One-third of adults with diabetes still don't know they have it

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Public release date: 26-May-2006

One-third of adults with diabetes still don't know they have it

The prevalence of diagnosed diabetes in U.S. adults age 20 and older

has risen from about 5.1 percent to 6.5 percent, according to

researchers at the National Institutes of Health (NIH) and the

Centers for Disease Control and Prevention (CDC), who analyzed

national survey data from two periods--1988 to 1994 and 1999 to 2002.

However, the percentage of adults with undiagnosed diabetes did not

change significantly over the years studied. About 2.8 percent of

U.S. adult--one-third of those with diabete--still don't know they

have it. The study, published in the June 2006 issue of Diabetes

Care, notes that type 2 diabetes accounts for up to 95 percent of all

diabetes cases and virtually all undiagnosed diabetes cases. Diabetes

is a group of diseases marked by high levels of blood glucose

resulting from defects in insulin production, insulin action, or

both. It is the most common cause of blindness, kidney failure, and

amputations in adults and a major cause of heart disease and stroke.

Over the years studied, about 26 percent of adults age 20 and older

continued to have impaired fasting glucose (IFG), a form of pre-

diabetes. IFG, in which blood glucose measured after an overnight

fast is high but not yet diagnostic of diabetes, increases the risk

of heart disease as well as the risk of developing type 2 diabetes.

" It's important to know if you have pre-diabetes or undiagnosed type

2 diabetes, " said Dr. Larry Blonde, chair of the National Diabetes

Education Program (NDEP), jointly sponsored by the NIH, CDC, and 200

partner organizations. " You should talk to your health care

professional about your risk. If your blood glucose is high but not

high enough to be diagnosed as diabetes, losing weight and increasing

physical activity will greatly lower your risk of getting type 2

diabetes. If you have diabetes, controlling your blood glucose, blood

pressure, and cholesterol will prevent or delay the complications of

diabetes. "

The researchers also found that:

nearly 22 percent of people age 65 and older had diabetes.

about 13 percent of non-Hispanic blacks age 20 and older had

diabetes. Diabetes was twice as common in non-Hispanic blacks

compared to non-Hispanic whites.

about 8 percent of Mexican Americans age 20 and older had diabetes.

Because the average age of Mexican Americans is younger than for

other groups, the age-and sex-adjusted prevalence of diabetes in

Mexican Americans is twice that of non-Hispanic whites and about

equal to that of non-Hispanic blacks.

IFG and undiagnosed diabetes were about 70 percent more common in men

than in women, especially in non-Hispanic white men.

nearly 40 percent of people age 65 and older had IFG, which becomes

more common with age.

In the study, the researchers compared two slices of data, one from

1988 to 1994 and the other from 1999 to 2002. The data were derived

from a national sample of U.S. adults age 20 years and older who took

part in the National Health and Nutrition Examination Survey (NHANES)

conducted by the CDC's National Center for Health Statistics. Survey

participants were interviewed in their homes and received a physical

exam with a blood test, which included a glucose reading taken after

an overnight fast. The NHANES is unique because it includes a blood

test that detects undiagnosed diabetes and IFG.

" This study updates and generally corroborates earlier analyses that

were based on 2 years of NHANES data, " said lead author

Cowie, Ph.D., of the National Institute of Diabetes and Digestive and

Kidney Diseases (NIDDK). " We're seeing a rising prevalence of

diagnosed diabetes that is not substantially offset by a drop in the

rate of undiagnosed--about one-third of adults with diabetes still

don't know they have it. Another 26 percent of adults have a form of

pre-diabetes. "

Pre-diabetes, which usually causes no symptoms, is serious because

many people with the condition develop type 2 diabetes in the next 10

years. Also, pre-diabetes substantially raises the risk of a heart

attack or stroke even if type 2 diabetes does not develop.

People with pre-diabetes may have IFG or impaired glucose tolerance

(IGT) or both.

In IFG, blood glucose is high (100 to 125 milligrams per deciliter or

mg/dL) after an overnight fast but not high enough to be diagnostic

of diabetes.

In IGT, blood glucose is high (140 to 199 mg/dL) 2 hours after

drinking a sugary drink in an oral glucose tolerance test but not

high enough to be diagnostic of diabetes.

In the current study, researchers did not assess the prevalence of

IGT because an oral glucose tolerance test was not a part of the survey.

People with pre-diabetes can often prevent or delay diabetes if they

lose a modest amount of weight by cutting calories in their diet and

increasing physical activity (for example, walking 30 minutes a day 5

days a week). A major study of people with IGT has shown that

lifestyle changes leading to a 5 to 7 percent weight loss lowered

diabetes onset by 58 percent.

If you are over age 45, you should consult your health care provider

about testing for pre-diabetes or diabetes. If you are younger than

45, overweight, and have another risk factor, you should ask about

testing. You are at greater risk of developing pre-diabetes and type

2 diabetes if you:

are age 45 or older

have a family history of diabetes

are overweight

have an inactive lifestyle (exercise less than three times a week)

are members of a high-risk ethnic population (e.g., African American,

Hispanic/Latino American, American Indian and Alaska Native, Asian

American, Pacific Islander)

have high blood pressure: 140/90 mm/Hg or higher

have an HDL cholesterol less than 35 mg/dL or a triglyceride level

250 mg/dL or higher

have had diabetes that developed during pregnancy (gestational

diabetes) or have given birth to a baby weighing more than 9 pounds

have polycystic ovary syndrome, a metabolic disorder that affects the

female reproductive system

have acanthosis nigricans (dark, thickened skin around neck or armpits)

have a history of disease of the blood vessels to the heart, brain,

or legs

have had IFG or IGT on previous testing.

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In its " Small Steps. Big Rewards. Prevent Type 2 Diabetes " campaign,

the NDEP (www.ndep.nih.gov/) is reaching out to people at risk for

type 2 diabetes with the message that they have the power to turn the

tide against this disease. The NDEP campaign, " Control Your Diabetes

for Life, " encourages people with diabetes to control their blood

glucose as well as their blood pressure and cholesterol. By keeping

all three as close to normal as possible, people with diabetes can

prevent or delay the development and progression of diabetes

complications, which affect the heart, eyes, nerves, kidneys, and

blood vessels.

For more diabetes statistics, see http://diabetes.niddk.nih.gov/dm/

pubs/statistics/index.htm

The NIH and the CDC are agencies of the U.S. Department of Health and

Human Services. The NIH, which includes 27 Institutes and Centers, is

the primary Federal agency for conducting and supporting basic,

clinical, and translational medical research, and investigates the

causes, treatments, and cures for both common and rare diseases. For

more information about NIH and its programs, see www.nih.gov. For

information about CDC and its programs, see www.cdc.gov.

http://www.eurekalert.org/pub_releases/2006-05/niod-ooa052306.php