Health-related behaviours in a remote Indigenous population with Type 2 diabetes: a Central Australian primary care survey in the Telehealth Eye and Associated Medical Services Network [TEAMSnet] project

AIM

There is a wealth of data concerning the health behaviours of Indigenous Australians, but the health behaviours of Indigenous Australians with diabetes are not systematically documented. At the clinical level, understanding a person's health behaviours can help identify and address barriers to diabetes care and promote good clinical outcomes.

METHODS

We used a novel survey tool to systematically collect health behaviour data on Smoking, Nutrition, Alcohol consumption, Physical activity and Emotional well-being (SNAPE) from Indigenous Australians with Type 2 diabetes in a remote primary care setting in Alice Springs.

RESULTS

At least one of the five surveys in the SNAPE tool was completed by 210 participants: 30% male, mean age 52.6 years (range 22.9 - 87.4). Fifty per cent of men and 23% of women were current smokers (P < 0.001). None of the participants reported an adequate intake of vegetables. Only 9.6% reported an adequate fruit intake. Some 49% of men and 32% of women consumed alcohol in the past year (P = 0.022), and 46% of drinkers were considered high-risk or likely-dependent drinkers. On average, participants walked 10 min or more at a time 6.0 days a week and spent 4.8 h sitting on a weekday. Mean adapted Patient Health Questionnaire 9 score was 4.61, with 34% of participants having mild depressive symptoms and 11% having moderate-severe depressive symptoms.

CONCLUSIONS

Our SNAPE survey tool results present a high-risk, disadvantaged Indigenous population with Type 2 diabetes. More resources will be needed to sustainably implement interventions with the goal of improving health behaviours and subsequent long-term health.

Diabetes care in remote Australia: the antenatal, postpartum and inter-pregnancy period

BACKGROUND

Aboriginal and Torres Strait Islander women experience high rates of diabetes in pregnancy (DIP), contributing to health risks for mother and infant, and the intergenerational cycle of diabetes. By enhancing diabetes management during pregnancy, postpartum and the interval between pregnancies, the DIP Partnership aims to improve health outcomes and reduce risks early in the life-course. We describe a mixed methods formative study of health professional's perspectives of antenatal and post-partum diabetes screening and management, including enablers and barriers to care.

METHODS

Health professionals involved in providing diabetes care in pregnancy, from a range of health services across the Northern Territory, completed the survey (n = 82) and/or took part in interviews and/or focus groups (n = 62).

RESULTS

Qualitative findings highlighted factors influencing the delivery of care as reported by health professionals, including: whose responsibility it is, access to care, the baby is the focus and pre-conception care. The main challenges were related to: disjointed systems and confusion around whose role it is to provide follow-up care beyond six weeks post-partum. Quantitative findings indicated that the majority of health professionals reported confidence in their own skills to manage women in the antenatal period (62%, 40/79) and slightly lower rates of confidence in the postpartum interval (57%, 33/58).

CONCLUSION

These findings regarding whose role it is to provide postpartum care, along with opportunities to improve communication pathways and follow up care have informed the design of a complex health intervention to improve health systems and the provision of DIP related care.

Cross-sectional associations of albuminuria among Aboriginal and Torres Strait Islander adults: the eGFR Study

OBJECTIVE

To describe the detailed associations of albuminuria among a contemporary cohort of Aboriginal and Torres Strait Islander people to inform strategies for chronic kidney disease prevention and management.

METHODS

A cross-sectional analysis of Indigenous participants of the eGFR Study.

MEASURES

Clinical, biochemical and anthropometric measures were collected (including body-circumferences, blood pressure (BP); triglycerides, HbA1c, liver function tests, creatinine; urine- microscopic-haem, albumin: creatinine ratio (ACR), prescriptions- angiotensin converting enzyme inhibitor or angiotensin receptor II antagonist (ACEI/ARB). Albuminuria and diabetes were defined by an ACR>3.0 mg/mmol, and HbA1c≥48 mmol/mol or prior history respectively. Waist: hip ratio (WHR), and estimated glomerular filtration rate (eGFR) were calculated. ACR was non-normally distributed; a logarithmic transformation was applied (in base 2), with each unit increase in log2-albuminuria representing a doubling of ACR.

RESULTS

591 participants were assessed (71% Aboriginal, 61.6% female, mean age 45.1 years, BMI 30.2 kg/m² , WHR 0.94, eGFR 99.2 ml/min/1.73m² ). The overall prevalence of albuminuria, diabetes, microscopic-haem and ACEI/ARB use was 41.5%, 41.5%, 17.8% and 34.7% respectively; 69.3% of adults with albuminuria and diabetes received an ACEI/ARB. Using multivariable linear regression modelling, the potentially modifiable factors independently associated with log2-albuminuria were microscopic-haem, diabetes, WHR, systolic BP, alkaline phosphatase (all positive) and eGFR (inverse).

CONCLUSION

Albuminuria is associated with diabetes, central obesity and haematuria. High ACEI/ARB prescribing for adults with diabetes and albuminuria was observed. Further understanding of the links between fat deposition, haematuria and albuminuria is required.

Bilirubin concentration is positively associated with haemoglobin concentration and inversely associated with albumin to creatinine ratio among Indigenous Australians: eGFR Study

Low serum bilirubin concentrations are reported to be strongly associated with cardio-metabolic disease, but this relationship has not been reported among Indigenous Australian people who are known to be at high risk for diabetes and chronic kidney disease (CKD).

HYPOTHESIS

serum bilirubin will be negatively associated with markers of chronic disease, including CKD and anaemia among Indigenous Australians.

METHOD

A cross-sectional analysis of 594 adult Aboriginal and Torres Strait Islander (TSI) people in good health or with diabetes and markers of CKD. Measures included urine albumin: creatinine ratio (ACR), estimated glomerular filtration rate (eGFR), haemoglobin (Hb) and glycated haemoglobin (HbA1c). Diabetes was defined by medical history, medications or HbA1c≥6.5% or ≥48mmol/mol. Anaemia was defined as Hb<130g/L or <120g/L in males and females respectively. A multivariate regression analysis examining factors independently associated with log-bilirubin was performed.

RESULTS

Participants mean (SD) age was 45.1 (14.5) years, and included 62.5% females, 71.7% Aboriginal, 41.1% with diabetes, 16.7% with anaemia, 41% with ACR>3mg/mmol and 18.2% with eGFR<60mL/min/1.73m². Median bilirubin concentration was lower in females than males (6 v 8μmol/L, p<0.001) and in Aboriginal than TSI participants (6 v 9.5μmol/L, p<0.001). Six factors explained 35% of the variance of log-bilirubin; Hb and cholesterol (both positively related) and ACR, triglycerides, Aboriginal ethnicity and female gender (all inversely related).

CONCLUSION

Serum bilirubin concentrations were positively associated with Hb and total cholesterol, and inversely associated with ACR. Further research to determine reasons explaining lower bilirubin concentrations among Aboriginal compared with TSI participants are needed.

Associations of mortality and cardiovascular disease risks with diabetes and albuminuria in urban Indigenous Australians: the DRUID follow-up study

AIM

To assess the relationships of diabetes and albuminuria with all-cause mortality and cardiovascular disease outcomes in a population without prior cardiovascular disease using data from the Darwin Region Urban Indigenous Diabetes (DRUID) study.

METHODS

We conducted a prospective cohort study of 706 participants (aged 15-81 years, 68% women) without prior cardiovascular disease who underwent a 75-g oral glucose tolerance test. Deaths and fatal or non-fatal cardiovascular disease were determined over 7 years, and hazard ratios with 95% CIs and population attributable risks were estimated for baseline glycaemia and albuminuria.

RESULTS

Compared with normoglycaemia and after adjustment for age, sex, hypertension, dyslipidaemia and smoking, known diabetes was associated with an adjusted hazard ratio of 4.8 (95% CI 1.5-14.7) for all-cause mortality and 5.6 (95% CI 2.1-15.2) for cardiovascular disease. Compared with normoalbuminuria, the respective adjusted risks for macroalbuminuria were 10.9 (95% CI 3.7-32.1) and 3.9 (95% CI 1.4-10.8). The Adjusted all-cause mortality and cardiovascular disease estimated population attributable risks for diabetes were 27% and 32%, and for albuminuria they were 32% and 21%, respectively.

CONCLUSIONS

In our study population, the burden of mortality and cardiovascular disease was largely driven by diabetes and albuminuria. This finding on the influence of diabetes and albuminuria is consistent with reports in other high-risk Indigenous populations and should be better reflected in risk scores and intervention programmes.

Use of the Bayer DCA 2000+ for the measurement of glycated haemoglobin in a remote Australian Aboriginal community

Background: Good glycaemic control in type 2 diabetes can reduce both morbidity and mortality, and monitoring of glycated haemoglobin A1c (HbA1c) is currently recommended for this purpose.

Methods: Haemoglobin A1c can be measured using the portable Bayer DCA 2000+. As part of a community-based screening project for chronic diseases, subjects with impaired fasting glucose concentrations or diabetes had their HbA1c concentration measured on the analyser. HbA1c measurements were also made in a laboratory using cation-exchange high-performance liquid chromatography. Results were then compared to those obtained in the field. HbA1c values were loge transformed to obtain a normal distribution.

Results: Mean (95% confidence interval) HbA1c measured on the DCA 2000+ ( n = 39) was 6.3% (5.8, 6.9%), while that measured in the laboratory was 6.5% (6.0, 7.0%). The correlation coefficient ( r) between the measurements was 0.96 ( P < 0.01). Bland-Altman analysis revealed that the DCA 2000+ estimate of HbA1c could be used interchangeably with that from the laboratory (mean bias = 0.1%, limits of agreement - 1.1, 0.8%). The sensitivity, specificity and positive predictive value of the DCA 2000+ estimate of HbA1c using a cut-off value of <7% for adequate glycaemic control, were all 100%.

Conclusions: The DCA 2000+ may be used to measure HbA1c in remote communities.

Periodontal therapy and glycaemic control among individuals with type 2 diabetes: reflections from the PerioCardio study

OBJECTIVES

Diabetes mellitus and periodontal disease are highly prevalent among Indigenous Australian adults. Untreated periodontitis impacts glycaemic control in people with diabetes. The aim of this study was to report on the effect of periodontal therapy on glycaemic control among people with obesity.

METHODS

This subgroup analysis is limited to 62 participants with diabetes from the original 273 Aboriginal Australian adults enrolled into the PerioCardio study. Intervention participants received full-mouth non-surgical periodontal scaling during a single, untimed session while controls were untreated. Endpoints of interest included change in glycated haemoglobin (HbA1c), C-reactive protein (CRP) and periodontal status at 3 months post-intervention.

RESULTS

There were more females randomized to the treatment group (n = 17) than control (n = 10) while the control group had a higher overall body mass index (BMI) [mean (SD)] 33.1 (9.7 kg m^-2 ) versus 29.9 (6.0 kg m^-2 ). A greater proportion of males were followed up at 3 months compared to females, P = 0.05. Periodontal therapy did not significantly reduce HbA1c: ancova difference in means 0.22 mmol mol^-1 (95% CI -6.25 to 6.69), CRP: ancova difference in means 0.64 (95% CI -1.08, 2.37) or periodontal status at 3 months.

CONCLUSIONS

Non-surgical periodontal therapy did not significantly reduce glycated haemoglobin in participants with type 2 diabetes. Reasons are likely to be multifactorial and may be influenced by persistent periodontal inflammation at the follow-up appointments. Alternatively, the BMI of study participants may impact glycaemic control via alternative mechanisms involving the interplay between inflammation and adiposity meaning HbA1c may not be amenable to periodontal therapy in these individuals.

Nutritional predictors of chronic disease in a Central Australian Aboriginal cohort: A multi-mixture modelling analysis

BACKGROUND AND AIMS

Chronic diseases (including diabetes, cardiovascular disease, hypertension and chronic kidney disease) are major contributors to the total burden of disease for Aboriginal people. Here we used novel epidemiological modelling to investigate nutritional profiles at a population level associated with chronic disease.

METHODS AND RESULTS

Multi-mixture modelling, was used to group members of a Central Australian Aboriginal population (n = 444) based on their nutritional profile from a risk factor prevalence survey in 1995. Multi-mixture modelling assigned % membership to four classes; Class 1 (young, low adiposity and lipids, low dietary antioxidants; n = 171.7); Class 2 (older, greater adiposity and lipids; n = 22.6); Class 3 (predominantly female, greater adiposity and antioxidants, low smoking; n = 134.3) and Class 4 (predominantly male, greater lipids and adiposity, low antioxidants, high smoking prevalence; n = 115.4). For persons free of chronic disease (n = 285), incident chronic disease for classes 1, 3 and 4 was determined using follow up hospital, primary health care and death records collected in 2004/05. Fifty-four percent of Class 4 had incident chronic disease, an excess of 3355 events per 100,000 person years relative to Class 1. Incident CVD, hypertension, or CKD was highest for Class 4 and incident diabetes highest for Class 3.

CONCLUSION

Multi-mixture modelling appears useful in identifying population subgroups of an Aboriginal population at risk of chronic conditions.

Associations of serum adiponectin with markers of cardio-metabolic disease risk in Indigenous Australian adults with good health, diabetes and chronic kidney disease

The higher serum adiponectin concentrations observed in females are often attributed to differences in adiposity or sex hormones. There is little data describing adiponectin in Indigenous Australians, and no studies examining its association with cardio-metabolic disease risk markers and chronic kidney disease (CKD).

AIM

To describe the relationship of serum adiponectin with cardio-metabolic disease risk markers and kidney function in a community-based sample of Indigenous Australian adults, with particular reference to sex-specific differences.

METHODS

A cross-sectional analysis of a community-based volunteer sample of 548 Indigenous Australian adults (62% female), stratified into five cardio-metabolic risk groups ranging from good health (strata-1) to high cardio-metabolic risk and low measured glomerular filtration rate (mGFR, <60ml/min/1.73m²) (strata-5). We examined serum adiponectin concentrations with cardio-metabolic risk markers, albuminuria and mGFR.

RESULTS

Indigenous Australian females had a lower than expected adiponectin concentration (3.5μg/ml), which was higher than males in strata 1-4 (as in other populations), but not in strata-5 (mGFR<60, p=0.19), and higher leptin: adiponectin ratio than other populations (7.8ng/μg - strata-1, healthy females; 12.2ng/μg - strata-3, females with diabetes and mGFR≥90). Female-gender, HDL-cholesterol (positive), mGFR and waist: hip ratio (WHR) (inverse) were independently associated with log-adiponectin when mGFR≥60; when mGFR<60, female-gender was associated with 0.27 units lower log-adiponectin.

CONCLUSION

Female-gender was not associated with higher adiponectin concentrations in Indigenous Australians with mGFR<60ml/min/1.73m². High WHR was frequent in both genders, and inversely associated with adiponectin. Longitudinal studies are needed to examine relationships of serum adiponectin, obesity and cardiovascular disease events in Indigenous Australians.

Performance of formulas for estimating glomerular filtration rate in Indigenous Australians with and without Type 2 diabetes: the eGFR Study

AIMS

It has been proposed that the Chronic Kidney Disease Epidemiology Collaboration formula estimates glomerular filtration rate more accurately than the Modification of Diet in Renal Disease formula. With the very high incidence of diabetes and end-stage kidney disease in Indigenous Australians, accurate estimation of glomerular filtration rate is vital in early detection of kidney disease. We aimed to assess the performance of the Chronic Kidney Disease Epidemiology Collaboration, Modification of Diet in Renal Disease and Cockcroft-Gault formulas in Indigenous Australians with and without diabetes.

METHODS

Indigenous Australians with (n = 224) or without (n = 340) Type 2 diabetes had a reference glomerular filtration rate measure using plasma disappearance of iohexol (measured glomerular filtration rate) over 4 h. Serum creatinine was measured by an enzymatic method. Performance was assessed by bias (measured glomerular filtration rate - estimated glomerular filtration rate) and accuracy (percentage of estimated glomerular filtration rate within 30% of measured glomerular filtration rate).

RESULTS

The median measured glomerular filtration rate (interquartile range) in participants with or without diabetes was 97 (68-119) and 108 (90-122) ml min(-1)  1.73 m(-2) , respectively. The Chronic Kidney Disease Epidemiology Collaboration formula had smaller bias and greater accuracy than the Modification of Diet in Renal Disease and Cockcroft-Gault formulas overall, for participants both with and without diabetes. However, for estimated glomerular filtration rate > 90 ml min(-1)  1.73 m(-2) , the Chronic Kidney Disease Epidemiology Collaboration formula had greater bias in participants with diabetes, underestimating measured glomerular filtration rate by 7.4 vs. 1.0 ml min(-1)  1.73 m(-2) in those without diabetes. The Chronic Kidney Disease Epidemiology Collaboration formula was less accurate across the whole range of estimated glomerular filtration rates in participants with vs. those without diabetes (87.1% vs. 93.3%).

CONCLUSIONS

The Chronic Kidney Disease Epidemiology Collaboration formula outperforms the Modification of Diet in Renal Disease and Cockcroft-Gault formulas overall in Indigenous Australians with and without diabetes. However, the Chronic Kidney Disease Epidemiology Collaboration formula has greater bias in people with diabetes compared with those without diabetes, especially in those with normal renal function.

Dietary patterns as predictors of successful ageing

OBJECTIVES

To examine associations between dietary patterns identified by factor analysis, and successful ageing.

DESIGN

Prospective cohort study with diet measured in 1990-4, and successful ageing in 2003-7. Ordered logistic regression with outcome determined as dead/usual ageing/successful ageing was used to examine associations with quintile groups of dietary factor scores.

PARTICIPANTS

Men and women (n=6308), without history of major illness at baseline, and aged >70 years at follow-up, or who had died before follow-up but would have been aged >70 at the commencement of follow-up, from the Melbourne Collaborative Cohort Study.

MEASUREMENTS

Frequencies of intake of 121 foods at baseline were collected in a food frequency questionnaire. Anthropometry and other health and lifestyle data were collected. At follow-up, questionnaire data relating to mental health, physical function and medical history were used to define successful ageing.

RESULTS

Four dietary factors were identified, characterized by higher loadings for (1) vegetables; (2) fruit, (3) feta, legumes, salad, olive oil, and inverse loadings for tea, margarine, cake, sweet biscuits and puddings; (4) meat, white bread, savoury pastry dishes and fried foods. In models excluding body size, the second factor 'Fruit' was positively associated with successful ageing (OR in top 20% vs lowest 20% of score 1.31, 95%CI (1.05-1.63), p trend across quintile groups 0.001); while the fourth factor 'Meat/fatty foods' was inversely associated (OR in top 20% vs lowest 20% of score 0.69, 95%CI (0.55-0.86), p trend across quintile groups 0.001). Factors 1 and 3 did not show significant associations with successful ageing. The association for 'Fruit' was little altered after adjustment for body size, while for 'Meat/fatty foods' the association was somewhat attenuated.

CONCLUSION

A dietary pattern including plenty of fruit while limiting meat and fried foods may improve the likelihood of ageing successfully.

Oral health behaviours and perceptions reported by Indigenous Australians living in Darwin, Northern Territory

OBJECTIVE

To describe the reported oral health behaviours and perceptions of Indigenous Australians living in Darwin, Northern Territory and to compare those with estimates for Darwin and Australia derived from the National Survey of Adult Oral Health (NSAOH).

PARTICIPANTS

A total of 181 Indigenous Australians aged 22 years and over living in Darwin, participating in screening for a wider randomised clinical trial, were included.

METHOD

Information on socio-demographic characteristics, oral health status including oral health behaviours and perceptions was collected using a questionnaire. Differences between the Darwin study (DS) participants and Australians in NSAOH were made based on non-overlapping 95% confidence intervals.

RESULTS

Almost 72% of DS participants had last seen a dentist over a year earlier, compared to 47% and 39% of NSAOH Darwin and Australian participants, respectively. A higher proportion of DS participants usually visited a dentist because of a problem than NSAOH Darwin and NSAOH Australian participants. A higher proportion of DS participants had avoided or delayed a dental visit because of cost than NSAOH participants. Over three times as many DS participants rated their oral health as fair/poor compared to NSAOH participants. A higher proportion of DS participants had perceived gum disease and one or more symptoms of gum disease than NSAOH participants. A higher proportion of DS participants experienced toothache, felt uncomfortable about appearance of their mouth and avoided eating because of oral problems than NSAOH participants.

CONCLUSIONS

A higher proportion of Indigenous Australians living in Darwin presented with non-optimal oral health behaviours and perceptions compared with both the Darwin and Australian general populations.

Hypertriglyceridemic waist and newly-diagnosed diabetes among remote-dwelling Indigenous Australians

AIMS

Hypertriglyceridemic waist (HTgW) is predictive of cardiovascular disease. The HTgW relationship with diabetes is little studied.

METHODS

This study analysed data from diabetes and cardiovascular risk factor screening programmes in remote Indigenous Australian settlements. Elevated waist girth (EW) was defined as ≥90 cm for men (n = 1134) or ≥80 cm for women (n = 1313). Hypertriglyceridemia (ETg) was defined as ≥1.7 mmol/L. Diabetes was defined as fasting plasma glucose ≥7.0 mmol/L. Body mass index (BMI) was categorised as <22, 22-24.9 and >25.0 kg/m(2). Logistic regression was used to analyse the odds of newly-diagnosed diabetes for individuals with either HTgW, ETg or EW, relative to individuals with values below cut-offs.

RESULTS

The prevalence of HTgW was 33.2% for men and 34.8% for women. Accounting for age-group and gender, newly-diagnosed diabetes was associated (odds ratio (OR) (95% confidence interval)) with HTgW: 9.6 (6.6, 13.8). The relationship remained strong after accounting for the covariates BMI and smoking (OR = 4.9 (2.7, 8.8)). In BMI-stratified analyses the strongest odds were observed for the lowest category (<22 kg/m(2): OR = 12.9 (4.0, 41.7)).

CONCLUSIONS

HTgW has a high prevalence and is associated with newly-diagnosed diabetes in Indigenous people, particularly those with BMI <22 kg/m(2), whom clinicians might not normally consider for screening.

Plasma retinol: a novel marker for cardiovascular disease mortality in Australian adults

BACKGROUND AND AIMS

Vitamin A affects inflammation and immune function and is thus a factor of interest in relation to cardiovascular disease (CVD). As vitamin A circulates in the plasma in the form of retinol, this study aims to describe the relationship between plasma retinol and the 5-year incidence of CVD mortality.

METHODS AND RESULTS

Community-dwelling adults (n = 441, 45% with type 2 diabetes) were recruited in Melbourne, assessed at baseline and followed for 5 years. At baseline, CVD risk factors were assessed by clinical evaluation, by personal lifestyle questionnaire and from biochemistry (plasma fasting glucose, lipids, total homocysteine, C-reactive protein, retinol and carotenoids plus the urinary albumin excretion rate over 24 h.). Dietary intake was assessed by a validated food frequency questionnaire. CVD mortality over 5-years was determined by consulting state or national registries. The majority of participants had adequate plasma retinol concentrations (≥30 μg/dL). The final Cox regression model indicated that those in the highest tertile of plasma retinol (mean ± SD) 76 ± 14 μg/dL) had a significantly lower risk of 5-year CVD mortality (hazard ratio 0.27 [95% confidence interval 0.11, 0.68], P = 0.005), an effect that was not readily explained in terms of traditional CVD risk factors or dietary intake.

CONCLUSION

In well-nourished older Australian adults, plasma retinol was inversely associated with CVD mortality via mechanisms apparently unrelated to established CVD risk factors and dietary intake.

Obesity: lessons from evolution and the environment

The 9th Stock Conference acknowledged the complex background of genetic, cultural, environmental and evolutionary factors of obesity. Gene-environment interactions underlie the flexibility in body-weight and body-fat regulation, illustrated by the hunter-gatherers' feast and famine lifestyle, the variation in physical activity over the lifespan being highest at reproductive age, the variation in energy intake through 'eating in the absence of hunger', while running the risk of exceeding the capacity of triacylglyceride storage, leading to lipotoxicity and metabolic problems. Perinatal metabolic programming for obesity via epigenetic changes in response to a 'Western diet' results in production of lipid-poor milk and metabolically efficient pups, contributing to the perpetuation of obesity throughout generations. Evolutionary insight from comparative physiology and ecology indicates that over generations activity-induced energy expenditure has remained the same compared to wild mammals, that energy balance might be dependant on protein balance, while the function of taste changed from detection of poison or energy to social drinking and social behaviour. At present, the impact of assortative mating on obesity prevalence is unambiguously positive. The complexity that appeared can only be fully appreciated by setting the data into the context of our evolutionary history.

Increased bone mineral density in Aboriginal and Torres Strait Islander Australians: impact of body composition differences

Bone mineral density (BMD) has been reported to be both higher and lower in Indigenous women from different populations. Body composition data have been reported for Indigenous Australians, but there are few published BMD data in this population. We assessed BMD in 161 Indigenous Australians, identified as Aboriginal (n=70), Torres Strait Islander (n=68) or both (n=23). BMD measurements were made on Norland-XR46 (n=107) and Hologic (n=90) dual-energy X-ray absorptiometry (DXA) machines. Norland BMD and body composition measurements in these individuals, and also in 36 Caucasian Australians, were converted to equivalent Hologic BMD (BMD(H)) and body composition measurements for comparison. Femoral neck (FN) and lumbar spine Z-scores were high in Indigenous participants (mean FN Z-score: Indigenous men +0.98, p<0.0001 vs. mean zero; Indigenous women +0.82, p<0.0001 vs. mean zero). FN BMD(H) was higher in Aboriginal and/or Torres Strait Islander than Caucasian participants, after adjusting for age, gender, diabetes and height and remained higher in men after addition of lean mass to the model. We conclude that FN BMD is higher in Aboriginal and/or Torres Strait Islander Australians than Caucasian Australian reference ranges and these differences still remained significant in men after adjustment for lean mass. It remains to be seen whether these BMD differences translate to differences in fracture rates.

Can the Mediterranean diet lower HbA1c in type 2 diabetes? Results from a randomized cross-over study

BACKGROUND AND AIMS

To investigate the impact of a diet modeled on the traditional Cretan Mediterranean diet on metabolic control and vascular risk in type 2 diabetes.

METHODS AND RESULTS

Twenty-seven subjects (47-77 yrs) with type 2 diabetes were randomly assigned to consume either the intervention diet ad libitum or their usual diet for 12 weeks and then cross over to the alternate diet. Most of the meals and staple foods for the intervention diet were provided. Lipids, glycemic variables, blood pressure, homocysteine, C-reactive protein, plasma carotenoids and body composition (anthropometry and dual energy X-ray absorptiometry) were assessed at baseline, and at the end of both diet periods. Dietary adherence was monitored using plasma carotenoid and fatty acid (FA) analysis, complemented by diet diaries. Compared with usual diet, on the ad libitum Mediterranean intervention diet glycosylated haemoglobin fell from 7.1% (95% CI: 6.5-7.7) to 6.8% (95% CI: 6.3-7.3) (p=0.012) and diet quality improved significantly [plant:animal (g/day) food ratio increased from 1.3 (95% CI: 1.1-1.5) to 5.4 (95% CI: 4.3-6.6) (p<0.001)], plasma lycopene and lutein/zeaxanthin increased (36% and 25%, respectively), plasma saturated and trans FAs decreased, and monounsaturated FAs increased.

CONCLUSION

A traditional moderate-fat Mediterranean diet improves glycemic control and diet quality in men and women with well-controlled type 2 diabetes, without adverse effects on weight.

Does a Mediterranean diet reduce the mortality risk associated with diabetes: evidence from the Melbourne Collaborative Cohort Study

BACKGROUND AND AIMS

Diabetes is a risk factor for cardiovascular disease (CVD), yet southern European migrants to Australia with high rates of type 2 diabetes have relatively low CVD mortality. Our aim was to determine whether a Mediterranean style diet could reduce mortality in people with diabetes.

METHODS AND RESULTS

Participants included 16,610 males and 23,860 females from the Melbourne Collaborative Cohort Study; 25% were born in Greece or Italy, and 2150 had previously been diagnosed with diabetes or had elevated blood glucose at baseline (1990-94). Data on demographic, behavioral and physical risk factors were also collected. A personal Mediterranean Diet Score (MDS) was calculated using data from a validated 121-item food frequency questionnaire. Total and CVD mortality data were available up to 2003. Diabetes (new and known) at baseline, was associated with total mortality (men HR 1.43, 95%CI 1.26-1.62; women HR 1.86 95%CI 1.58-2.18), and CVD mortality (men HR 1.53, 95%CI 1.21-1.94; women HR 2.10 95%CI 1.48-2.97) in multivariate models. There was no evidence that glucose tolerance modified the associations between MDS and total or CVD mortality (p interaction all > 0.16). The HRs for total mortality per unit of MDS were 0.96 (95% CI 0.93-0.99) in men and 0.94 (95% CI 0.92-0.97) in women. The HRs for CVD mortality per unit of MDS were 0.94 (95% CI 0.89-0.99) in men and 0.94 (95% CI 0.87-1.01) in women.

CONCLUSION

Our results add to the evidence supporting the benefit of a Mediterranean style diet for people with type 2 diabetes.

NMR-determined lipoprotein subclass profile is associated with dietary composition and body size

BACKGROUND AND AIMS

Dyslipidemia is influenced by diet and body habitus. The Nuclear Magnetic Resonance spectroscopy lipoprotein subclass profile (NMR-LSP) is associated with diabetes and its vascular complications; and an NMR-LSP featuring large VLDL particles and small LDL and HDL particles is linked with cardiovascular disease (CVD). Thus interventions which favourably modify NMR-LSP may reduce risk for diabetes, its complications and CVD. The study aim was to investigate the associations between NMR-LSP, dietary composition and body size measures using data from the Melbourne Collaborative Cohort Study (MCCS).

METHODS AND RESULTS

NMR-LSP was assessed in 313 men and 403 women (median age 54 years) randomly selected from a community-based cohort study. Diet was assessed using a specifically developed food frequency questionnaire (FFQ), and body size was assessed by body mass index (BMI) or waist:hips ratio (WHR). To simplify the 15 NMR-LSP variables, factor analysis was used to derive a single factor. Multivariate linear regression with this factor score as the dependent variable demonstrated that in men, total PUFA and n-6 dietary fat intake and BMI were associated with a more atherogenic NMR-LSP pattern; while in women dietary glycemic index and WHR demonstrated positive associations, and n-3 fat intake an inverse association.

CONCLUSIONS

We developed a single factor score to summarize the NMR-LSP that has the benefit of combining all aspects of the NMR-LSP and accounting for correlations between them. We have shown correlations between the NMR-LSP and body size and dietary composition.

Is risk of diabetic retinopathy lower in Australia's Greek-born migrants?

AIM

The standardized cardiovascular disease death rate for the Greek population in Crete has increased since the 1960s, unlike the all-cause and cardiovascular disease death rate for Australia's Greek migrant population, which has remained paradoxically low. A small window of opportunity remains in which the vascular profile of this interesting atypical migrant population can be characterized. This study assessed whether ethnicity modulates the risk of diabetic retinopathy in Greek-born migrants to Australia.

METHODS

The study design was a community-based cross-sectional study of diabetic retinopathy in 107 Greek-born and Australian-born men with Type 2 diabetes, aged 44-83 years. Diabetic retinopathy was assessed by mydriatic three-field retinal photography.

RESULTS

Prevalence of diabetic retinopathy was lower in Greek-born than in Australian-born participants (22 and 37%, respectively). Despite having a higher mean systolic blood pressure level (148 vs. 137 mmHg), Greek-born men had a significantly lower risk of diabetic retinopathy than Australian-born men, after adjusting for age, duration of diabetes, glycated haemoglobin, systolic blood pressure, diastolic blood pressure, albumin to creatinine ratio, and total cholesterol and triglyceride levels [odds ratio 0.32 (0.10-0.99); r(2) = 0.41, P = 0.047].

CONCLUSION

Greek ethnicity may confer some protection against diabetic retinopathy to Australia's Greek-born migrants, an effect not explained by established risk factors for diabetic retinopathy. A small window of opportunity remains in which to elucidate the ethnicity-related exposures that modulate vascular risk in this older migrant population.

Diet and exercise in the prevention of diabetes

BACKGROUND

Individuals with impaired fasting glucose or impaired glucose tolerance are at high risk of progression to type 2 diabetes. Lifestyle modification through change to diet and exercise habit has considerable potential to prevent or delay the onset of this disease.

METHODS

A systematic literature search was undertaken of Medline, EMBASE, the Cochrane library and the Cumulative Index to Nursing and Allied Health Literature for journal articles relevant to the question of whether type 2 diabetes can be prevented by lifestyle change.

RESULTS

Four cohort studies in a total of 4864 high risk individuals followed for a period of 2.5-6 years were identified. These showed that lifestyle change may reduce the incidence of type 2 diabetes by 28-59%. Moreover, follow-up studies also indicate that diabetes incidence rates continue to be depressed many years after the discontinuation of a lifestyle intervention. Evidence from a meta-analysis confirms this evidence and suggests that it would be necessary to treat 6.4 (95% confidence interval 5.0-8.4) individuals to prevent or delay one case of diabetes through lifestyle intervention. An examination of weight loss diets (low fat, high protein or Mediterranean) suggests each may be effective but each has limitations requiring care in food selection. Evidence also suggests that the maintenance of weight loss also requires regular exercise with an additional expenditure of approximately 8.4 MJ week(-1) (2000 kcal week(-1)).

CONCLUSIONS

Diabetes can be prevented by lifestyle change. The challenge is to develop public health approaches to support individuals with respect to incorporating the lifestyle changes needed to reduce the risk of diabetes into their everyday life.

Plasminogen activator inhibitor-1 (PAI-1) activity and retinal vascular calibre in type 2 diabetes

OBJECTIVE

To describe relationships of retinal vascular calibre with plasminogen activator inhibitor-1 (PAI-1) and other cardiovascular risk factors in people with type 2 diabetes.

METHODS

We recruited 112 community-based persons aged 44-83years with type 2 diabetes, photo-documented retinal status using a digital fundus camera, and measured traditional and novel vascular risk factors. Retinal arteriolar and venular calibre and the arterio-venous ratio (AVR) were determined from fundus photographs using a validated computer-assisted method.

RESULTS

In adjusted linear regression models, PAI-1 activity was strongly associated with all measures of retinal vascular calibre: positively with arterioles (p=0.005) and AVR (p=0.001), and inversely with venules (p=0.001). In addition, wider arterioles were independently associated with waist-hip ratio (p<0.0001), HDL-C (p=0.015), and lower systolic blood pressure (p=0.042), whereas narrower venules were associated with older age and a higher albumin excretion rate. Neither arteriolar nor venular calibre was associated with plasma total homocysteine or C-reactive protein concentration.

CONCLUSION

Retinal vascular calibre is independently associated with PAI-1 activity in type 2 diabetes. This finding supports a role for PAI-1 activity in the microvasculature of persons with type 2 diabetes and may explain the link between retinal vascular calibre and cardiovascular disease.

Risk factors for cardiovascular disease do not fully explain differences in carotid intima-media thickness between Indigenous and European Australians without diabetes

OBJECTIVE

To investigate whether cardiovascular risk factors can explain the higher carotid intima-media thickness (CIMT) in Indigenous compared with European Australians.

DESIGN

Cross-sectional study in three subgroups.

PATIENTS

Non-diabetic urban European (n = 86), urban Indigenous (n = 69), and remote Indigenous (n = 60) Australians aged 25-64 years.

MEASUREMENTS

CIMT, age, sex, anthropometry, blood pressure, smoking status, fasting glucose and insulin, haemoglobin (Hb)A1c, homocysteine, C-reactive protein (CRP), lipids, urinary albumin and creatinine.

RESULTS

CIMT and levels of risk factors, except fasting glucose and total cholesterol, worsened across the three groups. Log(n) fasting insulin [beta = 0.022, 95% confidence interval (CI) 0-0.0439], age (beta = 0.006, 95% CI 0.004-0.007), gender (female beta = -0.005 vs. male, 95% CI -0.084 to -0.026), mean arterial pressure (MAP) (beta = 0.001, 95% CI 0.001-0.002) and ethnicity/location [urban Indigenous (beta = 0.027, 95% CI -0.010 to 0.064 vs. European); remote Indigenous (beta = 0.083, 95% CI 0.042-0.123 vs. European)] explained 41% of variance in CIMT. Significant interactions were seen for ethnicity/location with age (P = 0.014) and MAP (P = 0.018). Age was consistently associated with CIMT across the three populations, and was associated with larger increments in CIMT for the Indigenous subgroups (beta = 0.007, 95% CI 0.005-0.009 urban; beta = 0.007, 95% CI 0.004-0.010 remote) compared with Europeans (beta = 0.003, 95% CI 0.002-0.006) in models including age, sex and MAP. MAP was only associated with CIMT in the remote Indigenous subgroup.

CONCLUSION

After adjusting for selected risk factors, CIMT in remote Indigenous participants was still higher than in Europeans. The slope of the association between age and CIMT steepened from urban Europeans to remote Indigenous.

Is there a role for monounsaturated fat in the dietary management of obesity?

Animal and human studies indicate that high saturated fat (SFA) diets can be obesogenic. Monounsaturated fat (MUFA) has acute (meal related) effects that influence energy metabolism. These include increased postprandial fat oxidation and greater diet induced thermogenesis, factors that attenuate weight gain. Chronic (diet related) studies for 12 weeks or more, demonstrate that people following high MUFA diets do not gain excessive weight even when eating ad libitum. In fact, we have observed greater body weight and fat loss in men following an ad libitum MUFA diet, when compared to a SFA diet. High MUFA diets designed for weight loss should also incorporate a high vegetable intake according to traditional Mediterranean patterns. Such diets will promote the utilisation of fat and also have a low energy density. In our experience these diets are well accepted, and offer the prospect of greater long-term adherence to dietary advice.

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.

Increased carotid intima-media thickness in remote and urban Indigenous Australians: impact of diabetes and components of the metabolic syndrome

OBJECTIVE

Indigenous Australians have rates of cardiovascular (CVD) mortality some seven to 10-fold higher than non-Indigenous Australians aged 25-64 years. We aimed to evaluate the impact of type 2 diabetes and components of the metabolic syndrome on carotid intima-media thickness (CIMT) as a marker of cardiovascular risk in Indigenous Australians living in remote and urban environments and in Australians of European ancestry.

DESIGN, PATIENTS AND MEASUREMENTS

CIMT was measured by high-resolution B-mode ultrasound imaging of the common carotid artery in 119 remote Indigenous, 144 urban Indigenous and 122 urban European Australians with and without diabetes.

RESULTS

In nondiabetic participants, CIMT was lowest in Europeans (mean (SD) 0.64 mm (0.10)), higher in urban Indigenous Australians (0.67 mm (0.12)) and highest in remote Indigenous Australians (0.73 mm (0.15), P < 0.001). CIMT was higher with diabetes with the same pattern observed between populations: 0.73 mm, 0.79 mm and 0.82 mm, respectively (P < 0.001). Traditional risk factors (age, male gender, blood pressure and HbA1c) explained 35-45% of the variance of CIMT within each population group. However, differences in CIMT between population groups were maintained after adjustment for these cardiovascular risks plus cholesterol and smoking (P < 0.001). Factor analysis revealed that variables of the metabolic syndrome, together with smoking and elevated C-reactive protein (CRP) and urinary albumin-creatinine ratio (ACR), are likely to explain the higher CIMT in Indigenous Australians (and the urban-remote gradient). Unmeasured variables (genetic, psychosocial and socioeconomic) may also contribute to higher CIMT in these populations.

CONCLUSION

Glycaemic control and metabolic syndrome components contribute significantly to premature atherogenesis in Indigenous Australians and we recommend that therapy should be targeted accordingly.

Educating to improve population health outcomes in chronic disease: an innovative workforce initiative across remote, rural and Indigenous communities in northern Australia

INTRODUCTION

Like Indigenous populations in other countries, an epidemic of chronic disease has swept across Australia's Indigenous communities in the past decade. The Northern Territory and Queensland health departments initiated preventable chronic disease strategies in 1999 and 2001, respectively. Yet finding innovative ways to translate this to the health workforce was challenging. Through support from the Australian Government, three universities, two health departments and two Indigenous organisations worked in partnership to improve workforce capacity in remote and rural communities through innovative education.

METHODS

The methods included: (i) a training needs analysis consisting of 76 semi-structured interviews with key informants, and 35 surveys of remote staff; (ii) a literature and resource review; (iii) the development of a curriculum framework using: the existing competencies and standards across the health disciplines; the identified workforce needs; and what the workforce can impact upon; (iv) a multidisciplinary workshop with 35 educators across northern Australia that resulted in the basis for agreement of the final curriculum content and framework; (v) the development of a chronic disease self-assessment tool that was piloted with remote health staff; (vi) an assisted integration process for key stakeholders. An evaluation framework was also developed, as a separate project, in conjunction with the project partners during this time.

RESULTS

This project identified that a paradigm shift is required in the way in which we educate the entire health workforce to deal effectively with the impact of chronic disease across remote, rural and Indigenous populations. In particular a need was found to educate the educators in the chronic care model and in using a population health approach. The training needs analysis identified very little difference between the education and training needs across the rural and remote health disciplines; it was perceived that they managed chronic disease fairly well yet found prevention and early detection to be at the 'hard end'. The main barriers identified were the demands of acute care over chronic disease management, compounded by high workforce turnover in remote areas. The curriculum framework, in particular the domains of remote practice, is being used by several Australian universities, health departments and non-government organisations in adapting their existing or new education programs. The self-assessment tool was based on the curriculum outcomes and was piloted in 2005 and found to be very useful for pre- and post-training purposes and as a discussion starter for all disciplines and groups.

CONCLUSIONS

A practical curriculum framework now exists to integrate a population health approach for the prevention and early detection of chronic disease when educating the primary healthcare workforce. It is relevant to all health disciplines and is flexible in that it can be adapted, or adopted, depending on the educational needs of the disciplinary group. It is being imbedded into numerous undergraduate, postgraduate, and professional development programs in Australia. It includes: the core learning outcomes expected of any workforce, resources, and a self-assessment tool in chronic disease. These tools are assisting educators in the required paradigm shift required of the workforce to alter the single disease based practice model towards a comprehensive and integrated population based approach required for the workforce in the 21st century.

Alcohol intake, consumption pattern and beverage type, and the risk of Type 2 diabetes

AIMS

To examine associations between amount and frequency of alcohol consumption, and Type 2 diabetes.

METHODS

A prospective study of 36 527 adults aged 40-69 at baseline. Incident cases of Type 2 diabetes were identified by questionnaire 4 years later. Sex-specific logistic regression models, adjusting for country of birth, dietary glycaemic index, energy intake and age, and in a second model body mass index (BMI) and waist-hip ratio (WHR), were used.

RESULTS

Diabetes status was ascertained for 31 422 (86%) participants, and 362 cases identified. Former drinkers had higher risks than lifetime abstainers. Female drinkers had lower risk than lifetime abstainers (ORs < 10 g/day 0.54, 95% CI 0.36-0.82; 10-19.9 g/day 0.57, 0.34-0.94; > or = 20 g/day 0.46, 0.24-0.88, P trend = 0.005). There was no relationship after adjustment for body size. For men, a weak inverse association was observed after adjustment for body size (ORs relative to lifetime abstainers: < 10 g/day 1.56, 0.95-2.55; 10-19.9 g/day 1.21, 0.69-2.10; 20-29.9 g/day 0.80, 0.40-1.60; = 30 g/day 0.86, 0.50-1.58, P trend = 0.036). Wine was the only beverage for which an inverse association was observed. Compared with men who did not drink in the week before baseline, men who drank > or = 210 g over 1-3 days had an increased risk of diabetes (OR 5.21, 1.79-15.19), while the same amount over more days did not increase risk.

CONCLUSIONS

Total alcohol intake was associated with reduced risk only in women. Alcohol from wine was associated with reduced risk of Type 2 diabetes. A high daily intake of alcohol, even on only 1-3 days a week, may increase the risk of diabetes in men.

Differential association of C-reactive protein with adiposity in men and women in an Aboriginal community in northeast Arnhem Land of Australia

OBJECTIVE

To examine the relationship between C-reactive protein (CRP), adiposity and other metabolic abnormalities in an Aboriginal community in Northern Australia.

DESIGN

Cross-sectional analysis of data obtained between 2001 and 2003 from 379 Aboriginal people residing in a geographically isolated community.

RESULTS

Mean (95% CI) CRP in women and men was 4.06 cholesterol (3.53, 4.66) mg/l and 3.42 (2.94, 3.97) mg/l, respectively (P=NS). The prevalence of the metabolic syndrome (US National Cholesterol Education [corrected] Program (NCEP) definition) was significantly higher for women than men (41 vs 18%, chi (2)=20.94, P<0.001). C-reactive protein correlated strongly with adiposity in women (waist circumference, waist to hip ratio and body mass index; r>/=0.514, P<0.01) but much less strongly in men (r</=0.221, P<0.05). In a multivariate stepwise linear regression model, waist circumference was the strongest independent predictor explaining 35% of CRP concentration variance in women, but only 5.4% in men (WHR). Incremental increases in CRP concentration across four BMI categories were significant in women (P (linear trend)<0.001) but not in men.

CONCLUSIONS

High CRP levels in the surveyed population are consistent with the high prevalence of vascular disease morbidity and mortality in Aboriginal Australians. The relationship of CRP with increasing body fat was strong and consistent in women but not in men. Prospective studies are needed to elucidate the role of CRP (if any) as a predictive marker for cardiovascular events in this high-risk population.

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.

Screening for diabetes in Indigenous populations using glycated haemoglobin: sensitivity, specificity, post-test likelihood and risk of disease

AIMS

Screening for diabetes using glycated haemoglobin (HbA1c) offers potential advantages over fasting glucose or oral glucose tolerance testing. Current recommendations advise against the use of HbA1c for screening but test properties may vary systematically across populations, according to the diabetes prevalence and risk. We aimed to: (i) characterize the properties of test cut-offs of HbA1c for diagnosis of diabetes relative to a diagnosis based on a fasting plasma glucose concentration of 7.0 mmol/l for high-risk Indigenous populations; and (ii) examine test properties across a range of diabetes prevalence from 5 to 30%.

METHODS

Data were collected from Aboriginal and Torres Strait Islander communities in Australia and a Canadian First Nations community (diabetes prevalence 12-22%) in the course of diabetes diagnostic and risk factor screening programmes (n = 431). Screening test properties were analyzed for the range of HbA1c observed (3-12.9%).

RESULTS

In separate and pooled analyses, a HbA1c cut point of 7.0% proved the optimal limit for classifying diabetes, with summary analysis results of sensitivity = 73 (56-86)%, specificity = 98 (96-99)%, overall agreement (Youden's index) = 0.71, and positive predictive value (for an overall prevalence of 18%) = 88%. For diabetes prevalence from 5 to 30% the post-test likelihood of having diabetes given HbA1c = 7.0% (positive predictive value) ranged from 62.7 to 93.2%; for HbA1c < 7.0%, the post-test likelihood of having diabetes ranged from 4.5 to 27.7%.

CONCLUSIONS

The results converge with research on the likelihood of diabetes complications in supporting a HbA1c cut-off of 7.0% in screening for diabetes in epidemiological research. Glycated haemoglobin has potential utility in screening for diabetes in high-risk populations.

Arabinoxylan fibre improves metabolic control in people with Type II diabetes

OBJECTIVE

To determine whether diet supplementation with arabinoxylan-rich (AX)-fibre from wheat improves glycaemic control in Type II diabetes.

DESIGN

Randomized, crossover intervention trial.

SETTING

Monash Medical Centre.

SUBJECTS

A total of 15 subjects with Type II diabetes.

INTERVENTIONS

Over two 5-week periods, subjects supplemented their usual diet with control bread and muffins (50% whole wheat, 50% white flour) (control diet) or with AX-bread and muffins (50% whole wheat, 36% white flour, 14% AX fibre) (AX diet). Subjects completed a 7-day food diary. At 0 and 5 weeks, venous blood was collected for determination of fasting and 2 h glucose, insulin, fructosamine and blood lipids. Blood pressure, body weight and body fat were also determined. A 24 h faecal sample, from 12 subjects, was weighed and analysed for faecal polysaccharide as a marker for dietary compliance.

RESULTS

Control and AX diets were similar except the AX diet supplied an additional 15.1 (12.0-18.5) (mean (95% confidence intervals)) g/day dietary fibre (P=0.000). Consumption of the AX diet increased faecal output by 61.5 (0.2-122.8) g/day (P=0.05) on a wet weight basis and significantly lowered fasting and 2 h plasma glucose, 2 h insulin and serum fructosamine (P=0.002, 0.000, 0.015, and 0.02, respectively). Blood lipids, body weight, fat mass and blood pressure remained unchanged.

CONCLUSION

A supplement of 15 g/day of AX-rich fibre can significantly improve glycaemic control in people with Type II diabetes.

Kava use, dyslipidaemia and biomarkers of dietary quality in Aboriginal people in Arnhem Land in the Northern Territory (NT), Australia

Heavy kava use has been associated with sudden death in Aboriginal Australians in Arnhem Land (Northern Territory, Australia) where poor diets and a high incidence of premature coronary heart disease are known. Heavy kava users may suffer additional risk if further malnourished. Among 98 people (62 males, 36 females) in one community, 36 never used kava, 26 were past users, and 36 were continuing users. Across kava-using groups skinfold thickness, body mass index and body fat decreased. Total- and LDL-cholesterol were elevated in kava users compared to both former users and never users. HDL-cholesterol was higher in current users vs never users. Across kava-using groups, triglycerides, homocysteine and diet-derived antioxidant vitamins alpha-tocopherol and retinol, did not vary. Plasma carotenoid levels (indicative of vegetable and fruit intake) were very low, but when adjusted for plasma cholesterol, did not vary between kava-using groups. An obsession for kava drinking may mediate kava's direct effects on nutritional status.

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.

Relation of adiposity and body fat distribution to body mass index in Australians of Aboriginal and European ancestry

OBJECTIVE

To compare the relations of adiposity and body fat distribution to body mass index (BMI) in Australians of Aboriginal and European ancestry.

DESIGN

Cross-sectional volunteer samples.

SETTING

Australian Aboriginal communities in remote central and northern Australia, urban European Australians resident in Melbourne, Australia.

SUBJECTS

Healthy Aboriginal (130 women, 120 men) and European Australians (100 women, 47 men) with a BMI<30 kg/m(2), aged 18-35 y; all women were nonpregnant.

INTERVENTIONS

Anthropometric variables and resistance-using a four-terminal impedance plethysmograph-were measured.

RESULTS

Aboriginal women and men were significantly shorter and weighed less than European Australians (P<0.05). Aboriginal women had a significantly larger waist circumference and waist-to-hip ratio (WHR, P<0.0005) compared to European Australian women. The sum of four skinfold thicknesses (SFT) (S4) and trunk SFT was higher in Aboriginals as compared to European Australian women (P<0.0005); however, limb SFT tended to be lower (P=0.06). On the other hand, BMI was significantly lower in Aboriginals compared to European Australian men (P=0.011), as was hip circumference (P=0.001); however, WHR was significantly (P=0.007) higher. On regression analysis, Aboriginal women and men were significantly heavier than European Australians for the same height(2)/resistance (surrogate for fat-free mass) and S4 (surrogate for subcutaneous fat); and that Aboriginal men had a significantly higher BMI (by 1.2 kg/m(2); P<0.0005) for any given S4 and height(2)/resistance values, compared to European Australian men.

CONCLUSION

Aboriginal and European Australians have a significantly different body fat distribution and fat mass for a given body weight or BMI. Use of the World Health Organization recommended BMI ranges to determine weight status may be inappropriate in Australian Aboriginal people.

Identification and quantitation of major carotenoids in selected components of the Mediterranean diet: green leafy vegetables, figs and olive oil

OBJECTIVE

To characterize the carotenoid content of selected components of the Mediterranean diet commonly eaten by Greek migrants to Melbourne, a population group maintaining a traditional dietary regimen, and who exhibit relatively high circulating carotenoid concentrations and low cardiovascular disease mortality. DESIGN AND SPECIMENS: Opportunistic sampling of wild (sow thistle, amaranth, purslane and dandelion, collected from roadsides and home gardens) and commercially available (chicory, endive) green leafy vegetables and figs in season. Foods were selected on the basis that they are commonly eaten by Greek migrants but not by Anglo-Celtic persons, and had not previously been well-characterized with respect to their carotenoid contents. Extra virgin, cold-pressed olive oil and 'extra light' olive oil were obtained from commercial sources. Specimens were extracted with tetrahydrofuran (or chloroform:methanol for olive oil) and carotenoid contents were quantified using HPLC with UV detection. Two to six specimens of greens and figs were analysed. Dietary intake was assessed by food frequency questionnaire.

RESULTS

Wild green vegetables contained high concentrations of lutein (sow thistle>amaranth>purslane>dandelion) and beta-carotene (sow thistle>amaranth>purslane=dandelion). Sow thistle and amaranth contained lutein (15 and 13 mg/100 g, respectively) and beta-carotene (3.3 and 4.0 mg/100 g, respectively) at concentrations greater than that seen in the commercially available species of chicory and endive. Figs contained all major carotenoids appearing in plasma, albeit at low concentrations. Extra virgin cold-pressed olive oil contained substantial quantities of lutein and beta-carotene, but the more-refined 'extra light' olive oil did not.

CONCLUSIONS

These components of the traditional Mediterranean diet contribute to the higher circulating concentrations of carotenoids in Greek migrants compared to Anglo-Celtic Australians.

SPONSORSHIP

This study largely funded by the National Health and Medical Research Council of Australia (grant no. 974098). Extra virgin olive oil donated by Picuba Foods, Marrickville, NSW, Australia.

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.

The influence of the type of dietary fat on postprandial fat oxidation rates: monounsaturated (olive oil) vs saturated fat (cream)

OBJECTIVE

To compare postprandial whole-body fat oxidation rates in humans, following high-fat (43% of total energy) mixed breakfast meals, of fixed energy and macronutrient composition, rich in either monounsaturated fat (MUFA) from extra virgin olive oil or saturated fat (SFA) from cream.

DESIGN

Paired comparison of resting metabolic rate (RMR), thermic effect of a meal and substrate oxidation rates following consumption of isocaloric breakfast meals, differing only in the type of fat, administered in random order 1-2 weeks apart.

SUBJECTS

Fourteen male volunteers, body mass index (BMI) in the range 20-32 kg/m(2), aged 24-49 y and resident in Melbourne, Australia, were recruited by advertisement in the local media or by personal contact.

MEASUREMENTS

Body size and composition was determined by anthropometry and dual energy X-ray absorptiometry (DEXA). Indirect calorimetry was used to measure RMR, thermic effect of a meal, post-meal total energy expenditure and substrate oxidation rate. Blood pressure and pulse rates were measured with an automated oscillometric system. Fasting and 2 h postprandial glucose and insulin concentrations and the fasting lipid profile were also determined.

RESULTS

In the 5 h following the MUFA breakfast, there was a significantly greater postprandial fat oxidation rate (3.08+/-4.58 g/5 h, P=0.017), and lower postprandial carbohydrate oxidation rate (P=0.025), than after the SFA breakfast. Thermic effect of a meal was significantly higher (55 kJ/5 h, P=0.034) after the MUFA breakfast, in subjects with a high waist circumference (HWC > or = 99 cm) than those with a low waist circumference (LWC<99 cm). This difference was not detected following the SFA breakfast (P=0.910).

CONCLUSION

If postprandial fat oxidation rates are higher after high MUFA, rather than SFA meals, then a simple change to the type of dietary fat consumed might have beneficial effects in curbing weight gain in men consuming a relatively high-fat diet. This may be particularly evident in men with a large waist circumference.

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.

Diabetes in Australian aboriginal and Torres Strait Islander peoples

Type 2 diabetes arises from a complex and multifactorial set of factors, including genetic susceptibility, behaviour (including diet and exercise), early nutrition, obesity and psychosocial stress, leading to insulin resistance and pancreatic failure. These factors in turn are influenced by social and physical environmental factors. Each of these may be important determinants of the high prevalence and incidence of type 2 diabetes in Australian Aboriginal and Torres Strait Islander people. Public health interventions for primary and secondary prevention need to recognize this complexity. Although a reduction in the prevalence of obesity or diabetes in the short-medium term is rarely if ever achieved, there are documented examples of community-based programs which have been effective in reducing the risk of developing type 2 diabetes and its cardiovascular complications. Such interventions need to be community-directed and appropriate to local circumstances in order to be effective.

Importance of retaining a national dietary guideline for sugar

The Australian Dietary Guidelines are currently being revised and updated. There has been public discussion about the advisability of retaining a guideline for sugar because of insufficient evidence linking sugar consumption to ill health. However, there are concerns about the quality of the self-reported food intake data on which this conclusion is based. In addition, the doubling in diabetes prevalence in Australia in the past 20 years, which is linked to increased obesity from consumption of energy-dense foods, including those with added sugars (sugar-sweetened drinks being particularly important), provides a strong rationale for retaining a dietary guideline for sugar.

Is a low fat diet the optimal way to cut energy intake over the long-term in overweight people?

Successful weight loss depends on maintaining a sustained negative energy balance. This can be achieved on diets with a normal (40% energy) fat content as well as on low fat diets. Using a 'modified fat' (MF) diet enriched with monounsaturated fat (MUFA), body weight may be lost either by calorie counting, or by allowing ad libitum food intake with careful food selection. In the latter approach high energy, high MUFA foods (predominantly olive oil, but also may include nuts and avocado) should contribute no more than 20% total energy to the diet, and other foods should be selected to minimise meal energy density. This can be achieved simply by the consumption of a wide variety of vegetables and whole grain cereal foods. It is also important to restrict foods high in saturated fat and to encourage regular exercise. Such a 'modified fat' low energy diet designed for weight loss should also contribute numerous health benefits in relation to improved metabolic control in Type 2 diabetes and reduced cardiovascular disease risk (as the diet is not only rich in MUFA but also in a range of dietary antioxidants and other bio-active phytochemicals).

Insulin resistance as a major determinant of increased coronary heart disease risk in postmenopausal women with Type 2 diabetes mellitus

AIM

To investigate the risk factors associated with clinically defined coronary heart disease (CHD) in women with Type 2 diabetes mellitus (DM).

METHODS

CHD status was assessed via standard history and resting electrocardiogram in 41 postmenopausal diabetic and 41 age- and body mass index-matched normoglycaemic women recruited from a community-based cohort. The following parameters were assessed: body composition by dual energy X-ray absorptiometry, blood pressure, metabolic and lipoprotein profile and haemostatic factors.

RESULTS

Diabetic women with CHD (n = 14) had greater insulin resistance, calculated by homeostasis model assessment (10.2 (7.0-14.8) vs. 6.5 (5.5-7.7), P = 0.010), and higher plasminogen activator inhibitor-1 (PAI-1) levels (45 (29-69) vs. 24 (19-32) ng/ml, P = 0.013), than those without CHD. They also had higher triglycerides (2.9 (2.2-3.8) vs. 2.1 (1.8-2.4) mmol/l, P = 0.016) and a trend towards reduced low-density lipoprotein particle size (25.5 +/- 0.6 vs. 25.8 +/- 0.5 nm, P = 0.097). In a logistic regression model, insulin resistance was a significant independent predictor of CHD status (odds ratio = 1.33, 95% confidence interval = 1.06-1.68, P = 0.015). In contrast, in normoglycaemic women the major risk factors for CHD were elevated cholesterol, apolipoprotein(a), apolipoprotein B and systolic blood pressure (P = 0.018, P = 0.016, P = 0.006 and P = 0.049, respectively).

CONCLUSIONS

Increased insulin resistance in association with elevated PAI-1 and dyslipidaemia appears to underpin the increased risk of CHD in women with Type 2 DM. Therapeutic approaches that increase insulin sensitivity may serve to reduce CHD risk in this vulnerable group. Diabet. Med. 18, 476-482 (2001)

Lipids and psychosocial status in aboriginal persons with and at risk for Type 2 diabetes: implications for tertiary prevention

This study assessed psychosocial correlates of dyslipidemia, towards enabling improved tertiary prevention of macrovascular complications of diabetes mellitus (DM). We tested the hypothesis that psychosocial measures are related to high-density lipoprotein cholesterol (HDL-C) and triglyceride concentrations in a rural aboriginal population in British Columbia, Canada. Persons sampled were on-reserve registered Indians (n=198) with and at risk for Type 2 DM. Relationships between HDL-C and psychosocial variables were associated with glycemic status. For persons with diabetes and impaired glucose tolerance (n=44), quality of life and mastery were positively related (P<0.001), and depression inversely related (P<0.001), to HDL-C. An apparent lack of effect of behavior suggests the influence of emotional pathways involving autonomic-neuroendocrine axes. We recommend assessing mental health, and promoting mastery and diabetes quality of life through empowerment oriented diabetes management strategies, in negotiating culturally acceptable treatment of diabetic dyslipidemia for aboriginal people.

Plasma leptin concentrations, basal metabolic rates and respiratory quotients in young and older adults

OBJECTIVE

To-examine the interrelationship of circulating leptin concentrations, basal metabolic rates (BMR) and respiratory quotients (RQ) in young and older adults.

DESIGN

Cross sectional study.

SUBJECTS

Seventy-six Australian men and women, 48 young (< 35 y) and 28 older ( > or = 50 y).

MEASUREMENTS

Fasting plasma leptin concentrations by RIA, BMR and RQ by indirect calorimetry, percentage body fat (BF%), fat mass (FM) and fat-free mass (FFM) from total body water (TBW) based on deuterium dilution, waist and hip circumferences from anthropometry.

RESULTS

Older subjects had significantly higher BF%, FM and waist-to-hip ratio (WHR), but significantly lower FFM and absolute BMR as compared to younger subjects. Absolute leptin concentrations were 60% higher in older subjects but did not achieve statistical significance. There was, however, a significant gender x age group interaction in leptin concentrations. This was reflected in a significant inverse relationship between age group and leptin in women when data was controlled for waist circumference (r = -0.38, P = 0.028), or FM (r = -0.36, P = 0.042). A similar relationship was not observed in men on controlling for BF% or FM. Log transformed plasma leptin was best explained by a model that included BF%, gender, age-group, gender x age-group and WHR r = 0.75, adjusted r2 = 0.56, standard error of estimate (SEE) = 0.73 ng/ml). BMR was best explained by FFM, FM and age group r = 0.94, adjusted r2 = 0.87; SEE = 429 kJ/day). On controlling for BF%, WHR and FFM, leptin was negatively related to RQ only in older men (r = -0.67, P = 0.033). There was no relationship of leptin to BMR in the groups studied.

CONCLUSION

The study demonstrates an age-related modification of the gender bias in leptin, and a gender-specific inverse relationship between leptin and RQ in older people. The decline in leptin and the lack of a relationship between RQ and leptin in older women may indicate an increased risk of weight gain relative to older men.