Reduced prevalence of impaired glucose tolerance and no change in prevalence of diabetes despite increasing BMI among Aboriginal people from a group of remote homeland communities

Diet change and sustainability in Indigenous areas: characteristics, drivers, and impacts of diet change in Gunayala, Panama

Many Indigenous communities around the world have been experiencing rapid and profound diet changes. This case report uses a Sustainability Science lens to understand the characteristics of diet change in Indigenous Gunas communities of Panama, as well as its drivers and sustainability impacts. We use primary information collected through interviews with 30 experts and 232 household surveys in three Gunas islands  characterised by different levels of development, western influence, and cultural erosion. We observe a rapid westernization of diets that has been mainly driven by closer interaction with tourists and the Panamanian society, as well as broader development processes. However, this diet change has a series of intersecting sustainability impacts related to food security, health, and socio-cultural and environmental change. It is necessary to understand the intersection of these phenomena when designing programs and interventions that seek to prevent or mitigate negative diet changes in Gunayala, and other  Indigenous contexts more broadly.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11625-023-01325-0.

Long-term effectiveness of a lifestyle intervention on the prevention of type 2 diabetes in a middle-income country

This study aims to assess the effects of a community-based lifestyle intervention program on the incidence of type 2 diabetes (T2D). For this purpose, three communities in Tehran were chosen; one community received a face-to-face educational session embedded in a long-term community-wide lifestyle intervention aimed at supporting lifestyle changes. We followed up 9,204 participants (control: 5,739, intervention: 3,465) triennially from 1999 to 2015 (Waves 1-5). After a median follow-up of 3.5 years (wave 2), the risk of T2D was 30% lower in the intervention community as compared with two control communities by (Hazard-ratio: 0.70 [95% CI 0.53; 0.91]); however, the difference was not statistically significant in the following waves. After a median follow-up of 11.9 years (wave 5), there was a non-significant 6% reduction in the incidence of T2D in the intervention group as compared to the control group (Hazard-ratio: 0.94 [0.81, 1.08]). Moreover, after 11.9 years of follow-up, the intervention significantly improved the diet quality measured by the Dietary Approaches to Stop Hypertension concordance (DASH) score. Mean difference in DASH score in the intervention group versus control group was 0.2 [95% CI 0.1; 0.3]. In conclusion, the intervention prevented T2D by 30% in the short-term (3.5 years) but not long-term; however, effects on improvement of the diet maintained in the long-term.Registration: This study is registered at IRCT, a WHO primary registry ( https://irct.ir ). The registration date 39 is 2008-10-29 and the IRCT registration number is IRCT138705301058N1.

Effect of nutrition interventions on diet-related and health outcomes of Aboriginal and Torres Strait Islander Australians: a systematic review

OBJECTIVE

To review the literature on nutrition interventions and identify which work to improve diet-related and health outcomes in Australian Aboriginal and Torres Strait Islander people.

STUDY DESIGN

Systematic review of peer-reviewed literature.

DATA SOURCES

MEDLINE, PubMed, Embase, Science Direct, CINAHL, Informit, PsychInfo and Cochrane Library, Australian Indigenous Health InfoNet.

STUDY SELECTION

Peer-reviewed article describing an original study; published in English prior to December 2017; inclusion of one or more of the following outcome measures: nutritional status, food/dietary/nutrient intake, diet-related biomedical markers, anthropometric or health measures; and conducted with Australian Aboriginal and Torres Strait Islander people.

DATA EXTRACTION AND SYNTHESIS

Two independent reviewers extracted data and applied the Quality Assessment Tool for Quantitative Studies from the Effective Public Health Practice Project. A purpose designed tool assessed community engagement in research, and a framework was applied to interventions to report a score based on numbers of settings and strategies. Heterogeneity of studies precluded a meta-analysis. The effect size of health outcome results were estimated and presented as forest plots.

RESULTS

Thirty-five articles (26 studies) met inclusion criteria; two rated moderate in quality; 12 described cohort designs; 18 described interventions in remote/very remote communities; none focused solely on urban communities; and 11 reported moderate or strong community engagement. Six intervention types were identified. Statistically significant improvements were reported in 14 studies of which eight reported improvements in biochemical/haematological markers and either anthropometric and/or diet-related outcomes.

CONCLUSIONS

Store-based intervention with community health promotion in very remote communities, fiscal strategies and nutrition education and promotion programmes show promise. Future dietary intervention studies must be rigorously evaluated, provide intervention implementation details explore scale up of programmes, include urban communities and consider a multisetting and strategy approach. Strong Aboriginal and Torres Strait Islander community engagement is essential for effective nutrition intervention research and evaluation.

PROSPERO REGISTRATION NUMBER

CRD42015029551.

Nutritional predictors of successful chronic disease prevention for a community cohort in Central Australia

OBJECTIVE

To investigate biomarkers of nutrition associated with chronic disease absence for an Aboriginal cohort.

DESIGN

Screening for nutritional biomarkers was completed at baseline (1995). Evidence of chronic disease (diabetes, CVD, chronic kidney disease or hypertension) was sought from primary health-care clinics, hospitals and death records over 10 years of follow-up. Principal components analysis was used to group baseline nutritional biomarkers and logistic regression modelling used to investigate associations between the principal components and chronic disease absence.

SETTING

Three Central Australian Aboriginal communities.

SUBJECTS

Aboriginal people (n 444, 286 of whom were without chronic disease at baseline) aged 15-82 years.

RESULTS

Principal components analysis grouped twelve nutritional biomarkers into four components: 'lipids'; 'adiposity'; 'dietary quality'; and 'habitus with inverse quality diet'. For the 286 individuals free of chronic disease at baseline, lower adiposity, lower lipids and better dietary quality components were each associated with the absence at follow-up of most chronic diseases examined, with the exception of chronic kidney disease. Low 'adiposity' component was associated with absence of diabetes, hypertension and CVD at follow-up. Low 'lipid' component was associated with absence of hypertension and CVD, and high 'dietary quality' component was associated with absence of CVD at follow-up.

CONCLUSIONS

Lowering or maintenance of the factors related to 'adiposity' and 'lipids' to healthy thresholds and increasing access to a healthy diet appear useful targets for chronic disease prevention for Aboriginal people in Central Australia.

Diabetes prevalence and determinants in Indigenous Australian populations: A systematic review

AIMS

To perform a systematic review of the prevalence of diabetes and impaired glucose tolerance (IGT) in Indigenous Australians in order to clarify overall patterns, by determinants such as age, gender, region, ethnicity and remoteness.

METHODS

The OVID interface to Medline and the Australian Indigenous HealthInfoNet databases were systematically searched from years 1997 to 2010. Studies reporting diabetes prevalence were included if they used population-based samples of Indigenous Australians. Diagnosis of diabetes was based on self-report or standard diagnostic criteria.

RESULTS

Twenty-four studies were included. The diabetes prevalence ranged from 3.5 to 33.1%; IGT estimates ranged from 4.7 to 21.1%. Prevalence was greater among Indigenous Australian women compared to men, the Northern Territory's Top End compared to Central Australia, Torres Strait Islanders compared to Aboriginals, older (≥35 years) compared to younger (<35 years) age groups, and remote compared to urban settings. Patterns of IGT prevalence were similar to those observed for diabetes.

CONCLUSIONS

Although the prevalence of diabetes and IGT is high, there appears to be considerable variation in prevalence between different segments of the Australian Indigenous population. Data on diabetes prevalence in the urban Australian Indigenous population is lacking, despite accounting for almost three quarters of the total population.

Integrating an ecological approach into an Aboriginal community-based chronic disease prevention program: a longitudinal process evaluation

Background

Public health promotes an ecological approach to chronic disease prevention, however, little research has been conducted to assess the integration of an ecological approach in community-based prevention programs. This study sought to contribute to the evidence base by assessing the extent to which an ecological approach was integrated into an Aboriginal community-based cardiovascular disease (CVD) and type 2 diabetes prevention program, across three-intervention years.

Methods

Activity implementation forms were completed by interview with implementers and participant observation across three intervention years. A standardised ecological coding procedure was applied to assess participant recruitment settings, intervention targets, intervention strategy types, extent of ecologicalness and organisational partnering. Inter-rater reliability for two coders was assessed at Kappa = 0.76 (p < .0.001), 95% CI (0.58, 0.94).

Results

215 activities were implemented across three intervention years by the health program (HP) with some activities implemented in multiple years. Participants were recruited most frequently through organisational settings in years 1 and 2, and organisational and community settings in year 3. The most commonly utilised intervention targets were the individual (IND) as a direct target, and interpersonal (INT) and organisational (ORG) environments as indirect targets; policy (POL), and community (COM) were targeted least. Direct (HP→ IND) and indirect intervention strategies (i.e., HP→ INT→ IND, HP→ POL → IND) were used most often; networking strategies, which link at least two targets (i.e., HP→[ORG-ORG]→IND), were used the least. The program did not become more ecological over time.

Conclusions

The quantity of activities with IND, INT and ORG targets and the proportion of participants recruited through informal cultural networking demonstrate community commitment to prevention. Integration of an ecological approach would have been facilitated by greater inter-organisational collaboration and centralised planning. The upfront time required for community stakeholders to develop their capacity to mobilise around chronic disease is at odds with short-term funding cycles that emphasise organisational accountability.

Smoking, nutrition, alcohol and physical activity interventions targeting Indigenous Australians: rigorous evaluations and new directions needed

OBJECTIVE

To describe and critique methodological aspects of interventions targeting reductions in smoking, poor nutrition, alcohol misuse and physical inactivity (SNAP risk factors) among Indigenous Australians.

METHODS

An electronic search of eight databases and a manual search of reference lists of literature reviews and reference libraries for Indigenous-specific intervention studies published in peer-reviewed journals (January 1990 to August 2007) were undertaken. Alcohol, smoking, nutrition or physical activity needed to be the primary focus of the study and the intervention needed to specifically target Indigenous Australians.

RESULTS

Twenty studies were selected for inclusion in the review. Methodologically, few studies employed randomisation or a control group, most omitted important details (e.g. costs), some did not report process measures (e.g. attrition rates), and some did not use validated measures. Two-thirds of interventions were implemented at the community level and employed multiple strategies.

CONCLUSION

There is a need for more rigorous evaluations of interventions targeting reductions in SNAP risk factors among Indigenous Australians, and to establish the reliability and validity of measures to quantify their effect.

IMPLICATIONS

It may be beneficial for future Indigenous-specific intervention research to focus on the evaluation of secondary prevention to complement the current concentration of effort targeting primary prevention. Community-wide interventions, combining strategies of greater intensity for high risk individuals with those of less intensity targeting lower risk individuals, might also offer considerable promise.

The prevention of type 2 diabetes

Type 2 diabetes mellitus (T2DM) affects more than 7% of adults in the US and leads to substantial personal and economic burden. In prediabetic states insulin secretion and action--potential targets of preventive interventions--are impaired. In trials lifestyle modification (i.e. weight loss and exercise) has proven effective in preventing incident T2DM in high-risk groups, although weight loss has the greatest effect. Various medications (e.g. metformin, thiazolidinediones and acarbose) can also prevent or delay T2DM. Whether diabetes-prevention strategies also ultimately prevent the development of diabetic vascular complications is unknown, but cardiovascular risk factors are favorably affected. Preventive strategies that can be implemented in routine clinical settings have been developed and evaluated. Widespread application has, however, been limited by local financial considerations, even though cost-effectiveness might be achieved at the population level.

Australian Aboriginal people and Torres Strait Islanders have an atherogenic lipid profile that is characterised by low HDL-cholesterol level and small LDL particles

AIM

To characterise lipid profiles for Australian Aboriginal people and Torres Strait Islanders.

METHODS

Community-based, cross-sectional surveys in 1995-1997 including: 407 female and 322 male Australian Aboriginal people and 207 female and 186 male Torres Strait Islanders over 15 years old. A comparator of 78 female (44 with diabetes) and 148 male (73 with diabetes) non-indigenous participants recruited to clinical epidemiological studies was used. Lipids were determined by standard assays and LDL diameter by gradient gel electrophoresis.

RESULTS

Diabetes prevalence was 14.8% and 22.6% among Aboriginal people and Torres Strait Islanders, respectively. LDL size (mean [95% CI (confidence interval)]) was smaller (P<0.05) in non-diabetic Aboriginal (26.02 [25.96-26.07] nm) and Torres Strait Islander women (26.01 [25.92-26.09] nm) than in non-diabetic non-indigenous women (26.29 [26.13-26.44] nm). LDL size correlated (P<0.0005) inversely with triglyceride, WHR, and fasting insulin and positively with HDL-cholesterol. HDL-cholesterol (mean [95% CI] mmol/L) was lower (P<0.0005) in indigenous Australians than in non-indigenous subjects, independent of age, sex, diabetes, WHR, insulin, triglyceride, and LDL size: Aboriginal (non-diabetic women, 0.86 [0.84-0.88]; diabetic women, 0.76 [0.72-0.80]; non-diabetic men, 0.79 [0.76-0.81]; diabetic men, 0.76 [0.71-0.82]); Torres Strait Islander (non-diabetic women, 1.00 [0.95-1.04]; diabetic women, 0.89 [0.83-0.96]; non-diabetic men, 1.00 [0.95-1.04]; diabetic men, 0.87 [0.79-0.96]); non-indigenous (non-diabetic women, 1.49 [1.33-1.67]; diabetic women, 1.12 [1.03-1.21]; non-diabetic men, 1.18 [1.11-1.25]; diabetic men, 1.05 [0.98-1.12]).

CONCLUSIONS

Indigenous Australians have a dyslipidaemia which includes small LDL and very low HDL-cholesterol levels. The dyslipidaemia was equally severe in both genders. Strategies aimed at increasing HDL-cholesterol and LDL size may reduce high CVD risk for indigenous populations.

Socioeconomic status and diabetes among urban Indigenous Australians aged 15-64 years in the DRUID study

BACKGROUND

Diabetes is associated with lower socioeconomic status (SES) in developed countries, but the reverse is true in developing countries. Little is known about the relationship between SES and diabetes among Indigenous populations in developed countries.

DESIGN

We examined the relationship between measures of SES and the prevalence of diabetes in the DRUID Study, a cross-sectional study of urban Indigenous Australian volunteers in the Darwin region.

RESULTS

Among 777 participants aged 15-64 years included in the analysis, 17.1% had diabetes, ranging from 2.0% among those aged 15-24 years to 50.8% of those aged 55-64 years. After adjusting for age and sex, diabetes was significantly more common among those of lower SES, whether measured by housing tenure, household income, or employment status. For example, compared with those living in a household that was owned/being purchased by its occupants, the relative odds of diabetes was 2.66 (95% confidence interval 1.71-4.15) for those living in rented/other accommodation. The inverse relationship between SES and diabetes was present even among those who had not previously been diagnosed with diabetes. The relationship between disadvantage and diabetes was not mediated to any great degree by obesity.

CONCLUSIONS

The relationship between SES and diabetes among Indigenous Australians in this study is consistent with the patterns observed in developed countries, rather than those in some developing countries.

Diabetes in Indigenous Australians: possible ways forward

Reducing the burden of diabetes will require action well beyond the health service sphere.

Hemostatic factors in Australian Aboriginal and Torres Strait Islander populations

Hemostatic processes are important in precipitating myocardial infarction and stroke. Elevated plasma fibrinogen is considered a risk factor for cardiovascular diseases (CVDs), but the results of previous studies on the association of plasma factor VIIc activity with CVD and diabetes have been inconsistent. The aim of the present study was to explore the association of plasma fibrinogen and factor VIIc to clinical characteristics and estimated coronary heart disease (CHD) risk in Aboriginal and Torres Strait Islander peoples. Cross-sectional surveys of Australian Aboriginal people (n = 852) and Torres Strait Islanders (n = 276) aged 15 years and older were conducted from 1993 to 1995. Anthropometric characteristics, blood pressure, fasting plasma fibrinogen, factor VIIc, total and high-density lipoprotein cholesterol, triglycerides, and glucose were measured. Levels of fibrinogen (mean, 95% confidence interval) for Aboriginal (3.52, 3.44-3.59 g/L) and Torres Strait Islander people (3.62, 3.49-3.75 g/L) were higher compared with previous reports from other populations. Factor VIIc (mean, 95% confidence interval) was especially high in Torres Strait Islanders (116%, 111%-122%) compared with Aboriginal people (99%, 97%-102%). Fibrinogen increased with age in both ethnic groups and sexes. Fibrinogen was independently associated with female sex, body mass index, renal dysfunction, low levels of high-density lipoprotein cholesterol and diabetes, whereas the independent predictors for factor VIIc were Torres Strait Islander ethnicity, female sex, body mass index, renal dysfunction, and total cholesterol. Average fibrinogen levels were high (>3.5 mg/dL) even for people considered "below average risk of coronary heart disease" according to conventional risk factor levels. For Aboriginal women, levels of fibrinogen and factor VIIc were significantly higher for persons at high risk than those at below average risk. The data suggest that plasma fibrinogen and factor VIIc might be important factors mediating the elevated CVD in Australian Indigenous Peoples. These data may have implications for prevention and treatment of CVD in Australian Indigenous communities.

Could statistical adjustments for age mask the insulin-blood pressure relationship?

Even though conclusive findings regarding the relationship between insulin and blood pressure (BP) have been made, several papers still report on finding weak or non-existing relationships in various population groups. These relationships are often weak, depend on the characteristics of the study population and are usually strongly confounded by obesity and age. Subsequently many investigators adjust via statistical methods for age and measures of obesity (such as body mass index). In the present study four different datasets were used (Australian Aboriginal people (N=675), Torres Strait Islanders (N=369), African women (N=94) and Caucasian women (N=112)) and showed very weak correlations in all groups after statistical adjustments for age and obesity (ranging from r=-0.04 to 0.13). All subjects were then divided into different age groups (15-29 years; 30-40 years; >40 years) and partial correlations were performed within each age group whilst adjusting only for obesity. Results still showed correlations (ranging from r=-0.29 to 0.27) with a similar trend with increasing age. More positive correlations were shown for the youngest groups, and more negative correlations for the oldest groups, with the middle-group (30-40 years) showing the weakest correlations-seeming to be in a transitional phase from a positive to negative correlation. It is therefore suggested that when the relationship between fasting insulin and BP is assessed, age stratification be used and not statistical adjustments.

Leanness and type 2 diabetes in a population of indigenous Australians

OBJECTIVE

To determine the prevalence of type 2 diabetes and its risk factors in a population of indigenous Australians.

RESEARCH DESIGN AND METHODS

A cross-sectional study of 332 indigenous community residents aged 15 years and over with fasting blood samples and anthropometric measurements.

RESULTS

Almost half of the study population (47.3%) was extremely lean (BMI<22 kg/m(2)). Leanness was particularly pronounced in the youngest age group (15<20 years), 78% of which had a BMI<22 kg/m(2). The prevalence of diabetes was 12%. It was highest in those 45-54 years and declined in older aged people. No cases of diabetes were detected in those aged less than 30 years. Diabetes prevalence was strongly linked to BMI and age (age-adjusted odds ratio=24.1, 95% CI 6.0-96.5, p<0.001) for BMI>or=25 kg/m(2) versus BMI<22 kg/m(2). Those with the lowest diabetes risk profile are lean (BMI<22 kg/m(2)) and/or young (age 15-34 years).

CONCLUSIONS

These results highlight that strategies to prevent or delay the onset of diabetes should focus on the maintenance of leanness from adolescence and throughout adult life whilst young people are still in the process of forming lifelong habits.

The metabolic syndrome and changing relationship between blood pressure and insulin with age, as observed in Aboriginal and Torres Strait Islander peoples

AIMS

To determine the prevalence of the metabolic syndrome (MS) among Aboriginal and Torres Strait Islander peoples. A further objective was to investigate the relationships between fasting insulin and blood pressure (BP) within these groups with increasing age.

METHODS

A cross-sectional population-based study included 369 Torres Strait Islanders (residing in Torres Strait and Far North Queensland), and 675 Aborigines from central Australia. Data necessary for classification of MS was collected, including fasting and 2-h glucose and insulin, urinary albumin and creatinine, anthropometric measurements, BP, serum lipids.

RESULTS

The ATPIII criteria classified 43% of Torres Strait Islanders and 44% of Aborigines with MS, whereas 32 and 28%, respectively, had the MS according to WHO criteria. Agreement between the two criteria was only modest (kappa coefficient from 0.28 to 0.57). Factor analyses indicated no cluster including both insulin and BP in either population. Significant correlations (P < 0.05) [adjusted for gender, body mass index (BMI) and waist circumference] were observed between BP and fasting insulin: a positive correlation for Torres Strait Islanders aged 15-29 years, and an inverse correlation for Aborigines aged 40 years and older.

CONCLUSION

Torres Strait Islanders and Aborigines had very high prevalences of the MS. Specific population characteristics (high prevalences of central obesity, dyslipidaemia, renal disease) may make the WHO definition preferable to the ATPIII definition in these population groups. The poor agreement between criteria suggests a more precise definition of the metabolic syndrome that is applicable across populations is required. This study showed an inverse relationship with age for the correlation of BP and fasting insulin.

Receding horizons of health: biocultural approaches to public health paradoxes

Worldwide challenges to health reflect a "paradox of success," whereby both the strengths and the weaknesses of current approaches in public health, epidemiology, and biomedicine have determined the nature of the health problems we now face. In detail, we analyze and illustrate five constituent paradoxes that fuel continued health risk even in the face of success, including: (1) unmasking, (2) local biology, (3) socialization, (4) emerging and reemerging disease, and (5) savage inequity. We trace the pathways behind the paradoxes and their effects on health, and demonstrate that biocultural dynamics are involved in each. Furthermore, we track the roots of health paradox to changes that divert or disrupt pathways for production of health. These analyses contribute to an emerging literature of research and praxis on integrative biocultural models of health.

Cancer incidence and survival for indigenous Australians in the Northern Territory

OBJECTIVE

To compare cancer incidence and survival for the Northern Territory (NT) Indigenous population with that of other Australians, and to assess NT Indigenous incidence time trends.

METHODS

Cancer registry data were used to calculate cancer incidence rate ratios (NT Indigenous to total Australian), the average annual change in NT Indigenous cancer incidence and the relative risk of cancer death after diagnosis of cancer (NT Indigenous to combined Western Australian and Tasmanian cases) for 1991-2001.

RESULTS

For NT Indigenous people, incidence rates were high for cancers of the liver, gallbladder, cervix, vulva and thyroid and, in younger people only, for cancers of the oropharynx, oesophagus, pancreas and lung, but low for cancers of the colon and rectum, breast, ovary, prostate, bladder, kidney, melanoma and lymphoma. Incidence rate ratios ranged from 0.1 for melanoma to 7.4 for liver cancer. Incidence increased for breast and pancreatic cancers. Survival was low for almost all specific cancers examined, and for all cancers combined (relative risk of death 1.9, 95% CI 1.7-2.1).

CONCLUSIONS

Compared with other Australians, NT Indigenous people have higher, and increasing, incidence for some cancers (particularly smoking-related cancers) and lower survival for most.

IMPLICATIONS

Cancer has a greater impact on NT Indigenous people than other Australians. Well-established cancer risk factors should be more effectively tackled in Indigenous people and known effective screening programs more effectively implemented. Research is urgently required into the reasons why survival from cancer in NT Indigenous people is so much lower than in other Australians.

Diabetes care and complications in a remote primary health care setting

Prevalence of complications of type 2 diabetes in a remote Australian Indigenous community was measured as part of a population survey of risk factors for diabetes and cardiovascular disease. Information was obtained from history, clinical examination, blood sample and medical records. Forty-three diabetic participants (six newly diagnosed) were assessed from a sample of 339 (12% diabetes prevalence); mean age 50 (range 31-67), duration of diabetes 5.6 (0-15) years, 40% male. Risk factors/complications: 70% with >/= 25, 50% cigarette smokers, HbA1c 8.5 (S.D. 2.9)%, cholesterol 4.8 (0.8)mmol/l, triglycerides 2.7 (1.6)mmol/l, HDL 0.83 (0.2)mmol/l; 60% had albuminuria (micro 38%, macro 22%), 47% were hypertensive, 7% (n = 2) had retinopathy, 24% had peripheral neuropathy, none had peripheral vascular disease, 14% had documented coronary vascular and one participant cerebrovascular disease. Of 37 with previously diagnosed diabetes: 43% were on aspirin, 65% on metformin, 80% with albuminuria on ACE inhibitors. Four additional diabetic participants (not studied) were receiving renal dialysis elsewhere. The results demonstrate on the one hand, very high indices of cardiovascular risk (smoking, hypertension, dyslipidaemia and albuminuria) and on the other, good quality primary health care providing good detection and follow up management of type 2 diabetic patients.

Community-based lifestyle interventions to prevent type 2 diabetes

OBJECTIVE

To conduct a literature review of community-based interventions intended to prevent or delay type 2 diabetes.

RESEARCH DESIGN AND METHODS

Recently published findings about the potential to prevent or delay type 2 diabetes with intensive lifestyle interventions prompted a literature search for community-based diabetes prevention interventions. The literature review design was a search of databases for publications in 1990-2001 that identified reports on community-based interventions designed to prevent or modify risk factors for type 2 diabetes.

RESULTS

The search revealed 16 published interventions, 8 of which were conducted in the U.S. and involved populations disproportionately burdened by diabetes (e.g., American Indians, Native Hawaiians, Mexican Americans, and African Americans). Of the studies reporting results among youth, there were posttest improvements in intervention groups in knowledge, preventive behaviors, and self-esteem. Among studies reporting results among adults, most reported improvements in intervention groups in knowledge or adoption of regular physical activity. Several investigators offered important reflections about the process of engaging communities and sharing decision making in participatory research approaches, as well as insights about the expectations and limitations of community-based diabetes prevention research. Many of the studies reported limitations in their design, including the lack of control or comparison groups, low response rates or lack of information on nonresponders, or brief intervention periods.

CONCLUSIONS

There is a critical need to conduct and publish reports on well-designed community-based diabetes prevention research and share information on the process, results, and lessons learned. Armed with recent positive findings about diabetes prevention and literature documenting community-based efforts, advocates at local, state, and national levels can collaborate to stem the rising tide of diabetes in communities.

Fasting criteria for screening: test properties and agreement with glucose tolerance

The objective of this study was to characterise test properties and agreement for fasting glucose cut-offs used for screening diabetes in Indigenous Australian communities, across a range of diabetes prevalence. The oral glucose tolerance test (OGTT) was administered to adult volunteers (n=3249) for community-based diabetes screening in isolated settlements (n=25). Two-hour post-load glucose concentration was the 'gold standard' against which test properties were characterised for fasting plasma glucose cut-offs at concentrations of > or = 7.0 mmol/l (ADA criterion) and > or = 7.8 mmol/l (WHO criterion). Test sensitivity (95% CI) was greater for the ADA (72.5%, 67.4-77.1%) versus the WHO criterion (61.5%, 56.1-66.6%). Specificity was high (>98%) using either criterion. The post-test likelihood of diabetes, given a population prevalence of 14.8%, was 89.1% using the ADA criterion, and 94.9% using the WHO criterion. The ADA criterion gave better agreement than did the WHO criterion for diabetes prevalence > or = 8.6%, and the probability of false results was lower using the ADA criterion, when diabetes prevalence was > or = 12.8%. According to the ADA criterion most individuals ascribed false negative results were aged > or = 35 years, overweight/obese, or had impaired fasting glucose. The fasting glucose criterion of 7.0 mmol/l was superior to 7.8 mmol/l in screening for diabetes.

Diet and risk of coronary heart disease and type 2 diabetes

A high intake of saturated fat is an important risk factor for coronary heart disease (CHD) and type 2 diabetes. However the declining rates of CHD in many affluent societies and the steady increase in type 2 diabetes worldwide suggest that these important causes of serious morbidity and premature mortality have differing risk or protective factors worldwide. Changed macronutrient composition, reduced cigarette smoking, and improved treatment of risk factors and acute cardiac events might explain the reduction in risk of CHD, whereas the increasing rates of obesity are probably the most important explanation for the increase in diabetes. Coronary risk factors associated with diabetes could outweigh improvements in conventional cardiovascular risk factors such that the decline in CHD could be stopped or reversed unless rates of obesity can be reduced. Reduced intake of saturated fatty acids and other lifestyle interventions aimed at lowering rates of obesity are the changes most likely to reduce the epidemic numbers of people with type 2 diabetes and CHD.

Diabetes and impaired glucose tolerance in Aboriginal Australians: prevalence and risk

The prevalence and risk of having impaired glucose tolerance (IGT) and diabetes was estimated relative to body mass index (BMI) among Australian Aboriginal people. A stratified analysis was undertaken of community screening data. Measures included fasting and 2-h glucose concentrations, and BMI (five strata: <22, 22-24.9, 25-29.9, 30-34.9 and >/=35 kg/m(2)). Age was stratified into three groups: 15-34.9, 35-44.9, and >/=45 years. Participants were men and women, ages 15-94 years (n=2626). The prevalence of IGT and diabetes, respectively, adjusted for age and BMI, was 139 and 142 cases/1000 persons among men, and 157 and 152 cases/1000 persons among women. Odds ratios (95% CI) for IGT and diabetes for increasing BMI strata >/=22 kg/m(2) ranged from 1.7 (1.0 to 2.9) to 5.1 (2.4-10.5) for IGT, and from 2.0 (1.2-3.5) to 6.1 (3.3-11.1) for diabetes. For IGT and diabetes, across genders, the population attributable risk percentages (95% CI) for BMI >/=22 kg/m(2) were 34.1% (26.2-41.9%) for IGT, and 46.4% (38.5-54.5%) for diabetes. Diabetes and IGT have reached epidemic proportions among Australian Aboriginal people. An urgent need exists for programmes to reduce the prevalence of diabetes risk factors, especially BMI of 22 kg/m(2) or more, a limit lower than advocated for Euro-American populations.

Macrovascular disease risk factors and insulin resistance in Aboriginal and Torres Strait Islander people

It has been proposed that insulin resistance (IR) underlies a cluster of cardiovascular disease (CVD) risk factors constituting a "metabolic syndrome." CVD is a leading cause of premature mortality among indigenous Australians. In a group of younger (15-44 years, fasting glucose <7.8 mmol/l) Aboriginal (n=643) and Torres Strait Islander (n=220) people participating in community-based risk factor surveys, we identified high prevalences of metabolic syndrome components: glucose intolerance, dyslipidaemia, hypertension, and IR. There were inconsistent associations of IR with other risk factors, and the data do not support a direct causal relationship between insulin and other metabolic variables. Rather, metabolic syndrome components may arise from social and environmental factors interacting with behavioural and biochemical factors in individuals.

Improvements in circulating cholesterol, antioxidants, and homocysteine after dietary intervention in an Australian Aboriginal community

BACKGROUND

Poor nutrition contributes to high rates of coronary heart disease among Australian Aboriginal populations. Since late 1993, the Aboriginal community described here has operated a healthy lifestyle program aimed at reducing the risk of chronic disease.

OBJECTIVE

We evaluated the effectiveness of a community-directed intervention program to reduce coronary heart disease risk through dietary modification.

DESIGN

Intervention processes included store management policy changes, health promotion activities, and nutrition education aimed at high-risk individuals. Dietary advice was focused on decreasing saturated fat and sugar intake and increasing fruit and vegetable intake. Evaluation of the program included conducting sequential, cross-sectional risk factor surveys at 2-y intervals; measuring fasting cholesterol, lipid-soluble antioxidants, and homocysteine concentrations; and assessing smoking status. Nutrient intakes were estimated from analysis of food turnover in the single community store.

RESULTS

There was a significant reduction in the prevalence of hypercholesterolemia (age-adjusted prevalences were 31%, 21%, and 15% at baseline, 2 y, and 4 y, respectively; P < 0.001). There were significant increases in plasma concentrations of alpha-tocopherol, lutein and zeaxanthin, cryptoxanthin, and beta-carotene across the population. Retinol and lycopene concentrations did not change significantly. Mean plasma homocysteine concentrations decreased by 3 micromol/L. There was no significant change in smoking prevalence between the 2 follow-up surveys. There was an increase in the density of fresh fruit and vegetables and carotenoids in the food supply at the community store.

CONCLUSION

This community-directed dietary intervention program reduced the prevalence of coronary heart disease risk factors related to diet.