Excess glucose in the blood can damage small blood vessels in the nerves causing a tingling sensation or pain in the fingers, toes and limbs. Nerves that lie outside of the central nervous system may also be damaged, which is referred to as peripheral neuropathy. If nerves of the gastrointestinal tract are affected, this may cause vomiting, constipation and diarrhea.

Normally, blood glucose levels are tightly controlled by insulin, a hormone produced by the pancreas. Insulin lowers the blood glucose level. When the blood glucose elevates (for example, after eating food), insulin is released from the pancreas to normalize the glucose level by promoting the uptake of glucose into body cells. In patients with diabetes, the absence of insufficient production of or lack of response to insulin causes hyperglycemia. Diabetes is a chronic medical condition, meaning that although it can be controlled, it lasts a lifetime.
The WHO estimates that diabetes mellitus resulted in 1.5 million deaths in 2012, making it the 8th leading cause of death.[9][101] However another 2.2 million deaths worldwide were attributable to high blood glucose and the increased risks of cardiovascular disease and other associated complications (e.g. kidney failure), which often lead to premature death and are often listed as the underlying cause on death certificates rather than diabetes.[101][104] For example, in 2014, the International Diabetes Federation (IDF) estimated that diabetes resulted in 4.9 million deaths worldwide,[19] using modeling to estimate the total number of deaths that could be directly or indirectly attributed to diabetes.[20]
Some patients with type 2 DM can control their disease with a calorically restricted diet (for instance 1600 to 1800 cal/day), regular aerobic exercise, and weight loss. Most patients, however, require the addition of some form of oral hypoglycemic drug or insulin. Oral agents to control DM include sulfonylurea drugs (such as glipizide), which increase pancreatic secretion of insulin; biguanides or thiazolidinediones (such as metformin or pioglitazone), which increase cellular sensitivity to insulin; or a-glucosidase inhibitors (such as acarbose), which decrease the absorption of carbohydrates from the gastrointestinal tract. Both types of diabetics also may be prescribed pramlintide (Symlin), a synthetic analog of human amylin, a hormone manufactured in the pancreatic beta cells. It enhances postprandial glucose control by slowing gastric emptying, decreasing postprandial glucagon concentrations, and regulating appetite and food intake; thus pramlintide is helpful for patients who do not achieve optimal glucose control with insulin and/or oral antidiabetic agents. When combinations of these agents fail to normalize blood glucose levels, insulin injections are added. Tight glucose control can reduce the patient’s risk of many of the complications of the disease. See: illustration

Treatment of high blood pressure and high cholesterol levels, which can contribute to circulation problems, can help prevent some of the complications of diabetes as well. A low dose of aspirin taken daily is recommended in people with risk factors for heart disease. All people with diabetes who are between 40 and 75 years are given a statin (a drug to decrease cholesterol levels) regardless of cholesterol levels. Younger people with an elevated risk of heart disease should also take a statin .


Maturity onset diabetes of the young (MODY) is a rare autosomal dominant inherited form of diabetes, due to one of several single-gene mutations causing defects in insulin production.[52] It is significantly less common than the three main types. The name of this disease refers to early hypotheses as to its nature. Being due to a defective gene, this disease varies in age at presentation and in severity according to the specific gene defect; thus there are at least 13 subtypes of MODY. People with MODY often can control it without using insulin.
The symptoms may relate to fluid loss and polyuria, but the course may also be insidious. Diabetic animals are more prone to infections. The long-term complications recognized in humans are much rarer in animals. The principles of treatment (weight loss, oral antidiabetics, subcutaneous insulin) and management of emergencies (e.g. ketoacidosis) are similar to those in humans.[123]

Janis McWilliams, RN, MSN, CDE, BC-ADM, responds: Yes, in type 1 diabetes in particular, the onset of symptoms like frequent urination and extreme thirst can be very sudden. In type 2 diabetes, the symptoms tend to come about more gradually, and sometimes there are no signs at all. People who have symptoms should contact their health care provider immediately for an accurate diagnosis. Keep in mind that these symptoms could signal other problems, too.
Weight fluctuations also fall under the umbrella of possible diabetes signs and symptoms. When you lose sugar through frequent urination, you also lose calories. At the same time, diabetes may keep the sugar from your food from reaching your cells — leading to constant hunger. The combined effect is potentially rapid weight loss, especially if you have type 1 diabetes.
Patients need to ensure that their blood glucose levels are kept as normal as possible so that delicate tissues in the body (especially blood vessels in the eyes, kidneys and peripheral nerves) are not damaged by high glucose levels over a long period of time. To achieve this, patients need to measure their glucose regularly and learn how to adjust their insulin doses in order to optimise their glucose levels (diabetes control). Good diabetes control helps to minimise the risk of long-term diabetes complications, as well as short-term symptoms (such as thirst).
The term brittle diabetes has been used to refer to people who have dramatic recurrent swings in blood glucose levels, often for no apparent reason. However, this term is no longer used. People with type 1 diabetes may have more frequent swings in blood glucose levels because insulin production is completely absent. Infection, delayed movement of food through the stomach, and other hormonal disorders may also contribute to blood glucose swings. In all people who have difficulty controlling blood glucose, doctors look for other disorders that might be causing the problem and also give people additional education on how to monitor diabetes and take their drugs.

A fingerstick glucose test is most often used to monitor blood glucose. Most blood glucose monitoring devices (glucose meters) use a drop of blood obtained by pricking the tip of the finger with a small lancet. The lancet holds a tiny needle that can be jabbed into the finger or placed in a spring-loaded device that easily and quickly pierces the skin. Most people find that the pricking causes only minimal discomfort. Then, a drop of blood is placed on a reagent strip. The strip contains chemicals that undergo changes depending on the glucose level. The glucose meter reads the changes in the test strip and reports the result on a digital display. Some devices allow the blood sample to be obtained from other sites, such as the palm, forearm, upper arm, thigh, or calf. Home glucose meters are smaller than a deck of cards.


Heart disease accounts for approximately 50% of all deaths among people with diabetes in industrialized countries. Risk factors for heart disease in people with diabetes include smoking, high blood pressure, high serum cholesterol and obesity. Diabetes negates the protection from heart disease which pre-menopausal women without diabetes experience. Recognition and management of these conditions may delay or prevent heart disease in people with diabetes.

Also striking are the differences in incidence between mainland Italy (8.4 cases per 100,000 population) and the Island of Sardinia (36.9 cases per 100,000 population). These variations strongly support the importance of environmental factors in the development of type 1 diabetes mellitus. Most countries report that incidence rates have at least doubled in the last 20 years. Incidence appears to increase with distance from the equator. [31]


Diabetes mellitus is a public health problem around the world. In 1980, 108 million adults worldwide had diabetes (4.7% of the global population). By 2014 this had risen to 422 million adults (8.5% of the global population). By 2040, the number is expected to be 642 million adults. In the UK, there is estimated to be between 3 and 4 million people with diabetes. Type 2 diabetes accounts for more than 90% of all patients with diabetes. 
Jump up ^ Imperatore, Giuseppina; Boyle, James P.; Thompson, Theodore J.; Case, Doug; Dabelea, Dana; Hamman, Richard F.; Lawrence, Jean M.; Liese, Angela D.; Liu, Lenna L. (December 2012). "Projections of Type 1 and Type 2 Diabetes Burden in the U.S. Population Aged <20 Years Through 2050". Diabetes Care. 35 (12): 2515–20. doi:10.2337/dc12-0669. ISSN 0149-5992. PMC 3507562. PMID 23173134. Archived from the original on 2016-08-14.
Diabetes mellitus is a condition in which the body does not produce enough of the hormone insulin, resulting in high levels of sugar in the bloodstream. There are many different types of diabetes; the most common are type 1 and type 2 diabetes, which are covered in this article. Gestational diabetes occurs during the second half of pregnancy and is covered in a separate article. Diabetes can also be caused by disease or damage to the pancreas, Cushing's syndrome, acromegaly and there are also some rare genetic forms.
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.
Because people with type 2 diabetes produce some insulin, ketoacidosis does not usually develop even when type 2 diabetes is untreated for a long time. Rarely, the blood glucose levels become extremely high (even exceeding 1,000 mg/dL). Such high levels often happen as the result of some superimposed stress, such as an infection or drug use. When the blood glucose levels get very high, people may develop severe dehydration, which may lead to mental confusion, drowsiness, and seizures, a condition called hyperosmolar hyperglycemic state. Currently, many people with type 2 diabetes are diagnosed by routine blood glucose testing before they develop such severely high blood glucose levels.

When your blood sugar is out of whack, you just don’t feel well, says Cypress, and might become more short-tempered. In fact, high blood sugar can mimic depression-like symptoms. “You feel very tired, you don’t feel like doing anything, you don’t want to go out, you just want to sleep,” Cypress says. She’ll see patients who think they need to be treated for depression, but then experience mood improvement after their blood sugar normalizes.
If the amount of insulin available is insufficient, or if cells respond poorly to the effects of insulin (insulin insensitivity or insulin resistance), or if the insulin itself is defective, then glucose will not be absorbed properly by the body cells that require it, and it will not be stored appropriately in the liver and muscles. The net effect is persistently high levels of blood glucose, poor protein synthesis, and other metabolic derangements, such as acidosis.[60]
Jump up ^ Farmer, AJ; Perera, R; Ward, A; Heneghan, C; Oke, J; Barnett, AH; Davidson, MB; Guerci, B; Coates, V; Schwedes, U; O'Malley, S (27 February 2012). "Meta-analysis of individual patient data in randomised trials of self monitoring of blood glucose in people with non-insulin treated type 2 diabetes". The BMJ. 344: e486. doi:10.1136/bmj.e486. PMID 22371867.
With such a surplus of food nowadays, it's easy to overindulge without physical activity, leading to weight gain and, for some people, eventual Type 2 diabetes. "It's a lack of exercise and still eating like you're 20 years old," says Susan M. De Abate, a nurse and certified diabetes educator and team coordinator of the diabetes education program at Sentara Virginia Beach General Hospital.
Type 2 diabetes which accounts for 85-95 per cent of all diabetes has a latent, asymptomatic period of sub-clinical stages which often remains undiagnosed for several years1. As a result, in many patients the vascular complications are already present at the time of diagnosis of diabetes, which is often detected by an opportunistic testing. Asian populations in general, particularly Asian Indians have a high risk of developing diabetes at a younger age when compared with the western populations5. Therefore, it is essential that efforts are made to diagnose diabetes early so that the long term sufferings by the patients and the societal burden can be considerably mitigated.
There are a range of different symptoms in people with diabetes. They may feel thirsty, pass a large amount of urine, wake up overnight to pass urine, lose weight and have blurred vision. Patients are vulnerable to infections such as thrush and may present with this. Particularly in type 2 diabetes, patients may not be aware of their diabetes for several years and a diagnosis may only be made when they seek treatment for diabetes-related complications such as foot, eye or kidney problems. Some patients may become severely ill and be taken into hospital with an infection and/or very high blood sugar levels.
When the glucose concentration in the blood remains high over time, the kidneys will reach a threshold of reabsorption, and glucose will be excreted in the urine (glycosuria).[62] This increases the osmotic pressure of the urine and inhibits reabsorption of water by the kidney, resulting in increased urine production (polyuria) and increased fluid loss. Lost blood volume will be replaced osmotically from water held in body cells and other body compartments, causing dehydration and increased thirst (polydipsia).[60]
Every cell in the human body needs energy in order to function. The body's primary energy source is glucose, a simple sugar resulting from the digestion of foods containing carbohydrates (sugars and starches). Glucose from the digested food circulates in the blood as a ready energy source for any cells that need it. Insulin is a hormone or chemical produced by cells in the pancreas, an organ located behind the stomach. Insulin bonds to a receptor site on the outside of cell and acts like a key to open a doorway into the cell through which glucose can enter. Some of the glucose can be converted to concentrated energy sources like glycogen or fatty acids and saved for later use. When there is not enough insulin produced or when the doorway no longer recognizes the insulin key, glucose stays in the blood rather entering the cells.
Monitoring your caloric intake may be helpful if you’re overweight, but everyone with type 2 diabetes should track how many carbs they’re taking in. That can be tricky because carbs are in many of the common foods you may already eat, but there are both good and bad sources of carbs. Fruits and vegetables, for example, are good sources, while pretzels and cookies are bad sources. (29)
“It’s not like you wake up one day and all of a sudden you’re thirsty, hungry, and [going to the bathroom] all the time,” says Melissa Joy Dobbins, RD, a certified diabetes educator in Illinois and a spokesperson for the American Association of Diabetes Educators. “It picks up gradually.” Indeed, “most people are unaware that they have diabetes in its early or even middle phases,” says Aaron Cypess, MD, assistant professor of medicine at Harvard Medical School and staff physician at Joslin Diabetes Center. Just because you’re not keyed in doesn’t mean you’re immune from problems associated with diabetes, he adds. The longer you go without controlling diabetes, the greater your risk for heart disease, kidney disease, amputation, blindness, and other serious complications. “We recommend that people with risk factors for diabetes, such as a family history or being overweight, get evaluated on a regular basis,” Dr. Cypess says. If you’ve been feeling off, talk to your doctor about getting a simple blood test that can diagnose the disease. And pay attention to these subtle signs and symptoms of diabetes.
Often people don't experience symptoms of diabetes until their blood sugars are very high. Symptoms of diabetes include: increased thirst, increased urination, increased hunger, extreme fatigues, numbness and tingling in the extremities (hands and feet), cuts and wounds that are slow to heal, and blurred vision. Some people also experience other less common symptoms including weight loss, dry itchy skin, increased yeast infections, erectile dysfunction, and acanthosis nigricans (thick, "velvety" patches found in the folds or creases of skin, such as the neck, that is indicative of insulin resistance).
The amount of glucose in the bloodstream is tightly regulated by insulin and other hormones. Insulin is always being released in small amounts by the pancreas. When the amount of glucose in the blood rises to a certain level, the pancreas will release more insulin to push more glucose into the cells. This causes the glucose levels in the blood (blood glucose levels) to drop.
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]
To explain what hemoglobin A1c is, think in simple terms. Sugar sticks, and when it's around for a long time, it's harder to get it off. In the body, sugar sticks too, particularly to proteins. The red blood cells that circulate in the body live for about three months before they die off. When sugar sticks to these hemoglobin proteins in these cells, it is known as glycosylated hemoglobin or hemoglobin A1c (HBA1c). Measurement of HBA1c gives us an idea of how much sugar is present in the bloodstream for the preceding three months. In most labs, the normal range is 4%-5.9 %. In poorly controlled diabetes, its 8.0% or above, and in well controlled patients it's less than 7.0% (optimal is <6.5%). The benefits of measuring A1c is that is gives a more reasonable and stable view of what's happening over the course of time (three months), and the value does not vary as much as finger stick blood sugar measurements. There is a direct correlation between A1c levels and average blood sugar levels as follows.
Type 2 diabetes usually begins with insulin resistance, a condition in which muscle, liver, and fat cells do not use insulin well. As a result, your body needs more insulin to help glucose enter cells. At first, the pancreas makes more insulin to keep up with the added demand. Over time, the pancreas can’t make enough insulin, and blood glucose levels rise.
Diabetes mellitus is a serious metabolic disease, affecting people of all geographic, ethnic or racial origin and its prevalence is increasing globally1. Burden from this costly disease is high on the low and middle income countries (LMIC) where the impacts of modernization and urbanization have caused marked adverse changes in lifestyle parameters.
Autonomic changes involving cardiovascular control (eg, heart rate, postural responses) have been described in as many as 40% of children with diabetes. Cardiovascular control changes become more likely with increasing duration and worsening control. [18] In a study by 253 patients with type 1 diabetes (mean age at baseline 14.4 y), Cho et al reported that the prevalence of cardiac autonomic dysfunction increases in association with higher body mass index and central adiposity. [19]

Large, population-based studies in China, Finland and USA have recently demonstrated the feasibility of preventing, or delaying, the onset of diabetes in overweight subjects with mild glucose intolerance (IGT). The studies suggest that even moderate reduction in weight and only half an hour of walking each day reduced the incidence of diabetes by more than one half.


Retinopathy: If blood sugar levels are too high, they can damage the eyes and cause vision loss and blindness. Retinopathy causes the development and leaking of new blood vessels behind the eye. Other effects of diabetes, such as high blood pressure and high cholesterol, can make this worse. According to the CDC, early treatment can prevent or reduce the risk of blindness in an estimated 90 percent of people with diabetes.

Apart from these medications, treating diabetes effectively means taking a well-rounded approach: You’ll need to eat well, exercise, and manage stress, because all these factors can affect your blood sugar levels. Staying healthy with diabetes also requires caring for yourself — like protecting your feet, practicing oral hygiene, and tending to your mental health.
When you have diabetes, excess sugar (glucose) builds up in your blood. Your kidneys are forced to work overtime to filter and absorb the excess sugar. If your kidneys can't keep up, the excess sugar is excreted into your urine, dragging along fluids from your tissues. This triggers more frequent urination, which may leave you dehydrated. As you drink more fluids to quench your thirst, you'll urinate even more.
Insulin inhibits glucogenesis and glycogenolysis, while stimulating glucose uptake. In nondiabetic individuals, insulin production by the pancreatic islet cells is suppressed when blood glucose levels fall below 83 mg/dL (4.6 mmol/L). If insulin is injected into a treated child with diabetes who has not eaten adequate amounts of carbohydrates, blood glucose levels progressively fall.
The information contained in this monograph is for educational purposes only. This information is not a substitute for professional medical advice, diagnosis, or treatment. If you have or suspect you may have a health concern, consult your professional health care provider. Reliance on any information provided in this monograph is solely at your own risk.
Morbidity and mortality stem from the metabolic derangements and from the long-term complications that affect small and large vessels, resulting in retinopathy, nephropathy, neuropathy, ischemic heart disease, and arterial obstruction with gangrene of extremities.2 The acute clinical manifestations can be fully understood in the context of current knowledge of the secretion and action of insulin.3 Genetic and other etiologic considerations implicate autoimmune mechanisms in the evolution of the most common form of childhood diabetes, known as type 1a diabetes.4,5 Genetic defects in insulin secretion are increasingly recognized and understood as defining the causes of monogenic forms of diabetes such as maturity-onset diabetes of youth (MODY) and neonatal DM and contributing to the spectrum of T2DM.6
Diabetes insipidus is characterized by excessive urination and thirst, as well as a general feeling of weakness. While these can also be symptoms of diabetes mellitus, if you have diabetes insipidus your blood sugar levels will be normal and no sugar present in your urine. Diabetes insipidus is a problem of fluid balance caused by a problem with the kidneys, where they can't stop the excretion of water. Polyuria (excessive urine) and polydipsia (excessive thirst) occur in diabetes mellitus as a reaction to high blood sugar.
The treatment of low blood sugar consists of administering a quickly absorbed glucose source. These include glucose containing drinks, such as orange juice, soft drinks (not sugar-free), or glucose tablets in doses of 15-20 grams at a time (for example, the equivalent of half a glass of juice). Even cake frosting applied inside the cheeks can work in a pinch if patient cooperation is difficult. If the individual becomes unconscious, glucagon can be given by intramuscular injection.
Diabetic ketoacidosis can be caused by infections, stress, or trauma, all of which may increase insulin requirements. In addition, missing doses of insulin is also an obvious risk factor for developing diabetic ketoacidosis. Urgent treatment of diabetic ketoacidosis involves the intravenous administration of fluid, electrolytes, and insulin, usually in a hospital intensive care unit. Dehydration can be very severe, and it is not unusual to need to replace 6-7 liters of fluid when a person presents in diabetic ketoacidosis. Antibiotics are given for infections. With treatment, abnormal blood sugar levels, ketone production, acidosis, and dehydration can be reversed rapidly, and patients can recover remarkably well.
Doctors can also measure the level of a protein, hemoglobin A1C (also called glycosylated or glycolated hemoglobin), in the blood. Hemoglobin is the red, oxygen-carrying substance in red blood cells. When blood is exposed to high blood glucose levels over a period of time, glucose attaches to the hemoglobin and forms glycosylated hemoglobin. The hemoglobin A1C level (reported as the percentage of hemoglobin that is A1C) reflects long-term trends in blood glucose levels rather than rapid changes.
“I don’t think that anybody has put their finger on what the true cause of diabetes is, or that we’re going to find a single cause,” Grieger says. So if you’ve been diagnosed with prediabetes or have other risk factors for the disease, avoiding any one food group entirely — even sugar — won’t completely offset your risk. Rather, it’s important to prioritize proper nutrition, exercise regularly, and maintain a healthy weight — all steps the American Diabetes Association recommends for preventing type 2 diabetes.
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
Sugar doesn't cause diabetes. But there is one way that sugar can influence whether a person gets type 2 diabetes. Consuming too much sugar (or sugary foods and drinks) can make people put on weight. Gaining too much weight leads to type 2 diabetes in some people. Of course, eating too much sugar isn't the only cause of weight gain. Weight gain from eating too much of any food can make a person's chance of getting diabetes greater.
American Diabetes Association Joslin Diabetes Center Mayo Clinic International Diabetes Federation Canadian Diabetes Association National Institute of Diabetes and Digestive and Kidney Diseases Diabetes Daily American Heart Association Diabetes Forecast Diabetic Living American Association of Clinical Endocrinologists European Association for the Study of Diabetes
The classic presenting symptoms of type 1 diabetes mellitus are discussed below. For some children, the first symptoms of diabetes mellitus are those of diabetic ketoacidosis. This is a serious and life-threatening condition, requiring immediate treatment. Ketoacidosis occurs due to a severe disturbance in the body’s metabolism. Without insulin, glucose cannot be taken up into cells. Instead fats are broken down for energy which can have acid by-products.  
Type 1 diabetes mellitus has wide geographic variation in incidence and prevalence. [30] Annual incidence varies from 0.61 cases per 100,000 population in China to 41.4 cases per 100,000 population in Finland. Substantial variations are observed between nearby countries with differing lifestyles, such as Estonia and Finland, and between genetically similar populations, such as those in Iceland and Norway.
In the United States alone, more than 8 million people have undiagnosed diabetes, according to the American Diabetes Association. But you don't need to become a statistic. Understanding possible diabetes symptoms can lead to early diagnosis and treatment — and a lifetime of better health. If you're experiencing any of the following diabetes signs and symptoms, see your doctor.
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."
×