This is specific to type 2 diabetes. It occurs when insulin is produced normally in the pancreas, but the body is still unable move glucose into the cells for fuel. At first, the pancreas will create more insulin to overcome the body’s resistance. Eventually the cells “wear out.” At that point the body slows insulin production, leaving too much glucose in the blood. This is known as prediabetes. A person with prediabetes has a blood sugar level higher than normal but not high enough for a diagnosis of diabetes. Unless tested, the person may not be aware, as there are no clear symptoms. Type 2 diabetes occurs as insulin production continues to decrease and resistance increases.

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.
Type 1 diabetes has some connection to your family genes, but that doesn't mean you'll get it if one of your parents had it. "Since not all identical twins get diabetes, we do think that exposure to an additional environmental factor may trigger an immune response that ultimately causes destruction of the insulin-producing cells of the pancreas," says Dr. Sarah R. Rettinger, an endocrinologist with Providence Saint John's Health Center in Santa Monica, California.
There are two major types of diabetes, called type 1 and type 2. Type 1 diabetes was also formerly called insulin dependent diabetes mellitus (IDDM), or juvenile-onset diabetes mellitus. In type 1 diabetes, the pancreas undergoes an autoimmune attack by the body itself, and is rendered incapable of making insulin. Abnormal antibodies have been found in the majority of patients with type 1 diabetes. Antibodies are proteins in the blood that are part of the body's immune system. The patient with type 1 diabetes must rely on insulin medication for survival.
Can type 2 diabetes be cured? In the early stages of type 2 diabetes, it is possible to manage the diabetes to a level where symptoms go away and A1c reaches a normal level – this effectively “reverses” the progression of type 2 diabetes. According to research from Newcastle University, major weight loss can return insulin secretion to normal in people who had type 2 diabetes for four years or less. Indeed, it is commonly believed that significant weight loss and building muscle mass is the best way to reverse type 2 diabetes progression. However, it is important to note that reversing diabetes progression is not the same as curing type 2 diabetes – people still need to monitor their weight, diet, and exercise to ensure that type 2 diabetes does not progress. For many people who have had type 2 diabetes for a longer time, the damage to the beta cells progresses to the point at which it will never again be possible to make enough insulin to correctly control blood glucose, even with dramatic weight loss. But even in these people, weight loss is likely the best way to reduce the threat of complications.

 Type 1 diabetes mellitus is a chronic metabolic syndrome defined by an inability to produce insulin, a hormone which lowers blood sugar. This leads to inappropriate hyperglycaemia (increased blood sugar levels) and deranged metabolism of carbohydrates, fats and proteins. Insulin is normally produced in the pancreas, a glandular organ involved in the production of digestive enzymes and hormones such as insulin and glucagon. These functions are carried out in the exocrine and endocrine (Islets of Langerhans) pancreas respectively.
As of 2016, 422 million people have diabetes worldwide,[101] up from an estimated 382 million people in 2013[17] and from 108 million in 1980.[101] Accounting for the shifting age structure of the global population, the prevalence of diabetes is 8.5% among adults, nearly double the rate of 4.7% in 1980.[101] Type 2 makes up about 90% of the cases.[16][18] Some data indicate rates are roughly equal in women and men,[18] but male excess in diabetes has been found in many populations with higher type 2 incidence, possibly due to sex-related differences in insulin sensitivity, consequences of obesity and regional body fat deposition, and other contributing factors such as high blood pressure, tobacco smoking, and alcohol intake.[102][103]
The relationship between type 2 diabetes and the main modifiable risk factors (excess weight, unhealthy diet, physical inactivity and tobacco use) is similar in all regions of the world. There is growing evidence that the underlying determinants of diabetes are a reflection of the major forces driving social, economic and cultural change: globalization, urbanization, population aging, and the general health policy environment.[74]
The word mellitus (/məˈlaɪtəs/ or /ˈmɛlɪtəs/) comes from the classical Latin word mellītus, meaning "mellite"[114] (i.e. sweetened with honey;[114] honey-sweet[115]). The Latin word comes from mell-, which comes from mel, meaning "honey";[114][115] sweetness;[115] pleasant thing,[115] and the suffix -ītus,[114] whose meaning is the same as that of the English suffix "-ite".[116] It was Thomas Willis who in 1675 added "mellitus" to the word "diabetes" as a designation for the disease, when he noticed the urine of a diabetic had a sweet taste (glycosuria). This sweet taste had been noticed in urine by the ancient Greeks, Chinese, Egyptians, Indians, and Persians.
Diabetes mellitus is a diagnostic term for a group of disorders characterized by abnormal glucose homeostasis resulting in elevated blood sugar. It is among the most common of chronic disorders, affecting up to 5–10% of the adult population of the Western world. The prevalence of diabetes is increasing dramatically; it has been estimated that the worldwide prevalence will increase by more than 50% between the years 2000 and 2030 (Wild et al., 2004). It is clearly established that diabetes mellitus is not a single disease, but a genetically heterogeneous group of disorders that share glucose intolerance in common. The concept of genetic heterogeneity (i.e. that different genetic and/or environmental etiologic factors can result in similar phenotypes) has significantly altered the genetic analysis of this common disorder.
Excessive hunger goes hand-in-hand with fatigue and cell starvation. Because the cells are resistant to the body's insulin, glucose remains in the blood. The cells are then unable to gain access to glucose, which can trigger hunger hormones that tell the brain that you are hungry. Excessive eating can complicate things further by causing blood sugars to increase.
observations The onset of type 1 diabetes mellitus is sudden in children. Type 2 diabetes often begins insidiously. Characteristically the course is progressive and includes polyuria, polydipsia, weight loss, polyphagia, hyperglycemia, and glycosuria. The eyes, kidneys, nervous system, skin, and circulatory system may be affected by the long-term complications of either type of diabetes; infections are common; and atherosclerosis often develops. In type 1 diabetes mellitus, when no endogenous insulin is being secreted, ketoacidosis is a constant danger. The diagnosis is confirmed by fasting plasma glucose and history.
For example, the environmental trigger may be a virus or chemical toxin that upsets the normal function of the immune system. This may lead to the body’s immune system attacking itself. The normal beta cells in the pancreas may be attacked and destroyed. When approximately 90% of the beta cells are destroyed, symptoms of diabetes mellitus begin to appear. The exact cause and sequence is not fully understood but investigation and research into the disease continues.
People usually develop type 2 diabetes after the age of 40 years, although people of South Asian origin are at an increased risk of the condition and may develop diabetes from the age of 25 onwards. The condition is also becoming increasingly common among children and adolescents across all populations. Type 2 diabetes often develops as a result of overweight, obesity and lack of physical activity and diabetes prevalence is on the rise worldwide as these problems become more widespread.
Blood travels throughout your body, and when too much glucose (sugar) is present, it disrupts the normal environment that the organ systems of your body function within. In turn, your body starts to exhibit signs that things are not working properly inside—those are the symptoms of diabetes people sometimes experience. If this problem—caused by a variety of factors—is left untreated, it can lead to a number of damaging complications such as heart attacks, strokes, blindness, kidney failure, and blood vessel disease that may require an amputation, nerve damage, and impotence in men.
What is type 2 diabetes and prediabetes? Behind type 2 diabetes is a disease where the body’s cells have trouble responding to insulin – this is called insulin resistance. Insulin is a hormone needed to store the energy found in food into the body’s cells. In prediabetes, insulin resistance starts growing and the beta cells in the pancreas that release insulin will try to make even more insulin to make up for the body’s insensitivity. This can go on for a long time without any symptoms. Over time, though, the beta cells in the pancreas will fatigue and will no longer be able to produce enough insulin – this is called “beta burnout.” Once there is not enough insulin, blood sugars will start to rise above normal. Prediabetes causes people to have higher-than-normal blood sugars (and an increased risk for heart disease and stroke). Left unnoticed or untreated, blood sugars continue to worsen and many people progress to type 2 diabetes. After a while, so many of the beta cells have been damaged that diabetes becomes an irreversible condition. 

Type 2 diabetes can be prevented with lifestyle changes. People who are overweight and lose as little as 7 percent of their body weight and who increase physical activity (for example, walking 30 minutes per day) can decrease their risk of diabetes mellitus by more than 50%. Metformin and acarbose, drugs that are used to treat diabetes, may reduce the risk of diabetes in people with impaired glucose regulation.
Many older people have difficulty following a healthy, balanced diet that can control blood glucose levels and weight. Changing long-held food preferences and dietary habits may be hard. Some older people have other disorders that can be affected by diet and may not understand how to integrate the dietary recommendations for their various disorders.
Endocrinology A chronic condition which affects ±10% of the general population, characterized by ↑ serum glucose and a relative or absolute ↓ in pancreatic insulin production, or ↓ tissue responsiveness to insulin; if not properly controlled, the excess glucose damages blood vessels of the eyes, kidneys, nerves, heart Types Insulin dependent–type I and non-insulin dependent–type II diabetes Symptoms type 1 DM is associated with ↑ urine output, thirst, fatigue, and weight loss (despite an ↑ appetite), N&V; type 2 DM is associated with, in addition, non-healing ulcers, oral and bladder infections, blurred vision, paresthesias in the hands and feet, and itching Cardiovascular MI, stoke Eyes Retinal damage, blindness Legs/feet Nonhealing ulcers, cuts leading to gangrene and amputation Kidneys HTN, renal failure Neurology Paresthesias, neuropathy Diagnosis Serum glucose above cut-off points after meals or when fasting; once therapy is begun, serum levels of glycosylated Hb are measured periodically to assess adequacy of glucose control Management Therapy reflects type of DM; metformin and triglitazone have equal and additive effects on glycemic control Prognosis A function of stringency of glucose control and presence of complications. See ABCD Trial, Brittle diabetes, Bronze diabetes, Chemical diabetes, Gestational diabetes, Insulin-dependent diabetes, Metformin, MODY diabetes, Nephrogenic diabetes insipidus, Non-insulin-dependent diabetes mellitus, Pseudodiabetes, Secondary diabetes, Starvation diabetes, Troglitazone.
Home blood sugar (glucose) testing is an important part of controlling blood sugar. One important goal of diabetes treatment is to keep the blood glucose levels near the normal range of 70 to 120 mg/dl before meals and under 140 mg/dl at two hours after eating. Blood glucose levels are usually tested before and after meals, and at bedtime. The blood sugar level is typically determined by pricking a fingertip with a lancing device and applying the blood to a glucose meter, which reads the value. There are many meters on the market, for example, Accu-Check Advantage, One Touch Ultra, Sure Step and Freestyle. Each meter has its own advantages and disadvantages (some use less blood, some have a larger digital readout, some take a shorter time to give you results, etc.). The test results are then used to help patients make adjustments in medications, diets, and physical activities.
Scientists have done studies of twins to help estimate how important genes are in determining one's risk of developing diabetes. Identical twins have identical genes and thus the same genetic risk for a disease. Research has found that if one identical twin has type 1 diabetes, the chance that the other twin will get the disease is roughly 40 or 50 percent. For type 2 diabetes, that risk goes up to about 80 or 90 percent. This might suggest that genes play a bigger role in type 2 than in type 1, but that isn't necessarily so. Type 2 is far more common in the general population than type 1, which means that regardless of genetics both twins are more likely to develop type 2 diabetes.
Diabetes can also result from other hormonal disturbances, such as excessive growth hormone production (acromegaly) and Cushing's syndrome. In acromegaly, a pituitary gland tumor at the base of the brain causes excessive production of growth hormone, leading to hyperglycemia. In Cushing's syndrome, the adrenal glands produce an excess of cortisol, which promotes blood sugar elevation.

Blood travels throughout your body, and when too much glucose (sugar) is present, it disrupts the normal environment that the organ systems of your body function within. In turn, your body starts to exhibit signs that things are not working properly inside—those are the symptoms of diabetes people sometimes experience. If this problem—caused by a variety of factors—is left untreated, it can lead to a number of damaging complications such as heart attacks, strokes, blindness, kidney failure, and blood vessel disease that may require an amputation, nerve damage, and impotence in men.

Type 1 diabetes has some connection to your family genes, but that doesn't mean you'll get it if one of your parents had it. "Since not all identical twins get diabetes, we do think that exposure to an additional environmental factor may trigger an immune response that ultimately causes destruction of the insulin-producing cells of the pancreas," says Dr. Sarah R. Rettinger, an endocrinologist with Providence Saint John's Health Center in Santa Monica, California.
George P Chrousos, MD, FAAP, MACP, MACE, FRCP(London) is a member of the following medical societies: American Academy of Pediatrics, American College of Physicians, American Pediatric Society, American Society for Clinical Investigation, Association of American Physicians, Endocrine Society, Pediatric Endocrine Society, Society for Pediatric Research, American College of Endocrinology
Type 1 diabetes occurs when the immune system attacks and destroys the insulin-producing cells in the pancreas (the beta cells). As a result, the body is left without enough insulin to function normally (i.e. it becomes insulin deficient). This is called an autoimmune reaction, because the body attacks itself and produces antibodies to its own insulin-producing cells, thereby destroying them.
An article published in November 2012 in the journal Global Public Health found that countries with more access to HFCS tended to have higher rates of the disease. Though it’s likely that these countries’ overall eating habits play a role in their populations’ diabetes risk, a study published in February 2013 in the journal PLoS One found limiting access to HFCS in particular may help reduce rates of the diagnosis.
Can type 2 diabetes be cured? In the early stages of type 2 diabetes, it is possible to manage the diabetes to a level where symptoms go away and A1c reaches a normal level – this effectively “reverses” the progression of type 2 diabetes. According to research from Newcastle University, major weight loss can return insulin secretion to normal in people who had type 2 diabetes for four years or less. Indeed, it is commonly believed that significant weight loss and building muscle mass is the best way to reverse type 2 diabetes progression. However, it is important to note that reversing diabetes progression is not the same as curing type 2 diabetes – people still need to monitor their weight, diet, and exercise to ensure that type 2 diabetes does not progress. For many people who have had type 2 diabetes for a longer time, the damage to the beta cells progresses to the point at which it will never again be possible to make enough insulin to correctly control blood glucose, even with dramatic weight loss. But even in these people, weight loss is likely the best way to reduce the threat of complications.
Most cases of diabetes involve many genes, with each being a small contributor to an increased probability of becoming a type 2 diabetic.[10] If one identical twin has diabetes, the chance of the other developing diabetes within his lifetime is greater than 90%, while the rate for nonidentical siblings is 25–50%.[13] As of 2011, more than 36 genes had been found that contribute to the risk of type 2 diabetes.[37] All of these genes together still only account for 10% of the total heritable component of the disease.[37] The TCF7L2 allele, for example, increases the risk of developing diabetes by 1.5 times and is the greatest risk of the common genetic variants.[13] Most of the genes linked to diabetes are involved in beta cell functions.[13]
Finally, modern society should probably shoulder at least some of the blame for the type 2 diabetes epidemic. Access to cheap, calorie-laden foods may even influence type 2 risk beyond simply their effects on body weight; the stuff that is in processed foods, like high-fructose corn syrup, could alter the body's chemistry or gut microbes in a way that affects health. Add to that the fact that most Americans are sedentary, spending their time sitting in cubicles, driving in cars, playing video games, or watching television. The lack of exercise, plus the abundance of unhealthy foods, cultivates a fertile breeding ground for diabetes.
Type 2 diabetes is believed to have a strong genetic link, meaning that it tends to run in families. Several genes are being studied that may be related to the cause of type 2 diabetes. If you have any of the following type 2 diabetes risk factors, it’s important to ask your doctor about a diabetes test. With a proper diabetes diet and healthy lifestyle habits, along with diabetes medication, if necessary, you can manage type 2 diabetes just like you manage other areas of your life. Be sure to continue seeking the latest information on type 2 diabetes as you become your own health advocate.
A 2009 study shows how genetic information may shed light on the environment-gene interactions that lead to type 1. In the study, researchers found that one of the type 1 genes mediates the immune system's response to viruses. This finding supported the longtime hypothesis that a virus may somehow make the immune system attack the insulin-producing cells in the pancreas in people who are genetically susceptible to developing diabetes.

Type 2 diabetes mellitus (non–insulin-dependent diabetes mellitus [NIDDM]) is a heterogeneous disorder. Most patients with type 2 diabetes mellitus have insulin resistance, and their beta cells lack the ability to overcome this resistance. [6] Although this form of diabetes was previously uncommon in children, in some countries, 20% or more of new patients with diabetes in childhood and adolescence have type 2 diabetes mellitus, a change associated with increased rates of obesity. Other patients may have inherited disorders of insulin release, leading to maturity onset diabetes of the young (MODY) or congenital diabetes. [7, 8, 9] This topic addresses only type 1 diabetes mellitus. (See Etiology and Epidemiology.)
Most people with diabetes should keep a record of their blood glucose levels and report them to their doctor or nurse for advice in adjusting the dose of insulin or the oral antihyperglycemic drug. Many people can learn to adjust the insulin dose on their own as necessary. Some people who have mild or early type 2 diabetes that is well-controlled with one or two drugs may be able to monitor their fingerstick glucose levels relatively infrequently.

Diabetes that's triggered by pregnancy is called gestational diabetes (pregnancy, to some degree, leads to insulin resistance). It is often diagnosed in middle or late pregnancy. Because high blood sugar levels in a mother are circulated through the placenta to the baby, gestational diabetes must be controlled to protect the baby's growth and development.


The good news is that behavior still seems to help shape whether someone with the genetic disposition actually develops type 2—and that changes in diet and exercise can sometimes be enough to ward off the disease. "People sometimes have the misconception that if we say something is genetic, then they can't do anything about preventing diabetes and its complications," says Hanis. But he notes that in a landmark study, lifestyle interventions prevented or delayed type 2 in nearly 60 percent of people at high risk. "If we focus on changing the environment, we can prevent diabetes," he says. "As we understand the genetics, we can prevent more of it."

The relationship between type 2 diabetes and the main modifiable risk factors (excess weight, unhealthy diet, physical inactivity and tobacco use) is similar in all regions of the world. There is growing evidence that the underlying determinants of diabetes are a reflection of the major forces driving social, economic and cultural change: globalization, urbanization, population aging, and the general health policy environment.[74]
The term "diabetes" or "to pass through" was first used in 230 BCE by the Greek Apollonius of Memphis.[108] The disease was considered rare during the time of the Roman empire, with Galen commenting he had only seen two cases during his career.[108] This is possibly due to the diet and lifestyle of the ancients, or because the clinical symptoms were observed during the advanced stage of the disease. Galen named the disease "diarrhea of the urine" (diarrhea urinosa).[110]
Though not routinely used any longer, the oral glucose tolerance test (OGTT) is a gold standard for making the diagnosis of type 2 diabetes. It is still commonly used for diagnosing gestational diabetes and in conditions of pre-diabetes, such as polycystic ovary syndrome. With an oral glucose tolerance test, the person fasts overnight (at least eight but not more than 16 hours). Then first, the fasting plasma glucose is tested. After this test, the person receives an oral dose (75 grams) of glucose. There are several methods employed by obstetricians to do this test, but the one described here is standard. Usually, the glucose is in a sweet-tasting liquid that the person drinks. Blood samples are taken at specific intervals to measure the blood glucose.
Type 2 diabetes is partly preventable by staying a normal weight, exercising regularly, and eating properly.[1] Treatment involves exercise and dietary changes.[1] If blood sugar levels are not adequately lowered, the medication metformin is typically recommended.[7][14] Many people may eventually also require insulin injections.[9] In those on insulin, routinely checking blood sugar levels is advised; however, this may not be needed in those taking pills.[15] Bariatric surgery often improves diabetes in those who are obese.[8][16]
Hypoglycemia, or low blood sugar, can be caused by too much insulin, too little food (or eating too late to coincide with the action of the insulin), alcohol consumption, or increased exercise. A patient with symptoms of hypoglycemia may be hungry, cranky, confused, and tired. The patient may become sweaty and shaky. Left untreated, the patient can lose consciousness or have a seizure. This condition is sometimes called an insulin reaction and should be treated by giving the patient something sweet to eat or drink like a candy, sugar cubes, juice, or another high sugar snack.
In an otherwise healthy individual, blood glucose levels usually do not rise above 180 mg/dL (9 mmol/L). In a child with diabetes, blood sugar levels rise if insulin is insufficient for a given glucose load. The renal threshold for glucose reabsorption is exceeded when blood glucose levels exceed 180 mg/dL (10 mmol/L), causing glycosuria with the typical symptoms of polyuria and polydipsia. (See Pathophysiology, Clinical, and Treatment.)
Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.
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