Diabetes is a disease in which the body is unable to produce or unable to properly use and store glucose, a form of sugar. Glucose backs up in the bloodstream, causing one's blood glucose (sometimes referred to as blood sugar) to rise too high.
There are two major types of diabetes. In type 1 (formerly called juvenile-onset or insulin-dependent) diabetes, the pancreas completely stops producing any insulin, a hormone that enables the body to use glucose found in foods for energy. People with type 1 diabetes must take daily insulin injections to survive. This form of diabetes usually develops in children or young adults but can occur at any age.
Type 2 (formerly called adult-onset or non-insulin-dependent) diabetes results when the body doesn't produce enough insulin and/or is unable to use insulin properly, a condition known as insulin resistance. This form of diabetes usually occurs in people who are over 40, overweight, and have a family history of diabetes, although today it is increasingly occurring in younger people, particularly adolescents.
According to federal statistics, an estimated 18.2 million children and adults in the United States-6.3 percent of the population-have diabetes. An estimated 13 million of these people have been diagnosed, and some 5.2 million are thought to have type 2 diabetes without knowing it. Most people with diabetes have type 2; an estimated 800,000 have type 1. Diabetes is the sixth-leading cause of death by disease in the United States. The condition and its complications cost an estimated $132 billion annually in the United States alone, in terms of healthcare costs and lost productivity.
Poorly managed diabetes can lead to a host of long-term complications, including heart attack, stroke, blindness, kidney failure, blood vessel disease that may require an amputation, nerve damage, and impotence in men. But a nationwide study completed over a 10-year period showed that if people keep their blood glucose level as close to normal as possible, they can reduce their risk of developing some of these complications by 50 percent or more.
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Your body changes much of the food you eat into glucose, a type of sugar, which is then carried by the bloodstream to be used to power the millions of cells in your body. The cells cannot use glucose for energy without the help of insulin, a hormone made by the pancreas that helps glucose enter them. Diabetes is a disease in which the body's insulin-producing system malfunctions. Glucose then builds up to excessive levels in the bloodstream.
In type 2 diabetes, which used to be called adult-onset or non-insulin-dependent diabetes, the body produces insulin but either does not produce enough to properly convert food into energy or is not able to use the insulin it does make. This form of diabetes usually occurs in people who are over 40, overweight, and have a family history of diabetes. (In type 1 diabetes, which used to be called juvenile-onset or insulin-dependent diabetes, the body completely stops producing insulin. People with Type I diabetes must take daily insulin injections to survive. This form of diabetes usually develops in children or young adults but can occur at any age.)
In some people with type 2 diabetes, the body fails to produce enough insulin to meet their needs, and glucose that can't get into the cells builds up in the bloodstream. In many others, the pancreas is actually producing more insulin than would normally be needed to convert the food they've eaten into energy; because their cells are resistant to the effects of insulin in the bloodstream, the cells don't become unlocked and allow in enough of the glucose in the blood.
Scientists don't know exactly what causes this insulin resistance, and many expect that there are several different defects in the process of unlocking cells that cause insulin resistance. Medications for type 2 diabetes focus on different parts of this insulin-cell interaction to help improve blood glucose control. Some medications stimulate the pancreas to produce more insulin. Others improve how the body uses insulin by working on insulin resistance. Physical activity also seems to lessen insulin resistance.
The interplay of genetic and other possible risk factors for type 2 diabetes is not well understood.
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Patients with type 2 diabetes are more likely than those with type 1 to know of a relative with diabetes and, therefore, to believe that diabetes runs in the family. To some extent, the appearance of "clustering" of type 2 diabetes in families arises because type 2 is so much more common than type 1 diabetes in the general population: It accounts for 90 to 95 percent of the estimated 18.2 million cases in the country today. Moreover, the occurrence of multiple cases in a family may reflect shared environmental risk factors, such as obesity and sedentary lifestyle.
Genetics does, however, play an important part in determining who develops type 2 diabetes. Studies show that if one parent has the disease, children have a 7 to 14 percent chance of developing it. If both parents have type 2 diabetes, this increases to a 45 percent chance. If an identical twin has type 2 diabetes, there's a 58 to 75 percent chance that the other twin will develop it, too. By contrast, a person with no diabetes in the family has an 11 percent chance of developing type 2 diabetes by age 70.
While type 2 diabetes may have a strong genetic basis in some patients, the development of the disease in most people is dependent upon the effects of such environmental and behavioral factors as obesity and a sedentary lifestyle or an underlying susceptibility that is poorly understood.
Susceptibility to certain complications of diabetes also seems to be linked to genetics. However, careful blood glucose control is still an important mitigating factor.
Those at highest risk of developing type 2 diabetes:
- are age 45 or older
- are overweight
- are physically inactive
- have previously been identified as having impaired fasting glucose (IFG), a higher-than-normal level of blood glucose after fasting
- have previously been identified as having impaired glucose tolerance (IGT), a measure of how the body has processed a glucose solution two hours after drinking it
- have a family history of diabetes
- are members of certain ethnic groups (including Asian-American, African-American, Hispanic American, and American Indian)
- have had gestational diabetes or have given birth to a child weighing more than 9 pounds
- have elevated blood pressure
- have an HDL cholesterol level (the "good" cholesterol) of 35 mg/dl or lower and/or a triglyceride level of 250 mg/dl or higher
- have polycystic ovary syndrome
- have a history of vascular disease
Last reviewed on 11/10/2008
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