Diabetes in North American Indians and Alaska Natives
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Chapter 34 Diabetes in North American Indians and Alaska Natives Dorothy Gohdes, MD SUMMARY he epidemic of non-insulin-dependent dia- IDDM are found in individuals with significant non- betes mellitus (NIDDM) in Native American Native American ancestry. communities has occurred primarily during the second half of this century. Although Much of our understanding of the natural history of TNIDDM has a genetic component, with rates highest NIDDM in North American Indians is derived from in full-blooded Native Americans, the incidence and the longitudinal epidemiologic studies of the Pima prevalence of the disease have increased dramatically Indians in southern Arizona. The relationship of obe- as traditional lifestyles have been abandoned in favor sity to subsequent diabetes as described in studies of of westernization, with accompanying increases in the Pimas is present in all Native American popula- body weight and diminished physical activity. Anthro- tions. Native American communities experience high pologic studies have shown that several tribes per- rates of microvascular complications from diabetes, ceive diabetes as an assault from outside the commu- although the rates of cardiovascular disease differ nity. Diabetes was once described as benign in Ameri- from tribe to tribe. The differences may reflect geneti- can Indians; now, diabetes and its complications are cally based variations in lipid metabolism or other major contributors to morbidity and mortality in all coronary risk factors or, alternatively, differences in Native American populations, except the isolated Arc- lifestyle. The extent of diabetes in Native American tic groups whose lifestyles remain relatively un- communities today demands public health programs changed. Insulin-dependent diabetes mellitus that incorporate specific psychosocial and cultural (IDDM) is rare in Native Americans and most cases of adaptations for individual tribes. • • • • • • • of North America are young, with a median age in INTRODUCTION 1990 of 26 years, compared with 33 years for all races in the United States. In addition, Native Americans Native Americans are a diverse group of people whose are disadvantaged both economically and education- ancestors lived in North America before the European ally compared with the general U.S. population. settlement. In the United States alone, there are more than 500 tribal organizations. In addition to their PREVALENCE tribal affiliations, Native Americans are often distin- guished by language and/or cultural groups, some of which extend across both the United States and Can- Because American Indians living on reservations are ada. Contemporary Native American populations live not included in U.S. national health surveys, data on in urban areas and on reservations or reserves in both the prevalence of diabetes in Native Americans resid- countries. In the United States, ~1.9 million individu- ing in the United States are limited. Rates have been als identified themselves in the 1990 Census as Ameri- estimated from case registries maintained at health can Indian or Alaska Native, but only 1.2 million of facilities, glucose testing at a community level, and these resided in the 33 reservation states served by the surveys of self-reported diabetes. In the United States Indian Health Service (IHS), an agency of the U.S. and Canada, prevalence estimates for diagnosed dia- Public Health Service1,2. Few data exist on the health betes are available from health care facilities where of urban Native Americans in either the United States care is provided at no charge to Native Americans. The or Canada. Overall, the Native American populations IHS estimated the rates of diagnosed diabetes from 683 Figure 34.1 Table 34.1 Indian Health Service Areas Diagnosed Diabetes in Native American Communities in the U.S. and Canada, All Ages, 1987 Crude prevalence Age-adjusted per 1,000 prevalence per 1,000 United States Tucson 76 119 Aberdeen 60 105 Phoenix 65 104 Albuquerque 55 94 Bemidji 53 92 Nashville 63 87 Billings 50 86 Oklahoma 49 60 Navajo 32 56 Portland 29 49 Alaska 9 15 All IHS 45 69 Canada Source: Indian Health Service Atlantic 43 87 Quebec 29 48 ambulatory care visits that covered 86% of the esti- Ontario 46 76 mated 1 million American Indians served through the Manitoba 28 57 IHS in 19873. Duplicate records were excluded by Saskatchewan 17 39 Alberta 22 51 using unique patient identifiers. Rates were calculated Yukon 7 12 for the regions shown in Figure 34.1. A similar esti- NW Terr. Indian 5 8 mate covering 76% of the Inuit and Canadian Natives NW Terr. Inuit 3 4 living on reserves was also undertaken in 1987, using British Columbia 9 16 cases known to the Medical Services Branch of the U.S. rates are age-adjusted to the 1980 U.S. population; Canada’s rates are Department of National Health and Welfare in Can- age-adjusted to the 1985 Canadian population. ada4. Crude and age-adjusted rates of diabetes from these two surveys are shown in Table 34.13,4. The rates Source: References 3 and 4 decreased toward the north and west in Canada. Al- though a similar trend was not apparent in the United ably due to an increased incidence and cannot be States, rates in the far northwest were relatively low in attributed solely to longer survival of diabetic indi- both countries. Rates of diabetes were higher in viduals27. Figure 34.2 shows the prevalence of diabe- women than in men in all Canadian provinces, a trend tes in Pima Indians in each of three time periods since also found for the United States in current diabetes 196527. Appendix 34.1 compares prevalence of diabe- estimates by the IHS. Women had higher rates of tes in Pima Indian men and women with prevalence of diabetes (13.2%) than men (11.0%) in a special medi- NIDDM in a sample of U.S. white men and women. cal expenditure survey of American Indians eligible for IHS services conducted in 19875. In the survey, the age- and sex-adjusted diabetes rate in individuals age DETERMINANTS OF DIABETES ≥19 years was 12.2%, compared with 5.2% in the general U.S. population. A summary of published studies6-24 of diabetes prevalence in individual tribes The longitudinal studies of diabetes conducted in in North America is presented in Table 34.2. These Pima Indians since 1965 have provided extensive in- studies used criteria of the World Health Organization formation about NIDDM and its natural history in (WHO) and the U.S. National Diabetes Data Group American Indians. The form of diabetes that affects (NDDG) for diagnosis of NIDDM25,26. Pimas is characterized biochemically and immu- nologically as NIDDM, an observation that confirms Striking increases in the prevalence of diabetes in the paucity of IDDM also noted in other tribes27,30. recent years have been described in Pima Indians and other tribes11,22,27- 29 . Because the incidence of diabetes has also increased in Pimas, and presumably in other tribes, the increased prevalence in many tribes is prob- 684 Table 34.2 Prevalence of Diabetes in North America Native Populations by Region Reservation/Location Tribe Age Date Rate/1,000 Adjustment Method Reference Southwest Tohono O’odham, AZ Tohono O’odham ≥18 1985-86 183 None Case registry 6 w/record review Gila River, AZ Pima 30-64 1982-87 500 Age Biennial community 7 World pop. screening New Mexico Pueblo ≥35 1985 213 None Case registry 8 (Rio Grande) w/record review Zuni, NM Zuni ≥35 1985 282 None Case registry 8 w/record review Jicarilla Apache, NM Apache ≥35 1985 98 None Case registry 8 w/record review Mescalero Apache, NM Apache ≥35 1985 164 None Case registry 8 w/record review Navajo, NM Navajo ≥35 1985 165 None Case registry 8 w/record review Arizona and New Mexico Apache ≥15 1987 101 Age Outpatient records 9 reservations U.S. 1980 not verified Navajo, AZ and NM Navajo ≥15 1987 72 Age Outpatient records 9 U.S. 1980 not verified Navajo, AZ Navajo 20-74 1989 165 Age/sex Case registry 10 U.S. 1980 community screening Navajo, AZ Navajo ≥20 1988 124 Age Community sample 11 U.S. 1980 w/screening Rocky Mountain West Fort Hall, ID Shoshone/Bannock All 1987 95 Age/sex Case registry 12 U.S. 1980 w/chart review Nez Perce, ID Nez Perce All 1987 105 Age/sex Case registry 12 U.S. 1980 w/chart review Blackfeet, MT Blackfeet ≥15 1986 168 Age ≥15 Case registry 13 U.S. 1980 w/chart review Crow, MT Crow ≥15 1986 85 Age ≥15 Case registry 13 U.S. 1980 w/chart review Fort Belknap, MT Assiniboine/ ≥15 1986 118 Age ≥15 Case registry 13 Gros Ventre U.S. 1980 w/chart review Fort Peck, MT Assiniboine/Sioux ≥15 1986 173 Age ≥15 Case registry 13 U.S. 1980 w/chart review Northern Cheyenne, MT Northern Cheyenne ≥15 1986 59 Age ≥15 Case registry 13 U.S. 1980 w/chart review Wind River, WY Shoshone/Arapaho ≥15 1986 125 Age ≥15 Case registry 13 U.S. 1980 w/chart review Utah and Colorado Ute ≥15 1987 124 Age Outpatient records 9 U.S. 1980 not verified Northern Plains Cheyenne River, SD Sioux All 1987 106 Age Outpatient records 14 U.S. 1980 not verified Crow Creek, Sioux All 1987 83 Age Outpatient records 14 Lower Brule, SD U.S. 1980 not verified Devil’s Lake, ND Sioux All 1987 111 Age Outpatient records 14 U.S. 1980 not verified Pine Ridge, SD Sioux All 1987 70 Age Outpatient records 14 U.S. 1980 not verified Rosebud, SD Sioux All 1987 82 Age Outpatient records 14 U.S. 1980 not verified Sisseton/Wahpeton, SD Sioux All 1987 64 Age Outpatient records 14 U.S.