DIABETES

Today, diabetes mellitus is one of the most serious health challenges facing the United States. The following statistics illustrate the magnitude of this disease among African Americans.

• 2.8 million African Americans have diabetes.¹
• On average, African Americans are twice as likely to have diabetes as white Americans of similar age.¹
• Approximately 13 percent of all African Americans have diabetes.¹
• African Americans with diabetes are more likely to develop diabetes complications and experience greater disability from the complications than white Americans with diabetes.
• Death rates for people with diabetes are 27 percent higher for African Americans compared with whites.

What is diabetes?
Diabetes mellitus is a group of diseases characterized by high levels of blood glucose. It results from defects in insulin secretion, insulin action, or both. Diabetes can be associated with serious complications and premature death, but people with diabetes can take measures to reduce the likelihood of such occurrences.

Most African Americans (about 90 percent to 95 percent) with diabetes have type 2 diabetes. This type of diabetes usually develops in adults and is caused by the body's resistance to the action of insulin and to impaired insulin secretion. It can be treated with diet, exercise, diabetes pills, and injected insulin. A small number of African Americans (about 5 percent to 10 percent) have type 1 diabetes, which usually develops before age 20 and is always treated with insulin.

Diabetes can be diagnosed by three methods:

1. A fasting plasma glucose test with a value of 126 milligrams/deciliter (mg/dL) or greater.
2. A nonfasting plasma glucose value of 200 mg/dL or greater in people with symptoms of diabetes.
3. An abnormal oral glucose tolerance test with a 2-hour glucose value of 200 mg/dL or greater.

How many African Americans have diabetes?
Figure 1 shows the prevalence for African American men and women based on the NHANES III survey conducted in 1988-94.³ The proportion of the African American population that has diabetes rises from less than 1 percent for those aged younger than 20 years to as high as 32 percent for women age 65-74 years. Overall, among those age 20 years or older, the rate is 11.8 percent for women and 8.5 percent for men.

About one-third of total diabetes cases are undiagnosed among African Americans. This is similar to the proportion for other racial/ethnic groups in the United States.³

National health surveys during the past 35 years show that the percentage of the African American population that has been diagnosed with diabetes is increasing dramatically.⁴ The surveys in 1976-80 and in 1988-94 measured fasting plasma glucose and thus allowed an assessment of the prevalence of undiagnosed diabetes as well as of previously diagnosed diabetes. In 1976-80, total diabetes prevalence in African Americans ages 40 to 74 years was 8.9 percent; in 1988-94, total prevalence had increased to 18.2 percent--a doubling of the rate in just 12 years.³

Prevalence in African Americans is much higher than in white Americans. Among those ages 40 to 74 years in the 1988-94 survey, the rate was 11.2 percent for whites, but was 18.2 percent for African Americans.

How does diabetes affect African American children?
African American children seem to have lower rates of type 1 diabetes than white American children. Researchers tend to agree that genetics probably makes type 1 diabetes less common among children with African ancestry compared with children of European ancestry. However, recent reports indicate an increasing prevalance of type 2 diabetes in children, especially in those with African American, American Indian, or Hispanic family background.¹⁰

How does diabetes affect African American women during pregnancy?
Gestational diabetes, in which blood glucose values are elevated above normal during pregnancy, occurs in about 2 percent to 5 percent of all pregnant women. Perinatal problems such as macrosomia (large body size) and neonatal hypoglycemia (low blood sugar) are higher in these pregnancies. The women generally return to normal glucose values after childbirth. However, once a woman has had gestational diabetes, she has an increased risk of developing gestational diabetes in future pregnancies. In addition, experts estimate that about half of women with gestational diabetes develop type 2 diabetes within 20 years of the pregnancy.

Several studies have shown that the occurrence of gestational diabetes in African American women may be 50 percent to 80 percent more frequent than in white women.

How do diabetes complications affect African Americans?
Compared with white Americans, African Americans experience higher rates of diabetes complications such as eye disease, kidney failure, and amputations. They also experience greater disability from these complications. Some factors that influence the frequency of these complications, such as high blood glucose levels, abnormal blood lipids, high blood pressure, and cigarette smoking, can be influenced by proper diabetes management.

Eye Disease
Diabetic retinopathy is a deterioration of the blood vessels in the eye that is caused by high blood glucose. It can lead to impaired vision and, ultimately, to blindness. The frequency of diabetic retinopathy is 40 percent to 50 percent higher in African Americans than in white Americans, according to NHANES III data.¹¹ Retinopathy may also occur more frequently in African Americans than in whites because of their higher rate of hypertension. Although blindness caused by diabetic retinopathy is believed to be more frequent in African Americans than in whites, there are no valid studies that compare rates of blindness between the two groups.

Kidney Failure
African Americans with diabetes experience kidney failure, also called end-stage renal disease (ESRD), about four times more often than diabetic white Americans.¹² In 1995, there were 27,258 new cases of ESRD attributed to diabetes in African Americans.¹³ Diabetes is the leading cause of kidney failure and accounted for 43 percent of the new cases of ESRD among African Americans during 1992-1996. Hypertension, the second leading cause of ESRD, accounted for 42 percent of cases. In spite of their high rates of ESRD, African Americans have better survival rates after they develop kidney failure than white Americans.¹²

Amputations
Based on the U.S. hospital discharge survey, there were about 13,000 amputations among African American diabetic individuals in 1994, which involved 155,000 days in the hospital.¹⁴ African Americans with diabetes are much more likely to undergo a lower-extremity amputation than white or Hispanic Americans with diabetes. The hospitalization rate of amputations for African Americans was 9.3 per 1,000 patients in 1994, compared with 5.8 per 1,000 white diabetic patients. However, the average length of hospital stay was lower for African Americans (12.1 days) than for white Americans (16.5 days).

Does diabetes cause excess deaths in African Americans?
Diabetes was an uncommon cause of death among African Americans at the turn of the century. By 1994, however, death certificates listed diabetes as the seventh leading cause of death for African Americans. For those age 45 years or older, it was the fifth leading cause of death.¹⁴

Death rates (mortality) for people with diabetes are higher for African Americans than for whites. Figure 3 shows death rates for whites and African Americans with diabetes in a national survey of people first studied in 1971-1975 whose mortality was confirmed through 1992-1993.¹⁵ The overall mortality rate was 20 percent higher for African American men and 40 percent higher for African American women, compared with their white counterparts.