A metabolic disease in which carbohydrate use is reduced and that of lipid and protein enhanced; it is caused by an absolute or relative deficiency of insulin and is characterized, in more severe cases, by chronic hyperglycemia, glycosuria, water and electrolyte loss, ketoacidosis, and coma; long-term complications include neuropathy, retinopathy, nephropathy, generalized degenerative changes in large and small blood vessels, and increased susceptibility to infection.
According to the American Diabetes Association, a child has a 1 in 7 risk of getting type 2 diabetes if his/her parent was diagnosed with type 2 diabetes before the age of 50, and a 1 in 13 risk of developing it if the parent was diagnosed after the age of 50. To see if you may be at risk for diabetes, consider taking this short and simple Type 2 Diabetes Risk Test from the ADA.
Type 2 diabetes is mainly caused by insulin resistance. This means no matter how much or how little insulin is made, the body can't use it as well as it should. As a result, glucose can't be moved from the blood into cells. Over time, the excess sugar in the blood gradually poisons the pancreas causing it to make less insulin and making it even more difficult to keep blood glucose under control.

Insulin is the hormone responsible for reducing blood sugar. In order for insulin to work, our tissues have to be sensitive to its action; otherwise, tissues become resistant and insulin struggles to clear out sugar from the blood. As insulin resistance sets in, the first organ to stop responding to insulin is the liver, followed by the muscles and eventually fat. How does insulin resistance begin? The root of the problem is our diet.
Symptoms of type 1 diabetes can start quickly, in a matter of weeks. Symptoms of type 2 diabetes often develop slowly—over the course of several years—and can be so mild that you might not even notice them. Many people with type 2 diabetes have no symptoms. Some people do not find out they have the disease until they have diabetes-related health problems, such as blurred vision or heart trouble.
Merck & Co., Inc., Kenilworth, NJ, USA is a global healthcare leader working to help the world be well. From developing new therapies that treat and prevent disease to helping people in need, we are committed to improving health and well-being around the world. The Merck Manual was first published in 1899 as a service to the community. The legacy of this great resource continues as the Merck Manual in the US and Canada and the MSD Manual outside of North America. Learn more about our commitment to Global Medical Knowledge.
Rates of type 2 diabetes have increased markedly since 1960 in parallel with obesity.[17] As of 2015 there were approximately 392 million people diagnosed with the disease compared to around 30 million in 1985.[11][18] Typically it begins in middle or older age,[6] although rates of type 2 diabetes are increasing in young people.[19][20] Type 2 diabetes is associated with a ten-year-shorter life expectancy.[10] Diabetes was one of the first diseases described.[21] The importance of insulin in the disease was determined in the 1920s.[22]
Lose Weight: If you are overweight, losing weight can help your body use insulin. In fact, the American Diabetes Association recommends that people with diabetes lose about 7 percent of their body weight, which should improve the way your body uses insulin and reduces insulin resistance. In addition, weight loss can help lower blood pressure, reduce joint pain, increase energy, and reduce sleep apnea and cholesterol. It can also reduce your risk of other diseases, including heart disease.
People with type 1 diabetes and certain people with type 2 diabetes may use carbohydrate counting or the carbohydrate exchange system to match their insulin dose to the carbohydrate content of their meal. "Counting" the amount of carbohydrate in a meal is used to calculate the amount of insulin the person takes before eating. However, the carbohydrate-to-insulin ratio (the amount of insulin taken for each gram of carbohydrate in the meal) varies for each person, and people with diabetes need to work closely with a dietician who has experience in working with people with diabetes to master the technique. Some experts have advised use of the glycemic index (a measure of the impact of an ingested carbohydrate-containing food on the blood glucose level) to delineate between rapid and slowly metabolized carbohydrates, although there is little evidence to support this approach.

Some risks of the keto diet include low blood sugar, negative medication interactions, and nutrient deficiencies. (People who should avoid the keto diet include those with kidney damage or disease, women who are pregnant or breast-feeding, and those with or at a heightened risk for heart disease due to high blood pressure, high cholesterol, or family history. (40)
To diagnose diabetes, doctors will  take a medical history (ask you about symptoms) and ask for blood and urine samples. Finding protein and sugar in the urine are signs of type 2 diabetes. Increased glucose and triglyceride (a type of lipid or fat) levels in the blood are also common findings. In most cases, blood glucose levels are checked after a person has been fasting for 8 hours.

Regarding age, data shows that for each decade after 40 years of age regardless of weight there is an increase in incidence of diabetes. The prevalence of diabetes in persons 65 years of age and older is around 25%. Type 2 diabetes is also more common in certain ethnic groups. Compared with a 7% prevalence in non-Hispanic Caucasians, the prevalence in Asian Americans is estimated to be 8.0%, in Hispanics 13%, in blacks around 12.3%, and in certain Native American communities 20% to 50%. Finally, diabetes occurs much more frequently in women with a prior history of diabetes that develops during pregnancy (gestational diabetes).
Jump up ^ Santaguida PL, Balion C, Hunt D, Morrison K, Gerstein H, Raina P, Booker L, Yazdi H. "Diagnosis, Prognosis, and Treatment of Impaired Glucose Tolerance and Impaired Fasting Glucose". Summary of Evidence Report/Technology Assessment, No. 128. Agency for Healthcare Research and Quality. Archived from the original on 16 September 2008. Retrieved 20 July 2008.
Awareness about the signs and symptoms and periodic screening especially in the presence of risk factors and warning signs of diabetes, would go a long way in preventing new cases of diabetes by providing an opportunity to intervene at the stage of prediabetes. It is evident that diabetes can be prevented among prediabetic individuals by improvements in physical activity and diet habits. Such strategies will also prevent development of diabetic complications to a great extent. Patient empowerment is vital in diabetes management. This can be done through patient education and sharing information on management and preventive aspects of diabetes.
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]
If you are at increased risk of diabetes, have symptoms of diabetes, or have pre-diabetes (a major warning sign for diabetes), your doctor will check to see if you have diabetes. Your doctor may also check to see if you have diabetes if you are over the age of 45, have a family history of the disease, are overweight, or if you are at increased risk for another reason. The tests used to check for diabetes are the same tests used to check for pre-diabetes.
You have a higher risk of type 2 diabetes if you are older, have obesity, have a family history of diabetes, or do not exercise. Having prediabetes also increases your risk. Prediabetes means that your blood sugar is higher than normal but not high enough to be called diabetes. If you are at risk for type 2 diabetes, you may be able to delay or prevent developing it by making some lifestyle changes.
Diabetes can also be diagnosed if a blood glucose level taken any time of the day without regards to meals is 11.1 mmol/L or higher, plus you have symptoms characteristic of diabetes (e.g., increase thirst, increase urination, unexplained weight loss). A doctor may also examine the eyes for signs of damage to the blood vessels of the retina (back of the eye). Finally, diabetes mellitus is diagnosed if the 3-month cumulative blood sugar average test, known as hemoglobin A1C or glycated hemoglobin, is 6.5% or higher.
Unexplained weight loss can happen for lots of reasons, and diabetes is one of them. Goundan explains that insulin helps your body move sugar from your blood to your cells, so when you have an insulin resistance, you don’t get enough energy into your cells despite all that sugar flowing through your body. “Because you’re unable to get enough energy from sugar, your body burns your own fat and muscle for energy," Kellis says. "Weight loss can be pretty significant, sometimes 10 to 20 pounds."
In Japan, China, and other Asian countries, the transition from traditional carbohydrate-rich (e.g., rice-based) diets to lower-carbohydrate Westernized eating habits emphasizing meats, dairy products, and fried foods has been accompanied by a major increase in diabetes prevalence. Similarly, in the United States, a meat-based (omnivorous) diet is associated with a high prevalence of diabetes, compared with dietary patterns emphasizing plant-derived foods. In the Adventist Health Study-2, after adjusting for differences in body weight, physical activity, and other factors, an omnivorous diet was associated with roughly double the risk of diabetes, compared with a diet omitting animal products.5

Several tests are helpful in identifying DM. These include tests of fasting plasma glucose levels, casual (randomly assessed) glucose levels, or glycosylated hemoglobin levels. Diabetes is currently established if patients have classic diabetic symptoms and if on two occasions fasting glucose levels exceed 126 mg/dL (> 7 mmol/L), random glucose levels exceed 200 mg/dL (11.1 mmol/L), or a 2-hr oral glucose tolerance test is 200 mg/dL or more. A hemoglobin A1c test that is more than two standard deviations above normal (6.5% or greater) is also diagnostic of the disease.

Pre-clinical diabetes refers to the time during which destruction of pancreatic insulin-producing cells is occurring, but symptoms have not yet developed. This period may last for months to years. Normally, 80-90% of the pancreatic beta cells must be destroyed before any symptoms of diabetes develops. During this time, blood tests can identify some immunological markers of pancreatic cell destruction. However, there is currently no known treatment to prevent progression of pre-clinical diabetes to true diabetes mellitus.
The causes of diabetes mellitus are unclear, however, there seem to be both hereditary (genetic factors passed on in families) and environmental factors involved. Research has shown that some people who develop diabetes have common genetic markers. In Type I diabetes, the immune system, the body's defense system against infection, is believed to be triggered by a virus or another microorganism that destroys cells in the pancreas that produce insulin. In Type II diabetes, age, obesity, and family history of diabetes play a role.
6. Polycystic ovary syndrome (PCOS): This is a common cause of female infertility and insulin resistance. It can cause signs and symptoms like irregular periods, acne, thinning scalp hair, and excess hair growth on the face and body. High insulin levels also increase the risk of developing diabetes, and about half of women with PCOS develop diabetes.
Environmental factors are important, because even identical twins have only a 30-60% concordance for type 1 diabetes mellitus and because incidence rates vary in genetically similar populations under different living conditions. [25] No single factor has been identified, but infections and diet are considered the 2 most likely environmental candidates.
The woman’s weight may also play a role. Changing hormone levels and weight gain are part of a healthy pregnancy, but both changes make it more difficult for the body to keep up with its need for insulin. This may lead to gestational diabetes. As pregnancy progresses, the placenta also produces insulin-blocking hormones, which might result in a woman’s blood-glucose levels becoming elevated if there isn’t enough insulin to counter this effect.
Some risks of the keto diet include low blood sugar, negative medication interactions, and nutrient deficiencies. (People who should avoid the keto diet include those with kidney damage or disease, women who are pregnant or breast-feeding, and those with or at a heightened risk for heart disease due to high blood pressure, high cholesterol, or family history. (40)
Diabetes mellitus, or simply diabetes, is a group of diseases in which a person does not produce enough insulin, or because it does not respond to the insulin that is produced. Insulin is a hormone that controls the amount of glucose (sugar) in the blood. Diabetes leads to high blood sugar levels, which can lead to damage of blood vessels, organs, and nerves.
Type 2 diabetes is one of the major degenerative diseases in the Western world today. It happens when your body can’t use insulin properly, or can’t make enough insulin. Insulin is a hormone the assists the body’s cells in utilizing glucose. It also helps the body store extra sugar in fat, liver, and muscle cells. If you don’t have insulin, your body can’t use the sugar in the bloodstream.
Low blood sugar (hypoglycemia), is common in people with type 1 and type 2 DM. Most cases are mild and are not considered medical emergencies. Effects can range from feelings of unease, sweating, trembling, and increased appetite in mild cases to more serious effects such as confusion, changes in behavior such as aggressiveness, seizures, unconsciousness, and (rarely) permanent brain damage or death in severe cases.[24][25] Moderately low blood sugar may easily be mistaken for drunkenness;[26] rapid breathing and sweating, cold, pale skin are characteristic of low blood sugar but not definitive.[27] Mild to moderate cases are self-treated by eating or drinking something high in sugar. Severe cases can lead to unconsciousness and must be treated with intravenous glucose or injections with glucagon.[28]

Diabetes: The differences between types 1 and 2 There are fundamental differences between diabetes type 1 and type 2, including when they might occur, their causes, and how they affect someone's life. Find out here what distinguishes the different forms of the disease, the various symptoms, treatment methods, and how blood tests are interpreted. Read now
The protocol for therapy is determined by the type of diabetes; patients with either type 1 or type 2 must pay attention to their diet and exercise regimens. Insulin therapy may be prescribed for patients with type 2 diabetes as well as any who are dependent on insulin. In most cases, the type 2 diabetes patient can be treated effectively by reducing caloric intake, maintaining target weight, and promoting physical exercise.
Other studies have focused, not on sugar overall but specifically on sodas and other sugar-sweetened beverages. Many have found no significant relationship, apart from sugar’s extra calories that lead to weight gain. For example, the Women’s Health Study,8 the Atherosclerosis Risk in Communities Study,9 the Black Women’s Health Study,10 and the Multi-Ethnic Study of Atherosclerosis found no significant associations between sugar consumption and diabetes risk after adjustment for measures of body weight. Some studies have had mixed results, exonerating sucrose, but indicting glucose and fructose.12,13 And some studies have shown associations between sugar-sweetened beverages and diabetes that persist after adjustment for body weight.14,15

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."


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.

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.

Impaired glucose tolerance (IGT) and impaired fasting glycaemia (IFG) refer to levels of blood glucose concentration above the normal range, but below those which are diagnostic for diabetes. Subjects with IGT and/or IFG are at substantially higher risk of developing diabetes and cardiovascular disease than those with normal glucose tolerance. The benefits of clinical intervention in subjects with moderate glucose intolerance is a topic of much current interest.
Commonly, diabetic patients’ random blood glucose measurement will be greater than 200 mg/dL. Additionally, diabetic patients’ urinalysis will be positive for greater than 30 mg/g of microalbumin on at least two of three consecutive sampling dates. Type 2 diabetics who have had diabetes mellitus for more than 2 years will usually have a fasting C-peptide level greater than 1.0 ng/dL. Patients with type 1 diabetes will have islet cell and anti-insulin autoantibodies present in their blood within 6 months of diagnosis. These antibodies, though, usually fade after 6 months.
Type 2 DM is characterized by insulin resistance, which may be combined with relatively reduced insulin secretion.[11] The defective responsiveness of body tissues to insulin is believed to involve the insulin receptor. However, the specific defects are not known. Diabetes mellitus cases due to a known defect are classified separately. Type 2 DM is the most common type of diabetes mellitus.[2]
Diabetes mellitus is a disorder in which the amount of sugar in the blood is elevated. Doctors often use the full name diabetes mellitus, rather than diabetes alone, to distinguish this disorder from diabetes insipidus. Diabetes insipidus is a relatively rare disorder that does not affect blood glucose levels but, just like diabetes mellitus, also causes increased urination.
In this health topic, we discuss hyperglycemic hyperosmolar nonketotic syndrome (HHNS), an extremely serious complication that can lead to diabetic coma and even death in type 2 diabetes. This serious condition occurs when the blood sugar gets too high and the body becomes severely dehydrated. To prevent HHNS and diabetic coma in type 2 diabetes, check your blood sugar regularly as recommended by your health care provider; check your blood sugar more frequently when you are sick, drink plenty of fluids, and watch for signs of dehydration.
×