Diabetes

Diabetes is a disease in which the body does not produce or properly use insulin（胰岛素）. Insulin is a hormone that is needed to convert sugar, starches（淀粉） and other food into energy needed for daily life. The cause of diabetes continues to be a mystery, although both genetics and environmental factors such as obesity and lack of exercise appear to play roles.

There are 20.8 million children and adults in the United States, or 7% of the population, who have diabetes. While an estimated 14.6 million have been diagnosed with diabetes, unfortunately, 6.2 million people (or nearly one-third) are unaware that they have the disease.

In order to determine whether or not a patient has pre-diabetes or diabetes, health care providers conduct a Fasting Plasma Glucose Test (FPG) or an Oral Glucose Tolerance Test (OGTT). Either test can be used to diagnose pre-diabetes or diabetes. The American Diabetes Association recommends the FPG because it is easier, faster, and less expensive to perform.

With the FPG test, a fasting blood glucose level between 100 and 125 mg/dl signals pre-diabetes. A person with a fasting blood glucose level of 126 mg/dl or higher has diabetes.

In the OGTT test, a person's blood glucose level is measured after a fast and two hours after drinking a glucose-rich beverage. If the two-hour blood glucose level is between 140 and 199 mg/dl, the person tested has pre-diabetes. If the two-hour blood glucose level is at 200 mg/dl or higher, the person tested has diabetes.

Major Types of Diabetes

 Type 1 diabetes 

Results from the body's failure to produce insulin, the hormone that "unlocks" the cells of the body, allowing glucose to enter and fuel them. It is estimated that 5-10% of Americans who are diagnosed with diabetes have type 1 diabetes.

Type 2 diabetes   

Results from insulin resistance (a condition in which the body fails to properly use insulin), combined with relative insulin deficiency. Most Americans who are diagnosed with diabetes have type 2 diabetes.

Gestational diabetes  

Gestational （怀孕）diabetes affects about 4% of all pregnant women - about 135,000 cases in the United States each year.

Pre-diabetes  

Pre-diabetes is a condition that occurs when a person's blood glucose levels are higher than normal but not high enough for a diagnosis of type 2 diabetes. There are 54 million Americans who have pre-diabetes, in addition to the 20.8 million with diabetes.

Diabetes Symptoms 

Diabetes often goes undiagnosed because many of its symptoms seem so harmless. Recent studies indicate that the early detection of diabetes symptoms and treatment can decrease the chance of developing the complications of diabetes.

Some diabetes symptoms include: Frequent urination（撒尿）, Excessive thirst, Extreme hunger, Unusual weight loss, Increased fatigue, Irritability( 兴奋性，易怒), Blurry（模糊的） vision.

Diabetes is more common in African Americans, Latinos, Native Americans, Asian Americans and Pacific Islanders.

Debates about diabetes:

Myth #1  You can catch diabetes from someone else.
No.  Although we don’t know exactly why some people develop diabetes, we know diabetes is not contagious.  It can’t be caught like a cold or flu.  There seems to be some genetic link in diabetes, particularly type 2 diabetes.  Lifestyle factors also play a part.

Myth #2  People with diabetes can't eat sweets or chocolate.
If eaten as part of a healthy meal plan, or combined with exercise, sweets and desserts（餐后甜点） can be eaten by people with diabetes.  They are no more “off limits” to people with diabetes, than they are to people without diabetes. 

Myth #3  Eating too much sugar causes diabetes. 
No.  Diabetes is caused by a combination of genetic and lifestyle factors.  However, being overweight does increase your risk for developing type 2 diabetes.  If you have a history of diabetes in your family, eating a healthy meal plan and regular exercise are recommended to manage your weight.

Myth #4  People with diabetes should eat special diabetic foods.
A healthy meal plan for people with diabetes is the same as that for everyone – low in fat (especially saturated and trans fat), moderate in salt and sugar, with meals based on whole grain foods, vegetables and fruit.  Diabetic and “dietetic” versions of sugar-containing foods offer no special benefit. They still raise blood glucose levels, are usually more expensive and can also have a laxative effect if they contain sugar alcohols.

Myth #5  If you have diabetes, you should only eat small amounts of starchy foods, such as bread, potatoes and pasta. 
Starchy foods are part of a healthy meal plan.  What is important is the portion size.  Whole grain breads, cereals（谷类食品）, pasta, rice and starchy vegetables like potatoes, yams（山药）, peas and corn can be included in your meals and snacks.  The key is portions.  For most people with diabetes, having 3-4 servings of carbohydrate-containing foods is about right.  Whole grain starchy foods are also a good source of fiber, which helps keep your gut（内脏） healthy.

Myth #6  People with diabetes are more likely to get colds and other illnesses. 
No.  You are no more likely to get a cold or another illness if you have diabetes.  However, people with diabetes are advised to get flu shots. This is because any infection interferes with your blood glucose management, putting you at risk of high blood glucose levels and, for those with type 1 diabetes, an increased risk of ketoacidosis（酮酸中毒）.

Myth #7  Insulin causes atherosclerosis（动脉硬化症）(hardening of the arteries) and high blood pressure.
No, insulin does not cause atherosclerosis.  In the laboratory, there is evidence that insulin can initiate some of the early processes associated with atherosclerosis.  Therefore, some physicians were fearful that insulin might aggravate（使恶化，加重） the development of high blood pressure and hardening of the arteries.  But it doesn’t.

Myth #8  Insulin causes weight gain, and because obesity is bad for you, insulin should not be taken. 
Both the UKPDS (United Kingdom Prospective Diabetes Study) and the DCCT (Diabetes Control & Complications Trial) have shown that the benefit of glucose management with insulin far outweighs (no pun intended) the risk of weight gain. 

Myth #9  Fruit is a healthy food.  Therefore, it is ok to eat as much of it as you wish. 
Fruit is a healthy food.  It contains fiber and lots of vitamins and minerals.  Because fruit contains carbohydrate, it needs to be included in your meal plan.  Talk to your dietitian（营养学家） about the amount, frequency and types of fruits you should eat.

Unlike some traits, diabetes does not seem to be inherited in a simple pattern. Yet clearly, some people are born more likely to get diabetes than others.

What leads to diabetes?

Type 1 and type 2 diabetes have different causes.  Yet two factors are important in both.  First, you must inherit a predisposition（易患病的体质） to the disease. Second, something in your environment must trigger diabetes.

Genes alone are not enough.  One proof of this is identical twins.  Identical twins have identical genes.  Yet when one twin has type 1 diabetes, the other gets the disease at most only half the time.  When one twin has type 2 diabetes, the other's risk is at most 3 in 4.

Type 1 diabetes

In most cases of type 1 diabetes, people need to inherit risk factors from both parents.  We think these factors must be more common in whites because whites have the highest rate of type 1 diabetes.  Because most people who are at risk do not get diabetes, researchers want to find out what the environmental triggers are.

One trigger might be related to cold weather.  Type 1 diabetes develops more often in winter than summer and is more common in places with cold climates.  Another trigger might be viruses.  Perhaps a virus that has only mild effects on most people triggers type 1 diabetes in others.

Early diet may also play a role.  Type 1 diabetes is less common in people who were breastfed and in those who first ate solid foods at later ages.

In many people, the development of type 1 diabetes seems to take many years.  In experiments that followed relatives of people with type 1 diabetes, researchers found that most of those who later got diabetes had certain autoantibodies（自身抗体） in their blood for years before.

Type 2 diabetes

Type 2 diabetes has a stronger genetic basis than type 1, yet it also depends more on environmental factors.  Sound confusing?  What happens is that a family history of type 2 diabetes is one of the strongest risk factors for getting the disease but it only seems to matter in people living a Western lifestyle.

Americans and Europeans eat too much fat and too little carbohydrate and fiber, and they get too little exercise.  Type 2 diabetes is common in people with these habits. 

The ethnic groups in the United States with the highest risk are African Americans, Mexican Americans, and Pima Indians. In contrast, people who live in areas that have not become Westernized tend not to get type 2 diabetes, no matter how high their genetic risk.

Obesity is a strong risk factor for type 2 diabetes.  Obesity is most risky for young people and for people who have been obese for a long time.

Gestational diabetes is more of a puzzle.  Women who get diabetes while they are pregnant are more likely to have a family history of diabetes, especially on their mothers' side.  But as in other forms of diabetes, nongenetic factors play a role.  Older mothers and overweight women are more likely to get gestational diabetes.

Type 1 diabetes: your child's risk

In general, if you are a man with type 1 diabetes, the odds（机率）of your child getting diabetes are 1 in 17.  If you are a woman with type 1 diabetes and your child was born before you were 25, your child's risk is 1 in 25; if your child was born after you turned 25, your child's risk is 1 in 100. Your child's risk is doubled if you developed diabetes before age 11.  If both you and your partner have type 1 diabetes, the risk is between 1 in 10 and 1 in 4. There is an exception to these numbers.  About 1 in every 7 people with type 1 diabetes has a condition called type 2 polyglandular（多腺的）autoimmune（自体免疫的） syndrome.

In addition to having diabetes, these people also have thyroid（甲状腺）disease and a poorly working adrenal（肾上腺）gland.  Some also have other immune system disorders. If you have this syndrome, your child's risk of getting the syndrome including type 1 diabetes is 1 in 2.

Researchers are learning how to predict a person's odds of getting diabetes.  For example, most whites with type 1 diabetes have genes called HLA-DR3 or HLA-DR4. If you and your child are white and share these genes, your child's risk is higher.  (Suspect genes in other ethnic groups are less well studied. The HLA-DR7 gene may put African Americans at risk, and the HLA-DR9 gene may put Japanese at risk.)

Other tests can also make your child's risk clearer.  A special test that tells how the body responds to glucose can tell which school-aged children are most at risk.

Another more expensive test can be done for children who have siblings with type 1 diabetes.  This test measures antibodies to insulin, to islet cells in the pancreas（胰腺）, or to an enzyme called glutamic acid decarboxylase（谷氨酸脱羧酶）High levels can indicate that a child has a higher risk of developing type 1 diabetes.

Type 2 diabetes: your child's risk

Type 2 diabetes runs in families.  In part, this tendency is due to children learning bad habits eating a poor diet, not exercising--from their parents.  But there is also a genetic basis. In general, if you have type 2 diabetes, the risk of your child getting diabetes is 1 in 7 if you were diagnosed before age 50 and 1 in 13 if you were diagnosed after age 50.

Some scientists believe that a child's risk is greater when the parent with type 2 diabetes is the mother.  If both you and your partner have type 2 diabetes, your child's risk is about 1 in 2.

People with certain rare types of type 2 diabetes have different risks.  If you have the rare form called maturity-onset diabetes（成年糖尿病） of the young (MODY), your child has almost a 1-in-2 chance of getting it, too.