliptin)

Incretin mimetics Mimics the action of incretins to stimulate production of 
 slows the rate of digestion so that glucose enters the blood more slowly.
Byetta (exenatide)

Victoza (liraglutide)

Trulicity (dulaglutide)

Lyxumia (lixisenatide)

Selective sodium-glucose transporter-2 (SSGT-2) inhibitors Lowers blood sugar by causing the kidneys to remove glucose from the body through urine Invokana (canagliflozin)

Farxiga (dapagliflozin)

Jardiance (empagliflozin)

Amylin analogs Lowers blood sugar levels as a manmade version of the hormone amylin  Symlin (pramlintide acetate)
Sulfonylureas Stimulates the pancreas to release more insulin into the bloodstream Orinase (tolbutamide)

Tolinase (tolazamide)

Diabinese (chlorpropamide)

Glucotrol (glipizide)

Micronase (glyburide)

Diabeta (glyburide)

Amaryl (glimepiride)

Biguanides Lowers the amount of glucose produced by the liver while making the body more sensitive to insulin Glucophage (metformin)

Glucophage XR (extended-release metformin)

Alpha-glucosidase inhibitors Delays the conversion of carbohydrates to glucose during digestion Precose (acarbose)

Glyset (miglitol)

Thiazolidinediones Sensitizes muscle and fat cells to accept insulin more readily Avandia (rosiglitazone)

Actos (pioglitazone)

Meglitinides Stimulates insulin production if there is glucose in the blood Prandin (repaglinide)

Starlix (nateglinide)


If lifestyle modifications and medication aren’t enough to control blood sugar levels, supplemental insulin may be needed. Insulin usually is self-administered with a needle and a syringe several times a day. Some people with type 2 diabetes who are taking oral medications may only need a single shot of insulin each day. Others may need insulin injections two, three, or four times a day to reach their blood glucose targets. Insulin also can be administered via an insulin pump or patch that’s worn on the body.

Blood Sugar Testing

Frequent blood glucose testing is a cornerstone of effective diabetes management by providing a picture of how effective diet, exercise, insulin, and/or medications are in regulating glucose levels. Test results also can provide valuable information to a doctor to help make adjustments to your overall care plan. Blood glucose testing uses a small device that can measure glucose levels by analyzing a drop of blood taken from a finger.

A Word From Verywell

Diabetes is a chronic condition that must be managed daily, but it is manageable. You can live a long, healthy life with diabetes by sticking to the treatment plan your doctor prescribes. You also can get support from many places. The American Diabetes Association advises that all persons with diabetes receive diabetes self-management education (DSME) when they’re diagnosed. And a certified diabetes educator or another qualified health professional can give you the tools you need to understand and take care of your diabetes.

Most important, go easy on yourself: Sometimes you can be doing everything perfectly and your blood sugars start to creep up. Because diabetes is a progressive disease, your body slowly stops making insulin over time. If you’ve had diabetes for a very long time, try not to be discouraged if your doctor has to increase your medication or discusses insulin with you. Continue to do what you can to improve your health. Keep an open dialogue as you continue to manage your condition.

Type 2 Diabetes Doctor Discussion Guide

Get our printable guide for your next doctor’s appointment to help you ask the right questions.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Institute of Diabetes and Digestive and Kidney Diseases. Symptoms & causes of diabetes. December 2016.

  2. American Diabetes Association. Complications.

  3. American Diabetes Association. Learn the genetics of diabetes.

  4. Centers for Disease Control and Prevention. Smoking and diabetes.

  5. National Institute of Diabetes and Digestive and Kidney Diseases. Diabetes tests & diagnosis.

  6. John Hopkins Medicine. Diabetes. Digestive Weight Loss Center.

  7. Colberg SR, Sigal RJ, Fernhall B, et al. Exercise and type 2 diabetes: the American College of Sports Medicine and the American Diabetes Association: joint position statement. Diabetes Care. 2010;33(12):e147-67. doi:10.2337/dc10-9990

  8. National Institute of Diabetes and Digestive and Kidney Diseases. Insulin, medicines, & other diabetes treatments. December 2016.

  9. American Diabetes Association. 7. Diabetes Technology: Standards of Medical Care in Diabetes-2020Diabetes Care. 2020;43(Suppl 1):S77-S88. doi:10.2337/dc20-S007

  10. Powers MA, Bardsley J, Cypress M, et al. Diabetes self-management education and support in type 2 diabetes: a joint position statement of the American Diabetes Association, the American Association of Diabetes Educators, and the Academy of Nutrition and Dietetics. Clin Diabetes. 2016;34(2):70-80. doi:10.2337/diaclin.34.2.70

Additional Reading

  • American Diabetes Association, American Association of Diabetes Educators, and the American Academy of Nutrition and Dietetics. Diabetes self-management education and support in type 2 diabetes 2015.

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