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Diabetes in American Indians and Alaska Natives

Diabetes mellitus is one of the most serious health challenges facing American Indians and Alaska Natives in the United States today. The disease is very common in many tribes, and morbidity and mortality from diabetes can be severe.

This population includes all people who derive their origins from any of the original peoples of North America and who continue to maintain cultural identification through tribal affiliations or community recognition. Great diversity in culture, language, location, lifestyles, and genetic heritage exists among American Indians and Alaska Natives. More than 500 Native American tribal organizations, with many differences in language and culture, exist in the United States.

In 1990, the U.S. Census Bureau used self-identification to classify people as part of this group. The American Indian and Alaska Native population was estimated at about 2 million.1 [11] Between the 1980 Census and the 1990 Census, a 38 percent increase occurred in the number of people who identified themselves as American Indians or Alaska Natives. This increase reflects an actual rise in the number of people who identify themselves as part of this group, as well as improvements in counting methodology. In 1990, more than half of the American Indian and Alaska Native population lived in the following seven States: Alaska, Arizona, California, New Mexico, North Carolina, Oklahoma, and Washington. The 1990 Census in Alaska showed a total of 85,698 self-identified Alaska Natives. Alaska Natives include three main population groups: Eskimo, Indian, and Aleut.2 [12] Within these three groups are further divisions based on geographic location, and linguistic and cultural differences.

Within the estimated 2 million self-identified American Indians, about 1.2 million live on 33 reservations served by the Indian Health Service (IHS).1 [11] Increasingly, tribal organizations are contracting directly with the Federal Government to operate health care facilities on reservations. The following data on American Indians are drawn primarily from information about American Indians living on reservations, not from American Indians living outside of the reservations.

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What Is Diabetes?

Diabetes mellitus is a group of diseases characterized by high blood levels of glucose. It results from defects in insulin secretion, in 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 disability and death.

Most American Indians and Alaska Natives with diabetes have type 2 diabetes, which usually develops in adults but can develop in children or adolescents. Type 2 diabetes is caused by the body's resistance to the action of insulin and by impaired insulin secretion. It can be managed with healthy eating, physical activity, oral diabetes medications, and/or injected insulin. Until recently, type 2 diabetes was rarely diagnosed in children and adolescents. However, type 2 diabetes is now common in American Indian children age 10 and older.3 [13] A small number of American Indians (about 2 to 4 percent) have type 1 diabetes, which usually develops before age 20 and is managed with insulin, healthy eating, and physical activity.

Diabetes can be diagnosed by three methods4 [14]:

Each test must be confirmed, on another day, by any of the above methods.


How Many American Indians and Alaska Natives Have Diabetes?

Type 2 Diabetes

About 9 percent of American Indians and Alaska Natives have been diagnosed with diabetes. On average, they are 2.8 times as likely to have diagnosed diabetes as non-Hispanic whites of a similar age.5 [15] The available data probably underestimate the true prevalence of diabetes in this population. For example, 40 to 70 percent of American Indian adults age 45 to 74 were found to have diabetes in a recent screening study in three geographic areas.6 [16] Data from the Navajo Health and Nutrition Survey, published in 1997, showed that 22.9 percent of Navajo adults age 20 and older had diabetes. Fourteen percent had a history of diabetes, but another 7 percent were found to have undiagnosed diabetes during the survey.7 [17]

Type 2 diabetes is becoming increasingly common in youth. Researchers studying 5,274 Pima Indian children from 1967 to 1996 found that the prevalence of type 2 diabetes in girls age 10 to 14 increased from 0.72 percent in the period 1967 to 1976 to 2.88 percent in the period 1987 to 1996.3 [13] Current reports include an increasing incidence in First Nation populations in Canada.8 [18]

Of the 2.3 million self-identified American Indians/Alaska Natives who receive care from the IHS, about 70,000 had diabetes in 1998.9 [19] Diabetes rates for American Indians vary by tribal group, as shown in table 1.

Diabetes is particularly common among middle-age and older American Indians and Alaska Natives. Its prevalence in American Indians and Alaska Natives, compared with that of non-Hispanic whites by age group and sex, is shown in table 2.

TABLE 1.

Age-adjusted prevalence of diagnosed diabetes among American Indians/Alaska Natives, age 20 and older, by group of tribes--United States, 1997.

Group
of Tribes

Geographic Area
Prevalence (%)
Alaska
Alaska
4.4
Atlantic
Alabama, Connecticut, Florida, Louisiana, Maine, Mississippi, New York, North Carolina, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas
21.0
Great Lakes
Michigan, Minnesota, Wisconsin
15.2
Northern Plains
Iowa, Montana, Nebraska, North Dakota, South Dakota, Wyoming
16.3
Pacific Tribes
California, Idaho, Oregon, Washington
7.0
Southern Plains
Kansas, Oklahoma
9.6
Southwest
Arizona, Colorado, Nevada, New Mexico, Utah
13.9

Note: Age-adjusted to the 1980 U.S. population; prevalance is per 100 persons.

Data on American Indians/Alaska Natives are from the 1997 Indian Health Service (IHS) Patient Care Component file; excludes data from 27 (representing 12 percent of the population served by IHS) of the 145 IHS service units that report data to the IHS because the data were incomplete.

Source: R�os Burrows (1999, July 26).10 [20]

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TABLE 2.

Prevalence of diagnosed diabetes among American Indians/Alaska Natives and non-Hispanic whites, age 20 and older, by age and sex--United States, 1997.


Men
Men
Women
Women
All
All
Age Group (Years)
American Indians/ Alaska Natives
Non- Hispanic Whites
American Indians/ Alaska Natives
Non- Hispanic Whites
American Indians/ Alaska Natives
Non- Hispanic Whites
20-44
3.2
0.6
4.1
1.3
3.7
0.9
45-64
17.8
5.4
21.7
5.1
19.9
5.2
65 and older
19.8
11.8
24.6
11.2
22.6
11.4
20 and older
8.1
3.9
10.6
4.5
9.4
4.2
Age Adjusted prevalence
10.2
3.8
12.6
4.0
11.5
3.9

Note: Prevalance was per 100 persons; age-adjusted data are age-adjusted to 1980 U.S. population.

Data on American Indians/Alaska Natives are from the 1997 Indian Health Service (IHS) Patient Care Component file; excludes data from 27 (representing 12 percent of the population served by IHS) of the 145 IHS service units that report data to the IHS because the data were incomplete. Data on non-Hispanic whites are from the 1995 National Health Interview Survey.

Source: R�os Burrows (1999, July 26).10 [20]

In Pima Indians, the most widely studied American Indian group, the prevalence of type 2 diabetes was approximately 50 percent in individuals age 30 to 64.1 [11]

During the period from 1986 to 1993, the prevalence of diabetes in Alaska Natives for all ages (adjusted to the 1980 U.S. population) increased by 29 percent, from 15.2 to 19.6 cases per 1,000 people.10 [20] Of these, most had type 2 diabetes.

The prevalence of type 2 diabetes in Alaska Natives varies by subgroup:

  • Eskimo groups (Inupiaq Eskimos in the northern and northwestern coastal areas and Yup'ik Eskimos in the southwestern coastal regions and St. Lawrence Island) had a prevalence of 12.1 per 1,000 in 1993.2 [12]

  • Indian groups (Athabascan in the interior region; Tlingit, Haida, and Tsimshian in the coastal areas) had a prevalence of 24.3 per 1,000 in 1993.2 [12]

  • Aleut groups (residents of the Aleutian Islands, the Pribilof Islands, the western tip of the Alaska Peninsula, the Kodiak area, and the southcentral coastal areas) had a prevalence of 32.6 per 1,000 in 1993.2 [12]

Type 1 Diabetes

Type 1 diabetes is relatively rare in American Indians and Alaska Natives. Most cases of type 1 diabetes are seen in people who have both American Indian and Caucasian heritage.1 [11]


What Risk Factors Increase the Chance That American Indians and Alaska Natives Will Develop Type 2 Diabetes?

Two categories of risk factors increase the chance of type 2 diabetes. The first is genetics. The second is medical and lifestyle risk factors, including obesity, diet, and physical inactivity. Individuals with impaired glucose tolerance, impaired fasting glucose, or insulin resistance are at higher risk of progressing to diabetes.

Genetic Risk Factors

Genetic background is a determining factor in the prevalence of type 2 diabetes. In both the Choctaw Indians and the Pima Indians, the more full-blooded individuals were found to have the highest prevalence of type 2 diabetes, as compared with those of more mixed heritage.1 [11] In Pima Indians, diabetes rates were found to be highest in children whose parents developed diabetes at an early age.1 [11]

Although the specific genes responsible for the inheritance of type 2 diabetes have not been located, NIDDK scientists studying the Pima Indians have identified a gene called FABP2 that may play a role in insulin resistance.11 [21] More recent studies have shown that a variant more common in Pimas than Caucasians in the PPPIR3 gene is associated with type 2 diabetes and insulin resistance.12 [22]

Medical and Lifestyle Risk Factors


How Does Diabetes Affect American Indian and Alaska Native Women During Pregnancy?

Both long- and short-term consequences of diabetes during pregnancy are evident in American Indians and Alaska Natives. Congenital abnormalities in infants born to women with type 2 diabetes are as common as those observed in women with type 1 diabetes. Other complications seen in pregnancies in women with type 2 diabetes included increased rates of toxemia and perinatal mortality.1 [11]

Gestational diabetes, in which blood glucose levels are elevated above normal during pregnancy, occurs in about 2 to 5 percent of all American pregnant women. Perinatal problems such as macrosomia (large body size) and neonatal hypoglycemia (low blood sugar) are higher in babies born to women with gestational diabetes. Although blood glucose levels generally return to normal after childbirth, an increased risk of developing gestational diabetes in future pregnancies remains. In addition, studies show that many women with gestational diabetes will develop type 2 diabetes later in life.

The prevalence of gestational diabetes in certain groups of American Indians and Alaska Natives is as follows:

Followup studies of American Indian women with gestational diabetes found a high risk of developing subsequent diabetes: 27.5 percent of Pima Indian women developed diabetes within 4 to 8 years, and 30 percent of Zuni Indian women developed diabetes within 6 months to 9 years after pregnancy.1 [11]

Longitudinal studies of diabetes in Pima Indians have shown that adult offspring of women with diabetes during pregnancy have significantly higher rates of diabetes than adult offspring of women without diabetes, showing the possible effect of the diabetic intrauterine environment. In fact, 45 percent of adult offspring of Pima Indian women who were diagnosed with type 2 diabetes predating pregnancy developed diabetes by age 20 to 24. In comparison, only 1.4 percent of adult offspring of women without diabetes during pregnancy went on to develop diabetes by age 24.16 [26] The strongest single risk factor for diabetes in Pima children was exposure to diabetes in utero.3 [13]


How Does Diabetes Affect Cardiovascular Health in American Indians and Alaska Natives?


How Do Diabetes Complications Affect American Indians and Alaska Natives?


Does Diabetes Cause an Inordinate Number of Deaths in American Indians and Alaska Natives?

From 1984 to 1986, diabetes was the sixth leading cause of death among American Indians and Alaska Natives in the United States.20 [30]

Because mortality rates are based on the underlying cause of death on death certificates, the impact of diabetes on mortality among American Indians and Alaska Natives has been underestimated. Diabetes contributes to several of the leading causes of death in American Indians: heart disease, cerebrovascular disease, pneumonia, and influenza. In addition, one study found that American Indian heritage was underreported on death certificates by 65 percent. Between 1986 and 1988, the adjusted mortality rate for diabetes in American Indians was 4.3 times the rate in non-Hispanic whites.1 [11] Age- and sex-adjusted death rate studies of Pima Indians from 1975 to 1984 found that the mortality rate for diabetes was nearly 12 times greater than the 1980 mortality rate for all races in the United States.1 [11] Both the duration of the disease and the presence of proteinuria (indicating kidney disease) were factors associated with increased mortality.

According to the Alaska Area Native Health Service, the mortality rate for diabetes in Alaska Natives from 1986 to 1993 was 43.2 per 1,000 person-years of diabetes. Average age at death was 70.3 years. Mortality rates were similar for Aleuts, Eskimos, and Indians.2 [12]


Addressing the Problem of Diabetes in American Indians

In 1996, NIDDK launched its Diabetes Prevention Program (DPP). The goal of this research effort was to learn how to prevent or delay type 2 diabetes in people with impaired glucose tolerance (IGT), a strong risk factor for type 2 diabetes.

The findings of the DPP, which were released in August 2001, showed that people at high risk for type 2 diabetes could sharply lower their chances of developing the disease through diet and exercise. In addition, treatment with the oral diabetes drug metformin also reduced diabetes risk, though less dramatically. These results were so striking that the DPP's external data monitoring board advised ending the trial early.

Participants randomly assigned to intensive lifestyle intervention reduced their risk of getting type 2 diabetes by 58 percent. On average, this group maintained their physical activity at 30 minutes per day, usually with walking or other moderate intensity exercise, and lost 5 to 7 percent of their body weight. Participants randomized to treatment with metformin reduced their risk of getting type 2 diabetes by 31 percent.

Of the 3,234 participants enrolled in the DPP, 45 percent were from minority groups that suffer disproportionately from type 2 diabetes: African Americans, Hispanic Americans, Asian Americans and Pacific Islanders, and American Indians. The trial also recruited other groups known to be at higher risk for type 2 diabetes, including individuals age 60 and older, women with a history of gestational diabetes, and people with a first-degree relative with type 2 diabetes. Participants ranged from age 25 to 85, with an average age of 51.

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Lifestyle intervention successfully reduced the risk of getting type 2 diabetes for both men and women, and across all the ethnic groups. It reduced the development of diabetes in people age 60 and older by 71 percent. Metformin was also effective in men and women and in all the ethnic groups, but was relatively ineffective in the older volunteers and in those who were less overweight.

Researchers will continue to analyze the data to determine whether the interventions reduced cardiovascular disease and atherosclerosis, major causes of death in people with type 2 diabetes. The DPP is the first major trial to show that diet and exercise can effectively delay diabetes in a diverse American population of overweight people with IGT.

Points To Remember

  • About half of American Indian adults have diabetes; most have type 2 diabetes. Rates vary markedly among tribes.

  • Type 1 diabetes in American Indian and Alaska Native youth is relatively rare; however, recent reports highlight an increasing incidence of type 2 diabetes in children and adolescents.

  • American Indians and Alaska Natives have genetic, medical, and lifestyle risk factors for type 2 diabetes.

  • American Indians and Alaska Natives with diabetes have a high incidence of diabetes complications such as eye and kidney disease, cardiovascular disease, and lower extremity amputations.

  • Cardiovascular disease was the leading cause of death in American Indians, and diabetes is a high contributing risk factor for cardiovascular disease.

References

  1. Gohdes, D. (1995). Diabetes in North American Indians and Alaska Natives. In National Diabetes Data Group, Diabetes in America (NIH Publication No. 95-1468, 2nd ed., pp. 683-701. Bethesda, MD: National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health.
  2. Schraer, C. D., Adler, A. I., Mayer, A. M., Halderson, K. R., & Trimble, B. A. (1997). Diabetes complications and mortality among Alaska Natives: 8 years of observation. Diabetes Care, 20(3), 314-316.
  3. Dabelea, D., Hanson, R. L., Bennett, P. H., Roumain, J., Knowler, W. C., & Pettitt, D. J. (1998). Increasing prevalence of type II diabetes in American Indian children. Diabetologia, 41(8), 904-910.
  4. Expert Committee on the Diagnosis and Classification of Diabetes Mellitus. (1997). Report of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus. Diabetes Care, 20(7), 1183-1197.
  5. National Diabetes Information Clearinghouse. (1999). Diabetes statistics (NIH Publication No. 99-3926) [Fact sheet]. Washington, DC: U.S. Government Printing Office.
  6. Lee, E. T., Howard, B. V., Savage, P. J., Cowan, L. D., Fabsitz, R. R., Oopik, A. J., Yeh, J., Go, O., Robbins, D. C., & Welty, T. K. (1995). Diabetes and impaired glucose tolerance in three American Indian populations aged 45-74 years. Diabetes Care, 18(5), 599-610.
  7. Will, J. C., Strauss, K. F., Mendlein, J. M., Ballew, C., White, L., & Peter, D. G. (1997). Diabetes mellitus among Navajo Indians: Findings from the Navajo Health and Nutrition Survey. Journal of Nutrition, 127(Suppl. 10), 2106S-2113S.
  8. Rosenbloom, A. L., Joe, J. R., Young, R. S., & Winter, W. E. (1999). Emerging epidemic of type 2 diabetes in youth. Diabetes Care, 22(2), 345-354.
  9. R�os Burrows, N. (1999, July 23). Data based on personal communication. Indian Health Service, Headquarters Diabetes Program, and Centers for Disease Control and Prevention, Division of Diabetes Translation.
  10. R�os Burrows, N. (1999, July 26). Data based on personal communication. IndianHealth Service, Headquarters Diabetes Program, and Centers for Disease Control and Prevention, Division of Diabetes Translation.
  11. Baier, L. J., Sacchettini, J. C., Knowler, W. C., Eads, J., Paolisso, G., Tataranni, P. A., Mochizuki, H., Bennett, P. H., Bogardus, C., & Prochazka, M. (1995). An amino acid substitution in the human intestinal fatty acid binding protein is associated with increased fatty acid binding, increased fat oxidation, and insulin resistance. Journal of Clinical Investigation, 95(3), 1281-1287.
  12. Xia, J., Scherer, S. W., Cohen, P. T. W., Majer, M., Xi, T., Norman, R. A., Knowler, W. C., Bogardus, C., Prochazka, M. (1998). A common variant in PPP1R3 associated with insulin resistance and type 2 diabetes. Diabetes, 47(9), 1519-1524.
  13. National Institute of Diabetes and Digestive and Kidney Diseases. (1995). The Pima Indians: Pathfinders for health (NIH Publication No. 95-3821) [Booklet]. Washington, DC: U.S. Government Printing Office.
  14. Carter, J. S., Pugh, J. A., & Monterrosa, A. (1996). Non-insulin-dependent diabetes mellitus in minorities in the United States. Annals of Internal Medicine, 125(3), 221-232.
  15. Knowler, W. C., Saad, M. F., Pettitt, D. J., Nelson, R. G., & Bennett, P. H. (1993). Determinants of diabetes mellitus in the Pima Indians. Diabetes Care, 16(Suppl. 1), 216-227.
  16. Pettitt, D. J., Aleck, K. A., Baird, R. H., Carraher, M. J., Bennett, P. H., & Knowler, W. C. (1988). Congenital susceptibility to NIDDM: Role of intrauterine environment. Diabetes, 37(5), 622-628.
  17. Welty, T. K., Lee, E. T., Yeh, J., Cowan, L. D., Go, O., Fabsitz, R. R., Le, N., Oopik, A. J., Robbins, D. C., & Howard, B. V. (1995). Cardiovascular disease risk factors among American Indians: The Strong Heart Study. American Journal of Epidemiology, 142(3), 269-287.
  18. Lee, E. T., Cowan, L. D., Welty, T. K., Sievers, M., Howard, W. J., Oopik, A., Wang, W., Yeh, J., Devereux, R. B., Thoades, E. R., Fabsitz, R. R., Go, O., & Howard, B. V. (1998). All-cause mortality and cardiovascular disease mortality in three American Indian populations, aged 45-74, 1984-1988. American Journal of Epidemiology, 147(11), 995-1008.
  19. Rith-Najarian, S. J., Stolusky, T., & Gohdes, D. M. (1992). Identifying diabetic patients at high risk for lower-extremity amputation in a primary health care setting: A prospective evaluation of simple screening criteria. Diabetes Care, 15(10), 1386-1389.
  20. Gohdes, D., Kaufman, S., & Valway, S. (1993). Diabetes in American Indians. Diabetes Care, 16(Suppl. 1), 239-243.


Original NDIC Article Date: October 1999; Updated: August 2001