Type 2 diabetes
[1] In type 1 diabetes, there is a lower total level of insulin to control blood glucose, due to an autoimmune-induced loss of insulin-producing beta cells in the pancreas.[3] Type 2 diabetes is largely preventable by staying at a normal weight, exercising regularly, and eating a healthy diet (high in fruits and vegetables and low in sugar and saturated fat).[11][18] Typically, it begins in middle or older age,[6] although rates of type 2 diabetes are increasing in young people.[24] Other symptoms that are commonly present at diagnosis include a history of blurred vision, itchiness, peripheral neuropathy, recurrent vaginal infections, and fatigue.[10] In the developed world, and increasingly elsewhere, type 2 diabetes is the largest cause of nontraumatic blindness and kidney failure.[28] Other complications include hyperpigmentation of skin (acanthosis nigricans), sexual dysfunction, diabetic ketoacidosis, and frequent infections.[35] Lifestyle factors are important to the development of type 2 diabetes, including obesity and being overweight (defined by a body mass index of greater than 25), lack of physical activity, poor diet, psychological stress, and urbanization.[38] Laboratory studies have linked short-term sleep deprivations to changes in glucose metabolism, nervous system activity, or hormonal factors that may lead to diabetes.[13] Other potentially important mechanisms associated with type 2 diabetes and insulin resistance include: increased breakdown of lipids within fat cells, resistance to and lack of incretin, high glucagon levels in the blood, increased retention of salt and water by the kidneys, and inappropriate regulation of metabolism by the central nervous system.Effects of intracellular lipid metabolism and ATP production in liver and muscle cells may contribute to insulin resistance.[62] The World Health Organization definition of diabetes (both type 1 and type 2) is for a single raised glucose reading with symptoms, otherwise raised values on two occasions, of either:[65] A random blood sugar of greater than 11.1 mmol/L (200 mg/dL) in association with typical symptoms[24] or a glycated hemoglobin (HbA1c) of ≥ 48 mmol/mol (≥ 6.5 DCCT %) is another method of diagnosing diabetes.[73] The United States Preventive Services Task Force (USPSTF) recommended in 2021 screening for type 2 diabetes in adults aged 35 to 70 years old who are overweight (i.e. BMI over 25) or have obesity.[68] ADA also recommends screening in adults of all ages with a BMI over 25 (or over 23 in Asian Americans) with another risk factor: first-degree relative with diabetes, ethnicity at high risk for diabetes, blood pressure ≥130/80 mmHg or on therapy for hypertension, history of cardiovascular disease, physical inactivity, polycystic ovary syndrome or severe obesity.[74][75] In the UK, NICE guidelines suggest taking action to prevent diabetes for people with a body mass index (BMI) of 30 or more.[76] A study based on a large sample of people in England suggest even lower BMIs for certain ethnic groups for the start of prevention, for example 24 in South Asian and 21 in Bangladeshi populations.[89] In those with prediabetes, diet in combination with physical activity delays or reduces the risk of type 2 diabetes, according to a 2017 Cochrane review.[80] In those with prediabetes, metformin may delay or reduce the risk of developing type 2 diabetes compared to diet and exercise or a placebo intervention, but not compared to intensive diet and exercise, and there was not enough data on outcomes such as mortality and diabetic complications and health-related quality of life, according to a 2019 Cochrane review.[92] In those with prediabetes, there was insufficient data to draw any conclusions on whether SGLT2 inhibitors may delay or reduce the risk of developing type 2 diabetes, according to a 2016 Cochrane review.[93] Management of type 2 diabetes focuses on lifestyle interventions, lowering other cardiovascular risk factors, and maintaining blood glucose levels in the normal range.[95] Managing other cardiovascular risk factors, such as hypertension, high cholesterol, and microalbuminuria, improves a person's life expectancy.[13] There is moderate evidence suggesting that treating gum disease by scaling and root planing results in an improvement in blood sugar levels for people with diabetes.[112][115] A 2021 review showed that consumption of tree nuts (walnuts, almonds, and hazelnuts) reduced fasting blood glucose in diabetic people.[119] Culturally appropriate education may help people with type 2 diabetes control their blood sugar levels for up to 24 months.[24] Many international guidelines recommend blood pressure treatment targets that are lower than 140/90 mmHg for people with diabetes.[143] Sharing their electronic health records with people who have type 2 diabetes helps them to reduce their blood sugar levels.[10] Some ethnic groups such as South Asians, Pacific Islanders, Latinos, and Native Americans are at particularly high risk of developing type 2 diabetes.[18] Traditionally considered a disease of adults, type 2 diabetes is increasingly diagnosed in children in parallel with rising obesity rates.[22] Effective treatment was not developed until the early part of the 20th century when the Canadians Frederick Banting and Charles Best discovered insulin in 1921 and 1922.[26][160] It uses a computer algorithm to analyse data from anonymised electronic patient records and produces a score based on 34 indicators.[161][160] In April 2024 scientists reported the first case of reversion of type 2 diabetes by use of stem cells in a 59-year-old man treated in 2021 who has since remain insulin-free.
SpecialtyEndocrinologySymptomsIncreased thirstfrequent urinationweight lossincreased hungerComplicationsHyperosmolar hyperglycemic statediabetic ketoacidosisheart diseasestrokediabetic retinopathykidney failureamputationsObesitygeneticsDiagnostic methodexercisingDietary changesmetforminbariatric surgeryPrognosislife expectancydiabetes mellitushigh blood sugarinsulin resistanceinsulinfatiguepins and needlesblindnessketoacidosislack of exercisegeneticallydiabetestype 1 diabetesgestational diabetesautoimmunebeta cellspancreasfasting plasma glucoseoral glucose tolerance testglycated hemoglobinfruitsvegetablessaturated fatexerciseinsulin injectionscontinuous glucose monitorpolyuriapolydipsiapolyphagiablurred visionitchinessperipheral neuropathyvaginal infectionsloss of tastedecreased level of consciousnesslow blood pressureComplications of diabetesischemic heart diseasehospitalizationscognitive dysfunctiondementiaAlzheimer's diseasevascular dementiaacanthosis nigricanssexual dysfunctionhearing lossGenerous consumption of alcoholnutritionalLifestyle causes of type 2 diabetesoverweightbody mass indexlack of physical activitypsychological stressurbanizationPima IndiansPacific Islanderswaist–hip ratiotrans fatty acidspolyunsaturatedmonounsaturated fatwhite riceSedentary lifestylePersistent organic pollutantsGenetic causes of type 2 diabetesEpigenetics of diabetes type 2inheritedsingle nucleotide polymorphismsTCF7L2allelebeta cellmonogenicmaturity onset diabetes of the youngDonohue syndromeRabson–Mendenhall syndromeEpigeneticglucocorticoidsthiazidesbeta blockersatypical antipsychoticsstatinsacromegalyCushing's syndromehyperthyroidismpheochromocytomacancersglucagonomasTestosterone deficiencyEating disordersbulimia nervosaanorexia nervosaDisposition metricsglucoselipidsfat cellsincretinglucagonkidneyscentral nervous systemdisposition indexImpaired fasting glycaemiaImpaired glucose toleranceWorld Health Organizationglucose tolerance test