Type 2 diabetes, formerly known as adult-onset diabetes, is a form of

diabetes mellitus Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level (hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ...

that is characterized by high blood sugar,

insulin resistance Insulin resistance (IR) is a pathological condition in which cells fail to respond normally to the hormone insulin. Insulin is a hormone that facilitates the transport of glucose from blood into cells, thereby reducing blood glucose (blood suga ...

, and relative lack of

insulin Insulin (, from Latin ''insula'', 'island') is a peptide hormone produced by beta cells of the pancreatic islets encoded in humans by the ''INS'' gene. It is considered to be the main anabolic hormone of the body. It regulates the metabol ...

. Common symptoms include increased thirst,

frequent urination Frequent urination, or urinary frequency (sometimes called pollakiuria), is the need to urinate more often than usual. Diuretics are medications that increase urinary frequency. Nocturia is the need of frequent urination at night. The most common ...

, and unexplained

weight loss Weight loss, in the context of medicine, health, or physical fitness, refers to a reduction of the total body mass, by a mean loss of fluid, body fat (adipose tissue), or lean mass (namely bone mineral deposits, muscle, tendon, and other con ...

. Symptoms may also include increased hunger, feeling tired, and

sores Sores is a French surname. Notable people with the surname include: * Jacques de Sores Jacques de Sores was a French pirate and corsair who attacked and burnt Havana, Cuba in 1555. Other than his attack on Havana, little is known of de Sores. ...

that do not heal. Often symptoms come on slowly. Long-term complications from high blood sugar include

heart disease Cardiovascular disease (CVD) is a class of diseases that involve the heart or blood vessels. CVD includes coronary artery diseases (CAD) such as angina and myocardial infarction (commonly known as a heart attack). Other CVDs include stroke, ...

, strokes,

diabetic retinopathy Diabetic retinopathy (also known as diabetic eye disease), is a medical condition in which damage occurs to the retina due to diabetes mellitus. It is a leading cause of blindness in developed countries. Diabetic retinopathy affects up to 80 perc ...

which can result in

blindness Visual impairment, also known as vision impairment, is a medical definition primarily measured based on an individual's better eye visual acuity; in the absence of treatment such as correctable eyewear, assistive devices, and medical treatment� ...

, kidney failure, and poor blood flow in the limbs which may lead to

amputation Amputation is the removal of a limb by trauma, medical illness, or surgery. As a surgical measure, it is used to control pain or a disease process in the affected limb, such as malignancy or gangrene. In some cases, it is carried out on ind ...

s. The sudden onset of hyperosmolar hyperglycemic state may occur; however, ketoacidosis is uncommon. Type 2 diabetes primarily occurs as a result of

obesity Obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it may negatively affect health. People are classified as obese when their body mass index (BMI)—a person's ...

and lack of exercise. Some people are genetically more at risk than others. Type 2 diabetes makes up about 90% of cases of

diabetes Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level (hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ...

, with the other 10% due primarily to type 1 diabetes and

gestational diabetes Gestational diabetes is a condition in which a woman without diabetes develops high blood sugar levels during pregnancy. Gestational diabetes generally results in few symptoms; however, it increases the risk of pre-eclampsia, depression, and o ...

. In type 1 diabetes there is a lower total level of insulin to control blood glucose, due to an

autoimmune In immunology, autoimmunity is the system of immune responses of an organism against its own healthy cells, tissues and other normal body constituents. Any disease resulting from this type of immune response is termed an " autoimmune disease" ...

induced loss of insulin-producing beta cells in the

pancreas The pancreas is an organ of the digestive system and endocrine system of vertebrates. In humans, it is located in the abdomen behind the stomach and functions as a gland. The pancreas is a mixed or heterocrine gland, i.e. it has both an en ...

. Diagnosis of diabetes is by blood tests such as fasting plasma glucose, oral glucose tolerance test, or glycated hemoglobin (A1C). Type 2 diabetes is largely preventable by staying a normal weight, exercising regularly, and eating a healthy diet (high in fruits and vegetables and low in sugar and saturated fats). Treatment involves exercise and dietary changes. If blood sugar levels are not adequately lowered, the medication metformin is typically recommended. Many people may eventually also require insulin injections. In those on insulin, routinely checking blood sugar levels is advised; however, this may not be needed in those taking pills.

Bariatric surgery Bariatric surgery (or weight loss surgery) includes a variety of procedures performed on people who are obese. Long term weight loss through the standard of care procedures ( Roux en-Y bypass, sleeve gastrectomy, and biliopancreatic diversi ...

often improves diabetes in those who are obese. Rates of type 2 diabetes have increased markedly since 1960 in parallel with obesity. As of 2015 there were approximately 392 million people diagnosed with the disease compared to around 30 million in 1985. Typically it begins in middle or older age, although rates of type 2 diabetes are increasing in young people. Type 2 diabetes is associated with a ten-year-shorter life expectancy. Diabetes was one of the first diseases ever described, dating back to an Egyptian manuscript from BCE. The importance of insulin in the disease was determined in the 1920s.

Signs and symptoms

The classic symptoms of diabetes are frequent urination (

polyuria Polyuria () is excessive or an abnormally large production or passage of urine (greater than 2.5 L or 3 L over 24 hours in adults). Increased production and passage of urine may also be termed diuresis. Polyuria often appears in conjunction wi ...

), increased thirst ( polydipsia), increased hunger ( polyphagia), and

. Other symptoms that are commonly present at diagnosis include a history of

blurred vision Blurred vision is an ocular symptom where vision becomes less precise and there is added difficulty to resolve fine details. Temporary blurred vision may involve dry eyes, eye infections, alcohol poisoning, hypoglycemia, or low blood pressu ...

, itchiness, peripheral neuropathy, recurrent vaginal infections, and

fatigue Fatigue describes a state of tiredness that does not resolve with rest or sleep. In general usage, fatigue is synonymous with extreme tiredness or exhaustion that normally follows prolonged physical or mental activity. When it does not resolve ...

. Other symptoms may include

loss of taste Ageusia (from negative prefix ''a-'' and Ancient Greek ''γεῦσις'' geûsis 'taste') is the loss of taste functions of the tongue, particularly the inability to detect sweetness, sourness, bitterness, saltiness, and umami (meaning 'pleasant/ ...

. Many people, however, have no symptoms during the first few years and are diagnosed on routine testing. A small number of people with type 2 diabetes can develop a hyperosmolar hyperglycemic state (a condition of very high blood sugar associated with a decreased level of consciousness and low blood pressure).

Complications

Type 2 diabetes is typically a chronic disease associated with a ten-year-shorter life expectancy. This is partly due to a number of complications with which it is associated, including: two to four times the risk of

cardiovascular disease Cardiovascular disease (CVD) is a class of diseases that involve the heart or blood vessels. CVD includes coronary artery diseases (CAD) such as angina and myocardial infarction (commonly known as a heart attack). Other CVDs include stroke, ...

, including ischemic heart disease and stroke; a 20-fold increase in lower limb amputations, and increased rates of hospitalizations. In the developed world, and increasingly elsewhere, type 2 diabetes is the largest cause of nontraumatic

and kidney failure. It has also been associated with an increased risk of cognitive dysfunction and

dementia Dementia is a disorder which manifests as a set of related symptoms, which usually surfaces when the brain is damaged by injury or disease. The symptoms involve progressive impairments in memory, thinking, and behavior, which negatively affe ...

through disease processes such as Alzheimer's disease and vascular dementia. Other complications include hyperpigmentation of skin (

acanthosis nigricans Acanthosis nigricans is a medical sign characterised by brown-to-black, poorly defined, velvety hyperpigmentation of the skin. It is usually found in body folds, such as the posterior and lateral folds of the neck, the armpits, groin, navel, f ...

sexual dysfunction Sexual dysfunction is difficulty experienced by an individual or partners during any stage of normal sexual activity, including physical pleasure, desire, preference, arousal, or orgasm. The World Health Organization defines sexual dysfunction ...

, and frequent infections. There is also an association between type 2 diabetes and mild hearing loss.

Causes

The development of type 2 diabetes is caused by a combination of lifestyle and genetic factors. While some of these factors are under personal control, such as diet and

, other factors are not, such as increasing age, female sex, and genetics. Obesity is more common in women than men in many parts of Africa. The