type 1 diabetes type 1 diabetes type 1 diabetes (t1d), formerly known as juvenile diabetes, is an autoimmune disease that originates when cells that make insulin (beta cells) are destroyed by the immune system. insulin is a hormone required for the cells to use blood sugar for energy and it helps regulate glucose levels in the bloodstream. before treatment this results in high blood sugar levels in the body. the common symptoms of this elevated blood sugar are frequent urination, increased thirst, increased hunger, weight loss, and other serious complications. additional symptoms may include blurry vision, tiredness, and slow wound healing. symptoms typically develop over a short period of time, often a matter of weeks. type 1 diabetesother namesdiabetes mellitus type 1, insulin-dependent diabetes, juvenile diabetesa blue circle, the symbol for diabetes.pronunciation/daɪəˈbiːtiːz/ specialtyendocrinologysymptomsfrequent urination, increased thirst, increased hunger, weight loss, blurred vision, fatigue and weakness, bed-wetting in children who previously didn't wet the bed during the nightcomplicationsdiabetic ketoacidosis, nonketotic hyperosmolar coma, poor healing, cardiovascular disease, damage to the eyesusual onsetrelatively short period of timedurationlong termcausesbody does not produce enough insulinrisk factorsfamily history, celiac diseasediagnostic methodblood sugar, a1cpreventionunknowntreatmentinsulin, diabetic diet, exercisefrequency~7.5% of diabetes cases the cause of type 1 diabetes is unknown, but it is believed to involve a combination of genetic and environmental factors. the underlying mechanism involves an autoimmune destruction of the insulin-producing beta cells in the pancreas. diabetes is diagnosed by testing the level of sugar or glycated hemoglobin (hba1c) in the blood. type 1 diabetes can be distinguished from type 2 by testing for the presence of autoantibodies. there is no known way to prevent type 1 diabetes. treatment with insulin is required for survival. insulin therapy is usually given by injection just under the skin but can also be delivered by an insulin pump. a diabetic diet and exercise are important parts of management. if left untreated, diabetes can cause many complications. complications of relatively rapid onset include diabetic ketoacidosis and nonketotic hyperosmolar coma. long-term complications include heart disease, stroke, kidney failure, foot ulcers and damage to the eyes. furthermore, since insulin lowers blood sugar levels, complications may arise from low blood sugar if more insulin is taken than necessary. type 1 diabetes makes up an estimated 5–10% of all diabetes cases. the number of people affected globally is unknown, although it is estimated that about 80,000 children develop the disease each year. within the united states the number of people affected is estimated at one to three million. rates of disease vary widely, with approximately one new case per 100,000 per year in east asia and latin america and around 30 new cases per 100,000 per year in scandinavia and kuwait. it typically begins in children and young adults. signs and symptoms overview of the most significant symptoms of diabetes type 1 diabetes begins suddenly, typically in childhood or adolescence. the major sign of type 1 diabetes is very high blood sugar, which typically manifests in children as a few days to weeks of polyuria (increased urination), polydipsia (increased thirst), and weight loss. children may also experience increased appetite, blurred vision, bedwetting, recurrent skin infections, candidiasis of the perineum, irritability, and performance issues at school. adults with type 1 diabetes tend to have more varied symptoms that come on over months rather than days to weeks. prolonged lack of insulin can also result in diabetic ketoacidosis, characterized by persistent fatigue, dry or flushed skin, abdominal pain, nausea or vomiting, confusion, trouble breathing, and a fruity breath odor. blood and urine tests reveal unusually high glucose and ketones in the blood and urine. untreated ketoacidosis can rapidly progress to loss of consciousness, coma, and death. the percentage of children whose type 1 diabetes begins with an episode of diabetic ketoacidosis varies widely by geography, as low as 15% in parts of europe and north america, and as high as 80% in the developing world. cause type 1 diabetes is caused by the destruction of β-cells – the only cells in the body that produce insulin – and the consequent progressive insulin deficiency. without insulin, the body is unable to respond effectively to increases in blood sugar. due to this, people with diabetes have persistent hyperglycemia. in 70–90% of cases, β-cells are destroyed by someone's own immune system, for reasons that are not entirely clear. the best-studied components of this autoimmune response are β-cell-targeted antibodies that begin to develop in the months or years before symptoms arise. typically someone will first develop antibodies against insulin or the protein gad65, followed eventually by antibodies against the proteins ia-2, ia-2β, and/or znt8. people with more of these antibodies, and who develop them earlier in life, are at higher risk for developing symptomatic type 1 diabetes. the trigger for the development of these antibodies remains unclear. a number of explanatory theories have been put forward, and the cause may involve genetic susceptibility, a diabetogenic trigger, and/or exposure to an antigen. the remaining 10–30% of type 1 diabetics have β-cell destruction but no sign of autoimmunity; this is called idiopathic type 1 diabetes and its cause is unknown. environmental various environmental risks have been studied in an attempt to understand what triggers β-cell autoimmunity. many aspects of environment and life history are associated with slight increases in type 1 diabetes risk, however the connection between each risk and diabetes often remains unclear. type 1 diabetes risk is slightly higher for children whose mothers are obese or older than 35, or for children born by caesarean section. similarly, a child's weight gain in the first year of life, total weight, and bmi are associated with slightly increased type 1 diabetes risk. some dietary habits have also been associated with type 1 diabetes risk, namely consumption of cow's milk and dietary sugar intake. animal studies and some large human studies have found small associations between type 1 diabetes risk and intake of gluten or dietary fiber; however, other large human studies have found no such association. many potential environmental triggers have been investigated in large human studies and found to be unassociated with type 1 diabetes risk including duration of breastfeeding, time of introduction of cow milk into the diet, vitamin d consumption, blood levels of active vitamin d, and maternal intake of omega-3 fatty acids. a longstanding hypothesis for an environmental trigger is that some viral infection early in life contributes to type 1 diabetes development. much of this work has focused on enteroviruses, with some studies finding slight associations with type 1 diabetes, and others finding none. large human studies have searched for, but not yet found an association between type 1 diabetes and various other viral infections, including infections of the mother during pregnancy. conversely, some have postulated that reduced exposure to pathogens in the developed world increases the risk of autoimmune diseases, often called the hygiene hypothesis. various studies of hygiene-related factors – including household crowding, daycare attendance, population density, childhood vaccinations, antihelminth medication, and antibiotic usage during early life or pregnancy – show no association with type 1 diabetes. genetics type 1 diabetes is partially caused by genetics, and family members of type 1 diabetics have a higher risk of developing the disease themselves. in the general population, the risk of developing type 1 diabetes is around 1 in 250. for someone whose parent has type 1 diabetes, the risk rises to 1–9%. if a sibling has type 1 diabetes, the risk is 6–7%. if someone's identical twin has type 1 diabetes, they have a 30–70% risk of developing it themselves. about half of the disease's heritability is due to variations in three hla class ii genes involved in antigen presentation: hla-drb1, hla-dqa1, and hla-dqb1. the variation patterns associated with increased risk of type 1 diabetes are called hla-dr3 and hla-dr4-hla-dq8, and are common in people of european descent. a pattern associated with reduced risk of type 1 diabetes is called hla-dr15-hla-dq6. large genome-wide association studies have identified dozens of other genes associated with type 1 diabetes risk, mostly genes involved in the immune system. chemicals and drugs some medicines can reduce insulin production or damage β cells, resulting in disease that resembles type 1 diabetes. the antiviral drug didanosine triggers pancreas inflammation in 5 to 10% of those who take it, sometimes causing lasting β-cell damage. similarly, up to 5% of those who take the anti-protozoal drug pentamidine experience β-cell destruction and diabetes. several other drugs cause diabetes by reversibly reducing insulin secretion, namely statins (which may also damage β cells), the post-transplant immunosuppressants cyclosporin a and tacrolimus, the leukemia drug l-asparaginase, and the antibiotic gatifloxicin. pyrinuron (vacor), a rodenticide introduced in the united states in 1976, selectively destroys pancreatic beta cells, resulting in type 1 diabetes after accidental poisoning. pyrinuron was withdrawn from the u.s. market in 1979. cancer immunotherapy drugs have also destroyed pancreatic beta cells, such as opdivo among others. diagnosis diabetes is typically diagnosed by a blood test showing unusually high blood sugar. the world health organization defines diabetes as blood sugar levels at or above 7.0 mmol/l (126 mg/dl) after fasting for at least eight hours, or a glucose level at or above 11.1 mmol/l (200 mg/dl) two hours after an oral glucose tolerance test. the american diabetes association additionally recommends a diagnosis of diabetes for anyone with symptoms of hyperglycemia and blood sugar at any time at or above 11.1 mmol/l, or glycated hemoglobin (hemoglobin a1c) levels at or above 48 mmol/mol. once a diagnosis of diabetes is established, type 1 diabetes is distinguished from other types by a blood test for the presence of autoantibodies that target various components of the beta cell. the most commonly available tests detect antibodies against glutamic acid decarboxylase, the beta cell cytoplasm, or insulin, each of which are targeted by antibodies in around 80% of type 1 diabetics. some healthcare providers also have access to tests for antibodies targeting the beta cell proteins ia-2 and znt8; these antibodies are present in around 58% and 80% of type 1 diabetics respectively. some also test for c-peptide, a byproduct of insulin synthesis. very low c-peptide levels are suggestive of type 1 diabetes. management further information: diabetes management the mainstay of type 1 diabetes treatment is the regular injection of insulin to manage hyperglycemia. injections of insulin – via subcutaneous injection using either a syringe or an insulin pump – are necessary multiple times per day, adjusting dosages to account for food intake, blood glucose levels and physical activity. the goal of treatment is to maintain blood sugar in a normal range – 80–130 mg/dl before a meal; <180 mg/dl after – as often as possible. to achieve this, people with diabetes often monitor their blood glucose levels at home. around 83% of type 1 diabetics monitor their blood glucose by capillary blood testing – pricking the finger to draw a drop of blood, and determining blood glucose with a glucose meter. the american diabetes association recommends testing blood glucose around 6–10 times per day: before each meal, before exercise, at bedtime, occasionally after a meal, and any time someone feels the symptoms of hypoglycemia. around 17% of people with type 1 diabetes use a continuous glucose monitor, a device with a sensor under the skin that constantly measures glucose levels and communicates those levels to an external device. continuous glucose monitoring is associated with better blood sugar control than capillary blood testing alone; however, continuous glucose monitoring tends to be substantially more expensive. healthcare providers can also monitor someone's hemoglobin a1c levels which reflect the average blood sugar over the last three months. the american diabetes association recommends a goal of keeping hemoglobin a1c levels under 7% for most adults and 7.5% for children. the goal of insulin therapy is to mimic normal pancreatic insulin secretion: low levels of insulin constantly present to support basic metabolism, plus the two-phase secretion of additional insulin in response to high blood sugar – an initial spike in secreted insulin, then an extended phase with continued insulin secretion. this is accomplished by combining different insulin preparations that act with differing speeds and durations. the standard of care for type 1 diabetes is a bolus of rapid-acting insulin 10–15 minutes before each meal or snacks, and as-needed to correct hyperglycemia. in addition, constant low levels of insulin are achieved