While there are competing explanations of the link between obesity and type 2 diabetes, Gerald Shulman, MD, PhD, a professor of internal medicine and physiology at Yale University, believes the key is figuring out insulin resistance. He has studied the causes of insulin resistance for 25 years and thinks he may have the answer to the weight-diabetes link.
Diabetes is a condition in which the body cannot properly store and use fuel for energy. The body's main fuel is a form of sugar called glucose, which comes from food (after it has been broken down). Glucose enters the blood and is used by cells for energy. To use glucose, the body needs a hormone called insulin that's made by the pancreas. Insulin is important because it allows glucose to leave the blood and enter the body's cells.
The primary complications of diabetes due to damage in small blood vessels include damage to the eyes, kidneys, and nerves.[32] Damage to the eyes, known as diabetic retinopathy, is caused by damage to the blood vessels in the retina of the eye, and can result in gradual vision loss and eventual blindness.[32] Diabetes also increases the risk of having glaucoma, cataracts, and other eye problems. It is recommended that diabetics visit an eye doctor once a year.[33] Damage to the kidneys, known as diabetic nephropathy, can lead to tissue scarring, urine protein loss, and eventually chronic kidney disease, sometimes requiring dialysis or kidney transplantation.[32] Damage to the nerves of the body, known as diabetic neuropathy, is the most common complication of diabetes.[32] The symptoms can include numbness, tingling, pain, and altered pain sensation, which can lead to damage to the skin. Diabetes-related foot problems (such as diabetic foot ulcers) may occur, and can be difficult to treat, occasionally requiring amputation. Additionally, proximal diabetic neuropathy causes painful muscle atrophy and weakness.
Type 1 DM is caused by autoimmune destruction of the insulin-secreting beta cells of the pancreas. The loss of these cells results in nearly complete insulin deficiency; without exogenous insulin, type 1 DM is rapidly fatal. Type 2 DM results partly from a decreased sensitivity of muscle cells to insulin-mediated glucose uptake and partly from a relative decrease in pancreatic insulin secretion.

a complex disorder of carbohydrate, fat, and protein metabolism that is primarily a result of a deficiency or complete lack of insulin secretion by the beta cells of the pancreas or resistance to insulin. The disease is often familial but may be acquired, as in Cushing's syndrome, as a result of the administration of excessive glucocorticoid. The various forms of diabetes have been organized into categories developed by the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus of the American Diabetes Association. Type 1 diabetes mellitus in this classification scheme includes patients with diabetes caused by an autoimmune process, dependent on insulin to prevent ketosis. This group was previously called type I, insulin-dependent diabetes mellitus, juvenile-onset diabetes, brittle diabetes, or ketosis-prone diabetes. Patients with type 2 diabetes mellitus are those previously designated as having type II, non-insulin-dependent diabetes mellitus, maturity-onset diabetes, adult-onset diabetes, ketosis-resistant diabetes, or stable diabetes. Those with gestational diabetes mellitus are women in whom glucose intolerance develops during pregnancy. Other types of diabetes are associated with a pancreatic disease, hormonal changes, adverse effects of drugs, or genetic or other anomalies. A fourth subclass, the impaired glucose tolerance group, also called prediabetes, includes persons whose blood glucose levels are abnormal although not sufficiently above the normal range to be diagnosed as having diabetes. Approximately 95% of the 18 million diabetes patients in the United States are classified as type 2, and more than 70% of those patients are obese. About 1.3 million new cases of diabetes mellitus are diagnosed in the United States each year. Contributing factors to the development of diabetes are heredity; obesity; sedentary life-style; high-fat, low-fiber diets; hypertension; and aging. See also impaired glucose tolerance, potential abnormality of glucose tolerance, previous abnormality of glucose tolerance.
Some older people cannot control what they eat because someone else is cooking for them—at home or in a nursing home or other institution. When people with diabetes do not do their own cooking, the people who shop and prepare meals for them must also understand the diet that is needed. Older people and their caregivers usually benefit from meeting with a dietitian to develop a healthy, feasible eating plan.
Ketoacidosis, a condition due to starvation or uncontrolled diabetes, is common in Type I diabetes. Ketones are acid compounds that form in the blood when the body breaks down fats and proteins. Symptoms include abdominal pain, vomiting, rapid breathing, extreme lethargy, and drowsiness. Patients with ketoacidosis will also have a sweet breath odor. Left untreated, this condition can lead to coma and death.
Over time, a prolonged exposure to high blood sugar can damage the nerves throughout the body — a condition called diabetic neuropathy. Some people may not have any symptoms of the damage, while others may notice numbness, tingling, or pain in the extremities. “At the beginning, [diabetic neuropathy] usually starts in the feet and then it progresses upward,” says Dr. Ovalle. Although most common in people who have had type 2 diabetes for 25 years or more, it can occur in people who have prediabetes as well. In some studies, almost 50 percent of unexplained peripheral neuropathy [in the extremities], whether painful or otherwise, turns out to be caused by prediabetes or diabetes, says Dr. Einhorn.
On behalf of the millions of Americans who live with or are at risk for diabetes, we are committed to helping you understand this chronic disease. Help us set the record straight and educate the world about diabetes and its risk factors by sharing the common questions and answers below. If you're new to type 2 diabetes, join our Living With Type 2 Diabetes program to get more facts.

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.

Diabetes experts feel that these blood glucose monitoring devices give patients a significant amount of independence to manage their disease process; and they are a great tool for education as well. It is also important to remember that these devices can be used intermittently with fingerstick measurements. For example, a well-controlled patient with diabetes can rely on fingerstick glucose checks a few times a day and do well. If they become ill, if they decide to embark on a new exercise regimen, if they change their diet and so on, they can use the sensor to supplement their fingerstick regimen, providing more information on how they are responding to new lifestyle changes or stressors. This kind of system takes us one step closer to closing the loop, and to the development of an artificial pancreas that senses insulin requirements based on glucose levels and the body's needs and releases insulin accordingly - the ultimate goal.
Per the WHO, people with fasting glucose levels from 6.1 to 6.9 mmol/l (110 to 125 mg/dl) are considered to have impaired fasting glucose.[67] people with plasma glucose at or above 7.8 mmol/l (140 mg/dl), but not over 11.1 mmol/l (200 mg/dl), two hours after a 75 gram oral glucose load are considered to have impaired glucose tolerance. Of these two prediabetic states, the latter in particular is a major risk factor for progression to full-blown diabetes mellitus, as well as cardiovascular disease.[68] The American Diabetes Association (ADA) since 2003 uses a slightly different range for impaired fasting glucose of 5.6 to 6.9 mmol/l (100 to 125 mg/dl).[69]

Examples of simple or refined carbohydrates, on the other hand, exist in various forms — from the sucrose in the table sugar you use to bake cookies, to the various kinds of added sugar in packaged snacks, fruit drinks, soda, and cereal. Simple carbohydrates are natural components of many fresh foods, too, such as the lactose in milk and the fructose in fruits, and therefore, a healthy, well-balanced diet will always contain these types of sugars.
Many studies have shown that awareness about the diabetes and its complications is poor among the general population specially in the rural areas6,7. There is an urgent need to create awareness among the population regarding diabetes and about the serious consequences of this chronic disorder. Epidemiological data from India have shown the presence of a number of risk factors which can be easily identified by simple non-invasive risk scores8,9. The major risk factors are listed in Box 1.
Polyuria is defined as an increase in the frequency of urination. When you have abnormally high levels of sugar in your blood, your kidneys draw in water from your tissues to dilute that sugar, so that your body can get rid of it through the urine. The cells are also pumping water into the bloodstream to help flush out sugar, and the kidneys are unable to reabsorb this fluid during filtering, which results in excess urination.

Eating a balanced diet that is rich in fiber, non-starchy vegetables, lean protein, and healthy fat can help get you to your goal weight and reduce your waist size and body mass index (BMI). Reducing your intake of sweetened beverages (juices, sodas) is the easiest way to lose weight and reduce blood sugars. If you are someone who has high blood pressure and are salt sensitive, aim to reduce your intake of sodium; do not add salt to your food, read package labels for added sodium, and reduce your intake of fast food and take out. Don't go on a diet. Instead, adapt a healthier way of eating, one that you'll enjoy for a long time.
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]
It is a considerable challenge to obtain the goals of the intensively treated patients in the DCCT with the vast majority of people with diabetes given the more limited health care resources typically available in routine practice. If diabetes control can be improved without significant damage to quality of life, the economic, health, and quality of life savings associated with a reduction in complications in later life will be vast. Although some people who have had poorly controlled diabetes over many years do not develop complications, complications commonly arise after 15–20 years of diabetes and individuals in their 40s or even 30s may develop several complications in rapid succession. However, up until the early 1980s, patients had no way of monitoring their own blood glucose levels at home. Urine glucose monitoring only told them when their blood glucose had exceeded the renal threshold of approximately 10 mmol/L (i.e., was far too high), without being able to discriminate between the too high levels of 7–10 mmol/L or the hypoglycemic levels below 4 mmol/L. Clinics relied on random blood glucose testing and there were no measures of average blood glucose over a longer period. Since the 1980s there have been measures of glycosylated hemoglobin (GHb, HbA1, or HbA1c) which indicate average blood glucose over a six to eight week period and measures of glycosylated protein, fructosamine, which indicates average blood glucose over a two-week period. Blood-glucose meters for patients were first introduced in the early 1980s and the accuracy and convenience of the meters and the reagent strips they use has improved dramatically since early models. By the late 1990s blood-glucose monitoring is part of the daily routine for most people using insulin in developed countries. Blood-glucose monitoring is less often prescribed for tablet- and diet-alone-treated patients, financial reasons probably being allowed to outweigh the educational value of accurate feedback in improving control long term. The reduced risk of hypoglycemia and diabetic ketoacidosis in NIDDM patients not using insulin means that acute crises rarely arise in these patients though their risk of long-term complications is at least as great as in IDDM and might be expected to be reduced if feedback from blood-glucose monitoring were provided.
While poor vision is hardly uncommon—more than 60 percent of the American population wears glasses or contacts, after all—sudden changes in your vision, especially blurriness, need to be addressed by your doctor. Blurry vision is often a symptom of diabetes, as high blood sugar levels can cause swelling in the lenses of your eye, distorting your sight in the process. Fortunately, for many people, the effect is temporary and goes away when their blood sugar is being managed.
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.
A study by Dabelea et al found that in teenagers and young adults in whom diabetes mellitus had been diagnosed during childhood or adolescence, diabetes-related complications and comorbidities—including diabetic kidney disease, retinopathy, and peripheral neuropathy (but not arterial stiffness or hypertension)—were more prevalent in those with type 2 diabetes than in those with type 1 disease. [44]
Visual impairment and blindness are common sequelae of uncontrolled diabetes. The three most frequently occurring problems involving the eye are diabetic retinopathy, cataracts, and glaucoma. photocoagulation of destructive lesions of the retina with laser beams can be used to delay further progress of pathologic changes and thereby preserve sight in the affected eye.
Jump up ^ Pignone M, Alberts MJ, Colwell JA, Cushman M, Inzucchi SE, Mukherjee D, Rosenson RS, Williams CD, Wilson PW, Kirkman MS (June 2010). "Aspirin for primary prevention of cardiovascular events in people with diabetes: a position statement of the American Diabetes Association, a scientific statement of the American Heart Association, and an expert consensus document of the American College of Cardiology Foundation". Diabetes Care. 33 (6): 1395–402. doi:10.2337/dc10-0555. PMC 2875463. PMID 20508233.

a complex disorder of carbohydrate, fat, and protein metabolism that is primarily a result of a deficiency or complete lack of insulin secretion by the beta cells of the pancreas or resistance to insulin. The disease is often familial but may be acquired, as in Cushing's syndrome, as a result of the administration of excessive glucocorticoid. The various forms of diabetes have been organized into categories developed by the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus of the American Diabetes Association. Type 1 diabetes mellitus in this classification scheme includes patients with diabetes caused by an autoimmune process, dependent on insulin to prevent ketosis. This group was previously called type I, insulin-dependent diabetes mellitus, juvenile-onset diabetes, brittle diabetes, or ketosis-prone diabetes. Patients with type 2 diabetes mellitus are those previously designated as having type II, non-insulin-dependent diabetes mellitus, maturity-onset diabetes, adult-onset diabetes, ketosis-resistant diabetes, or stable diabetes. Those with gestational diabetes mellitus are women in whom glucose intolerance develops during pregnancy. Other types of diabetes are associated with a pancreatic disease, hormonal changes, adverse effects of drugs, or genetic or other anomalies. A fourth subclass, the impaired glucose tolerance group, also called prediabetes, includes persons whose blood glucose levels are abnormal although not sufficiently above the normal range to be diagnosed as having diabetes. Approximately 95% of the 18 million diabetes patients in the United States are classified as type 2, and more than 70% of those patients are obese. About 1.3 million new cases of diabetes mellitus are diagnosed in the United States each year. Contributing factors to the development of diabetes are heredity; obesity; sedentary life-style; high-fat, low-fiber diets; hypertension; and aging. See also impaired glucose tolerance, potential abnormality of glucose tolerance, previous abnormality of glucose tolerance.
Home blood glucose monitoring kits are available so patients with diabetes can monitor their own levels. A small needle or lancet is used to prick the finger and a drop of blood is collected and analyzed by a monitoring device. Some patients may test their blood glucose levels several times during a day and use this information to adjust their doses of insulin.
As of 2015, an estimated 415 million people had diabetes worldwide,[8] with type 2 DM making up about 90% of the cases.[16][17] This represents 8.3% of the adult population,[17] with equal rates in both women and men.[18] As of 2014, trends suggested the rate would continue to rise.[19] Diabetes at least doubles a person's risk of early death.[2] From 2012 to 2015, approximately 1.5 to 5.0 million deaths each year resulted from diabetes.[8][9] The global economic cost of diabetes in 2014 was estimated to be US$612 billion.[20] In the United States, diabetes cost $245 billion in 2012.[21]
Some people who have type 2 diabetes can achieve their target blood sugar levels with diet and exercise alone, but many also need diabetes medications or insulin therapy. The decision about which medications are best depends on many factors, including your blood sugar level and any other health problems you have. Your doctor might even combine drugs from different classes to help you control your blood sugar in several different ways.
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.
When diabetes occurs in women during pregnancy, it is called gestational diabetes. It usually is diagnosed between the 24th and 28th weeks of pregnancy. Like in type 1 and type 2 diabetes, blood sugar levels become too high. When women are pregnant, more glucose is needed to nourish the developing baby. The body needs more insulin, which is produced by the pancreas. In some women, the body does not produce enough insulin to meet this need, and blood sugar levels rise, resulting in gestational diabetes.
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