Type 2 diabetes is due to insufficient insulin production from beta cells in the setting of insulin resistance.[13] Insulin resistance, which is the inability of cells to respond adequately to normal levels of insulin, occurs primarily within the muscles, liver, and fat tissue.[44] In the liver, insulin normally suppresses glucose release. However, in the setting of insulin resistance, the liver inappropriately releases glucose into the blood.[10] The proportion of insulin resistance versus beta cell dysfunction differs among individuals, with some having primarily insulin resistance and only a minor defect in insulin secretion and others with slight insulin resistance and primarily a lack of insulin secretion.[13]
Type 2 diabetes is different. A person with type 2 diabetes still produces insulin but the body doesn't respond to it normally. Glucose is less able to enter the cells and do its job of supplying energy (a problem called insulin resistance). This raises the blood sugar level, so the pancreas works hard to make even more insulin. Eventually, this strain can make the pancreas unable to produce enough insulin to keep blood sugar levels normal.
Although some people with this type of diabetes are thin, the majority of people (90%) are overweight. Losing weight, even 2 kg to 5 kg (5 lbs to 10 lbs) can help lower blood glucose levels. For many people, following a healthy diet and an exercise program may be all that is needed to help control glucose levels. For others, healthy eating and exercise alone aren't enough to lower blood glucose levels.
Type 2 diabetes (formerly named non-insulin-dependent) which results from the body's inability to respond properly to the action of insulin produced by the pancreas. Type 2 diabetes is much more common and accounts for around 90% of all diabetes cases worldwide. It occurs most frequently in adults, but is being noted increasingly in adolescents as well.
Diabetes mellitus (DM), commonly referred to as diabetes, is a group of metabolic disorders in which there are high blood sugar levels over a prolonged period.[10] Symptoms of high blood sugar include frequent urination, increased thirst, and increased hunger.[2] If left untreated, diabetes can cause many complications.[2] Acute complications can include diabetic ketoacidosis, hyperosmolar hyperglycemic state, or death.[3] Serious long-term complications include cardiovascular disease, stroke, chronic kidney disease, foot ulcers, and damage to the eyes.[2]
People with diabetes either don't make insulin or their body's cells no longer are able to use the insulin, leading to high blood sugars. By definition, diabetes is having a blood glucose level of greater than or equal to126 milligrams per deciliter (mg/dL) after an 8-hour fast (not eating anything), or by having a non-fasting glucose level greater than or equal to 200 mg/dL along with symptoms of diabetes, or a glucose level of greater than or equal to 200 mg/dL on a 2-hour glucose tolerance test, or an A1C greater than or equal to 6.5%. Unless the person is having obvious symptoms of diabetes or is in a diabetic crisis, the diagnosis must be confirmed with a repeat test.
While it's conceivable that scientists will isolate a single factor as causing type 1 and type 2, the much more likely outcome is that there is more than one cause. Each person seems to take a unique path in developing diabetes. Someday, doctors may be able to assess an individual's genetic risk for diabetes, allowing him or her to dodge the particular environmental factors that would trigger the disease. And perhaps if the baffling question of why a person gets diabetes can be put to rest, the answer will also offer a cure for the disease.
Elevated homocysteine levels in the blood called hyperhomocysteinemia, is a sign that the body isn't producing enough of the amino acid homocysteine. is a rare and serious condition that may be inherited (genetic). People with homocystinuria die at an early age. Symptoms of hyperhomocysteinemia include developmental delays, osteoporosis, blood clots, heart attack, heart disease, stroke, and visual abnormalities.
Jump up ^ Boussageon, R; Supper, I; Bejan-Angoulvant, T; Kellou, N; Cucherat, M; Boissel, JP; Kassai, B; Moreau, A; Gueyffier, F; Cornu, C (2012). Groop, Leif, ed. "Reappraisal of metformin efficacy in the treatment of type 2 diabetes: a meta-analysis of randomised controlled trials". PLOS Medicine. 9 (4): e1001204. doi:10.1371/journal.pmed.1001204. PMC 3323508. PMID 22509138.
Findings from the Diabetes Control and Complications Trial (DCCT) and the United Kingdom Prospective Diabetes Study (UKPDS) have clearly shown that aggressive and intensive control of elevated levels of blood sugar in patients with type 1 and type 2 diabetes decreases the complications of nephropathy, neuropathy, retinopathy, and may reduce the occurrence and severity of large blood vessel diseases. Aggressive control with intensive therapy means achieving fasting glucose levels between 70-120 mg/dl; glucose levels of less than 160 mg/dl after meals; and a near normal hemoglobin A1c levels (see below).
Jump up ^ Seida, Jennifer C.; Mitri, Joanna; Colmers, Isabelle N.; Majumdar, Sumit R.; Davidson, Mayer B.; Edwards, Alun L.; Hanley, David A.; Pittas, Anastassios G.; Tjosvold, Lisa; Johnson, Jeffrey A. (Oct 2014). "Effect of Vitamin D3 Supplementation on Improving Glucose Homeostasis and Preventing Diabetes: A Systematic Review and Meta-Analysis". The Journal of Clinical Endocrinology & Metabolism. 99 (10): 3551–60. doi:10.1210/jc.2014-2136. PMC 4483466. PMID 25062463.
Our bodies break down the foods we eat into glucose and other nutrients we need, which are then absorbed into the bloodstream from the gastrointestinal tract. The glucose level in the blood rises after a meal and triggers the pancreas to make the hormone insulin and release it into the bloodstream. But in people with diabetes, the body either can't make or can't respond to insulin properly.

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.


While there is a strong genetic component to developing this form of diabetes, there are other risk factors - the most significant of which is obesity. There is a direct relationship between the degree of obesity and the risk of developing type 2 diabetes, and this holds true in children as well as adults. It is estimated that the chance to develop diabetes doubles for every 20% increase over desirable body weight.
Diabetes mellitus results mainly from a deficiency or diminished effectiveness of insulin that is normally produced by the beta cells of the pancreas. It is characterised by high blood sugar, altered sugar and glucose metabolism and this affects blood vessels and causes several organ damage. Causes of diabetes can be classified according to the types of diabetes.
People with type 1 diabetes are unable to produce any insulin at all. People with type 2 diabetes still produce insulin, however, the cells in the muscles, liver and fat tissue are inefficient at absorbing the insulin and cannot regulate glucose well. As a result, the body tries to compensate by having the pancreas pump out more insulin. But the pancreas slowly loses the ability to produce enough insulin, and as a result, the cells don’t get the energy they need to function properly.
Learning about the disease and actively participating in the treatment is important, since complications are far less common and less severe in people who have well-managed blood sugar levels.[76][77] The goal of treatment is an HbA1C level of 6.5%, but should not be lower than that, and may be set higher.[78] Attention is also paid to other health problems that may accelerate the negative effects of diabetes. These include smoking, elevated cholesterol levels, obesity, high blood pressure, and lack of regular exercise.[78] Specialized footwear is widely used to reduce the risk of ulceration, or re-ulceration, in at-risk diabetic feet. Evidence for the efficacy of this remains equivocal, however.[79]
Clinistix and Diastix are paper strips or dipsticks that change color when dipped in urine. The test strip is compared to a chart that shows the amount of glucose in the urine based on the change in color. The level of glucose in the urine lags behind the level of glucose in the blood. Testing the urine with a test stick, paper strip, or tablet that changes color when sugar is present is not as accurate as blood testing, however it can give a fast and simple reading.
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.
Hyperglycemia (ie, random blood glucose concentration of more than 200 mg/dL or 11 mmol/L) results when insulin deficiency leads to uninhibited gluconeogenesis and prevents the use and storage of circulating glucose. The kidneys cannot reabsorb the excess glucose load, causing glycosuria, osmotic diuresis, thirst, and dehydration. Increased fat and protein breakdown leads to ketone production and weight loss. Without insulin, a child with type 1 diabetes mellitus wastes away and eventually dies due to DKA. The effects of insulin deficiency are shown in the image below.
Insulin, a hormone released from the pancreas (an organ behind the stomach that also produces digestive enzymes), controls the amount of glucose in the blood. Glucose in the bloodstream stimulates the pancreas to produce insulin. Insulin helps glucose to move from the blood into the cells. Once inside the cells, glucose is converted to energy, which is used immediately, or the glucose is stored as fat or glycogen until it is needed.

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.
In patients with type 2 diabetes, stress, infection, and medications (such as corticosteroids) can also lead to severely elevated blood sugar levels. Accompanied by dehydration, severe blood sugar elevation in patients with type 2 diabetes can lead to an increase in blood osmolality (hyperosmolar state). This condition can worsen and lead to coma (hyperosmolar coma). A hyperosmolar coma usually occurs in elderly patients with type 2 diabetes. Like diabetic ketoacidosis, a hyperosmolar coma is a medical emergency. Immediate treatment with intravenous fluid and insulin is important in reversing the hyperosmolar state. Unlike patients with type 1 diabetes, patients with type 2 diabetes do not generally develop ketoacidosis solely on the basis of their diabetes. Since in general, type 2 diabetes occurs in an older population, concomitant medical conditions are more likely to be present, and these patients may actually be sicker overall. The complication and death rates from hyperosmolar coma is thus higher than in diabetic ketoacidosis.
Management. There is no cure for diabetes; the goal of treatment is to maintain blood glucose and lipid levels within normal limits and to prevent complications. In general, good control is achieved when the following occur: fasting plasma glucose is within a specific range (set by health care providers and the individual), glycosylated hemoglobin tests show that blood sugar levels have stayed within normal limits from one testing period to the next, the patient's weight is normal, blood lipids remain within normal limits, and the patient has a sense of health and well-being.
In type 1 diabetes, other symptoms to watch for include unexplained weight loss, lethargy, drowsiness, and hunger. Symptoms sometimes occur after a viral illness. In some cases, a person may reach the point of diabetic ketoacidosis (DKA) before a type 1 diagnosis is made. DKA occurs when blood glucose is dangerously high and the body can't get nutrients into the cells because of the absence of insulin. The body then breaks down muscle and fat for energy, causing an accumulation of ketones in the blood and urine. Symptoms of DKA include a fruity odor on the breath; heavy, taxed breathing; and vomiting. If left untreated, DKA can result in stupor, unconsciousness, and even death.

Diet. In general, the diabetic diet is geared toward providing adequate nutrition with sufficient calories to maintain normal body weight; the intake of food is adjusted so that blood sugar and serum cholesterol levels are kept within acceptable limits. Overweight diabetic patients should limit caloric intake until target weight is achieved. In persons with type 2 diabetes this usually results in marked improvement and may eliminate the need for drugs such as oral hypoglycemic agents.
The signs and symptoms of diabetes are disregarded by many because of the chronic progression of the disease. People do not consider this as a serious problem because unlike many other diseases the consequences of hyperglycaemia are not manifested immediately. People are not aware that damage can start several years before symptoms become noticeable. This is unfortunate because recognition of early symptoms can help to get the disease under control immediately and to prevent vascular complications.

No single environmental trigger has been identified as causing diabetes mellitus, however both infectious agents and dietary factors are thought to be important. Various viruses have been implicated in the development of type I DM. They may act by initiating or modifying the autoimmune process. In particular, the rubella virus and coxsackie viruses have been closely studied. In particular, congenital rubella infection has shown direct relationships with the development of type 1 diabetes mellitus. This is presumably due to the virus (or antibodies against it) damaging the beta cells of the pancreas. Some research has looked at dietary factors that may be associated with type 1 diabetes. In particular, cow’s milk proteins (such as bovine serum albumin) which may have some similarities to pancreatic islet cell markers may be able to trigger the autoimmune process. Other chemicals including nitrosamines have been identified as causes of diabetes mellitus in animal models, but not in humans.


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.
Using insulin to get blood glucose levels to a healthy level is a good thing, not a bad one. For most people, type 2 diabetes is a progressive disease. When first diagnosed, many people with type 2 diabetes can keep their blood glucose at a healthy level with a combination of meal planning, physical activity, and taking oral medications. But over time, the body gradually produces less and less of its own insulin, and eventually oral medications may not be enough to keep blood glucose levels in a healthy range. 
Jump up ^ Haw, JS; Galaviz, KI; Straus, AN; Kowalski, AJ; Magee, MJ; Weber, MB; Wei, J; Narayan, KMV; Ali, MK (6 November 2017). "Long-term Sustainability of Diabetes Prevention Approaches: A Systematic Review and Meta-analysis of Randomized Clinical Trials". JAMA Internal Medicine. 177 (12): 1808–17. doi:10.1001/jamainternmed.2017.6040. PMID 29114778.
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

Type 1 diabetes occurs when your immune system, the body’s system for fighting infection, attacks and destroys the insulin-producing beta cells of the pancreas. Scientists think type 1 diabetes is caused by genes and environmental factors, such as viruses, that might trigger the disease. Studies such as TrialNet are working to pinpoint causes of type 1 diabetes and possible ways to prevent or slow the disease.

In patients with type 2 diabetes, stress, infection, and medications (such as corticosteroids) can also lead to severely elevated blood sugar levels. Accompanied by dehydration, severe blood sugar elevation in patients with type 2 diabetes can lead to an increase in blood osmolality (hyperosmolar state). This condition can worsen and lead to coma (hyperosmolar coma). A hyperosmolar coma usually occurs in elderly patients with type 2 diabetes. Like diabetic ketoacidosis, a hyperosmolar coma is a medical emergency. Immediate treatment with intravenous fluid and insulin is important in reversing the hyperosmolar state. Unlike patients with type 1 diabetes, patients with type 2 diabetes do not generally develop ketoacidosis solely on the basis of their diabetes. Since in general, type 2 diabetes occurs in an older population, concomitant medical conditions are more likely to be present, and these patients may actually be sicker overall. The complication and death rates from hyperosmolar coma is thus higher than in diabetic ketoacidosis.
The good news is that prevention plays an important role in warding off these complications. By maintaining tight control of your blood glucose—and getting it as close to normal as possible—you’ll help your body function in the way that it would if you did not have diabetes. Tight control helps you decrease the chances that your body will experience complications from elevated glucose levels.
One of the key factors in Joslin’s treatment of diabetes is tight blood glucose control, so be certain that your treatment helps get your blood glucose readings as close to normal as safely possible. Patients should discuss with their doctors what their target blood glucose range is. It is also important to determine what your goal is for A1C readings (a test that determines how well your diabetes is controlled over the past 2-3 months). By maintaining blood glucose in the desired range, you’ll likely avoid many of the complications some people with diabetes face.
Apart from severe DKA or hypoglycemia, type 1 diabetes mellitus has little immediate morbidity. The risk of complications relates to diabetic control. With good management, patients can expect to lead full, normal, and healthy lives. Nevertheless, the average life expectancy of a child diagnosed with type 1 diabetes mellitus has been variously suggested to be reduced by 13-19 years, compared with their nondiabetic peers. [34]
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.

Using insulin to get blood glucose levels to a healthy level is a good thing, not a bad one. For most people, type 2 diabetes is a progressive disease. When first diagnosed, many people with type 2 diabetes can keep their blood glucose at a healthy level with a combination of meal planning, physical activity, and taking oral medications. But over time, the body gradually produces less and less of its own insulin, and eventually oral medications may not be enough to keep blood glucose levels in a healthy range. 

Jump up ^ Rubino, F; Nathan, DM; Eckel, RH; Schauer, PR; Alberti, KG; Zimmet, PZ; Del Prato, S; Ji, L; Sadikot, SM; Herman, WH; Amiel, SA; Kaplan, LM; Taroncher-Oldenburg, G; Cummings, DE; Delegates of the 2nd Diabetes Surgery, Summit (June 2016). "Metabolic Surgery in the Treatment Algorithm for Type 2 Diabetes: A Joint Statement by International Diabetes Organizations". Diabetes Care. 39 (6): 861–77. doi:10.2337/dc16-0236. PMID 27222544.
Type 2 diabetes is different. A person with type 2 diabetes still produces insulin but the body doesn't respond to it normally. Glucose is less able to enter the cells and do its job of supplying energy (a problem called insulin resistance). This raises the blood sugar level, so the pancreas works hard to make even more insulin. Eventually, this strain can make the pancreas unable to produce enough insulin to keep blood sugar levels normal.
Diabetes is a disease in which your blood glucose, or blood sugar, levels are too high. Glucose comes from the foods you eat. Insulin is a hormone that helps the glucose get into your cells to give them energy. With type 1 diabetes, your body does not make insulin. With type 2 diabetes, the more common type, your body does not make or use insulin well. Without enough insulin, the glucose stays in your blood.
Diabetes mellitus (DM) is a strong predictor of cardiovascular morbidity and mortality and is associated with both micro- and macrovascular complications.1 Cardiovascular disease (CVD) causes up to 70% of all deaths in people with DM. The epidemic of DM will thus be followed by a burden of diabetes-related vascular diseases. The number of DM patients increases with aging of the population, in part because of the increasing prevalence of obesity and sedentary lifestyle. Although the mortality from coronary artery disease (CAD) in patients without DM has declined since the 1990s, the mortality in men with type 2 diabetes (T2DM) has not changed significantly.2 Moreover, DM is an independent risk factor for heart failure. Heart failure is closely related to diabetic cardiomyopathy: changes in the structure and function of the myocardium are not directly linked to CAD or hypertension. Diabetic cardiomyopathy is clinically characterized by an initial increase in left ventricular stiffness and subclinical diastolic dysfunction, gradually compromising left ventricular systolic function with loss of contractile function and progress into overt congestive heart failure. DM accounts for a significant percentage of patients with a diagnosis of heart failure in epidemiologic studies such as the Framingham Study and the UK Prospective Diabetes Study (UKPDS).2 A 1% increase in glycated hemoglobin (HbA1c) correlates to an increment of 8% in heart failure.3 The prevalence of heart failure in elderly diabetic patients is up to 30%.3
At present, the American Diabetes Association does not recommend general screening of the population for type 1 diabetes, though screening of high risk individuals, such as those with a first degree relative (sibling or parent) with type 1 diabetes should be encouraged. Type 1 diabetes tends to occur in young, lean individuals, usually before 30 years of age; however, older patients do present with this form of diabetes on occasion. This subgroup is referred to as latent autoimmune diabetes in adults (LADA). LADA is a slow, progressive form of type 1 diabetes. Of all the people with diabetes, only approximately 10% have type 1 diabetes and the remaining 90% have type 2 diabetes.
The food that people eat provides the body with glucose, which is used by the cells as a source of energy. If insulin isn't available or doesn't work correctly to move glucose from the blood into cells, glucose will stay in the blood. High blood glucose levels are toxic, and cells that don't get glucose are lacking the fuel they need to function properly.

Rosiglitazone, a thiazolidinedione, has not been found to improve long-term outcomes even though it improves blood sugar levels.[93] Additionally it is associated with increased rates of heart disease and death.[94] Angiotensin-converting enzyme inhibitors (ACEIs) prevent kidney disease and improve outcomes in those with diabetes.[95][96] The similar medications angiotensin receptor blockers (ARBs) do not.[96] A 2016 review recommended treating to a systolic blood pressure of 140 to 150 mmHg.[97]
Insulin is a hormone produced by the beta cells within the pancreas in response to the intake of food. The role of insulin is to lower blood sugar (glucose) levels by allowing cells in the muscle, liver and fat to take up sugar from the bloodstream that has been absorbed from food, and store it away as energy. In type 1 diabetes (previously called insulin-dependent diabetes mellitus), the insulin-producing cells are destroyed and the body is not able to produce insulin naturally. This means that sugar is not stored away but is constantly released from energy stores giving rise to high sugar levels in the blood. This in turn causes dehydration and thirst (because the high glucose ‘spills over’ into the urine and pulls water out of the body at the same time). To exacerbate the problem, because the body is not making insulin it ‘thinks’ that it is starving so does everything it can to release even more stores of energy into the bloodstream. So, if left untreated, patients become increasingly unwell, lose weight, and develop a condition called diabetic ketoacidosis, which is due to the excessive release of acidic energy stores and causes severe changes to how energy is used and stored in the body.

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 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.
There is no known preventive measure for type 1 diabetes.[2] Type 2 diabetes – which accounts for 85–90% of all cases – can often be prevented or delayed by maintaining a normal body weight, engaging in physical activity, and consuming a healthy diet.[2] Higher levels of physical activity (more than 90 minutes per day) reduce the risk of diabetes by 28%.[71] Dietary changes known to be effective in helping to prevent diabetes include maintaining a diet rich in whole grains and fiber, and choosing good fats, such as the polyunsaturated fats found in nuts, vegetable oils, and fish.[72] Limiting sugary beverages and eating less red meat and other sources of saturated fat can also help prevent diabetes.[72] Tobacco smoking is also associated with an increased risk of diabetes and its complications, so smoking cessation can be an important preventive measure as well.[73]
One of the most common ways people with type 2 diabetes attempt to lower their blood sugar is by drastically reducing their intake of carbs. The ADA agrees that carbohydrate counting is essential if you have diabetes, but extreme diets like the ketogenic diet, which reduces carb intake to as little as 5 percent of your daily calories, can be risky for some people with diabetes. (36)
^ Jump up to: a b Cheng, J; Zhang, W; Zhang, X; Han, F; Li, X; He, X; Li, Q; Chen, J (May 2014). "Effect of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers on all-cause mortality, cardiovascular deaths, and cardiovascular events in patients with diabetes mellitus: a meta-analysis". JAMA Internal Medicine. 174 (5): 773–85. doi:10.1001/jamainternmed.2014.348. PMID 24687000.
DKA usually follows increasing hyperglycemia and symptoms of osmotic diuresis. Users of insulin pumps, by virtue of absent reservoirs of subcutaneous insulin, may present with ketosis and more normal blood glucose levels. They are more likely to present with nausea, vomiting, and abdominal pain, symptoms similar to food poisoning. DKA may manifest as respiratory distress.
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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