Nanomaterials by design: a review of nanoscale metallic multilayers

Nanoscale metallic multilayers have been shown to have a wide range of outstanding properties, which differ to a great extent from those observed in monolithic films. Their exceptional properties are mainly associated with the large number of interfaces and the nanoscale layer thicknesses. Many studies have investigated these materials focusing on magnetic, mechanical, optical, or radiation tolerance properties. Thus, this review provides a summary of the findings in each area, including a description of the general attributes, the adopted synthesis methods and most common characterization techniques used. This information is followed by a compendium of the material properties and a brief discussion of related experimental data, as well as existing and promising applications. Other phenomena of interest, including thermal stability studies, self-propagating reactions and the progression from nano multilayers to amorphous and/or crystalline alloys, are also covered. In general, this review highlights the use of nano multilayer architectures as viable routes to overcome the challenges of designing and implementing new engineering materials at the nanoscale.

No association between circulating concentrations of vitamin D and risk of lung cancer: an analysis in 20 prospective studies in the Lung Cancer Cohort Consortium (LC3)

Background

There is observational evidence suggesting that high vitamin D concentrations may protect against lung cancer. To investigate this hypothesis in detail, we measured circulating vitamin D concentrations in prediagnostic blood from 20 cohorts participating in the Lung Cancer Cohort Consortium (LC3).

Patients and methods

The study included 5313 lung cancer cases and 5313 controls. Blood samples for the cases were collected, on average, 5 years before lung cancer diagnosis. Controls were individually matched to the cases by cohort, sex, age, race/ethnicity, date of blood collection, and smoking status in five categories. Liquid chromatography coupled with tandem mass spectrometry was used to separately analyze 25-hydroxyvitamin D2 [25(OH)D2] and 25-hydroxyvitamin D3 [25(OH)D3] and their concentrations were combined to give an overall measure of 25(OH)D. We used conditional logistic regression to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for 25(OH)D as both continuous and categorical variables.

Results

Overall, no apparent association between 25(OH)D and risk of lung cancer was observed (multivariable adjusted OR for a doubling in concentration: 0.98, 95% CI: 0.91, 1.06). Similarly, we found no clear evidence of interaction by cohort, sex, age, smoking status, or histology.

Conclusion

This study did not support an association between vitamin D concentrations and lung cancer risk.

Dietary inflammatory index or Mediterranean diet score as risk factors for total and cardiovascular mortality

BACKGROUND AND AIMS

Dietary patterns are associated with risk of cardiovascular disease (CVD). We aimed to examine associations of the Dietary Inflammatory Index (DII) and the Mediterranean Diet Score (MDS) with total, cardiovascular disease (CVD) and coronary heart disease (CHD) mortality in the Melbourne Collaborative Cohort Study; and compare the strengths of the associations.

METHODS AND RESULTS

In our prospective cohort study of 41,513 men and women aged 40-69 years, a food frequency questionnaire was completed at baseline and mortality data were obtained via linkage with local and national registries over an average of 19 years follow up. At baseline, questionnaires were completed and physical measures and blood samples taken. Cox proportional hazards models, adjusting for age, alcohol consumption, sex, region of origin, personal history of CVD or diabetes and family history of CVD, were used to assess associations between dietary scores and mortality. More Mediterranean or less inflammatory diets were associated with lower total, CVD and CHD mortality. The hazard ratio for total mortality comparing the highest and lowest quintiles was 1.16 (95%CI: 1.08-1.24) for DII; and 0.86 (95%CI: 0.80-0.93) comparing the highest and lowest three categories of MDS. Using the Bayesian information criterion, there was no evidence that the DII score was more strongly associated with total and CVD mortality than was the MDS.

CONCLUSIONS

The MDI and the DII show similar associations with total and cardiovascular mortality, consistent with the consensus that plant-based diets are beneficial for health.

Novel associations between blood DNA methylation and body mass index in middle-aged and older adults

BACKGROUND/OBJECTIVES

There is increasing evidence of a relationship between blood DNA methylation and body mass index (BMI). We aimed to assess associations of BMI with individual methylation measures (CpGs) through a cross-sectional genome-wide DNA methylation association study and a longitudinal analysis of repeated measurements over time.

SUBJECTS/METHODS

Using the Illumina Infinium HumanMethylation450 BeadChip, DNA methylation measures were determined in baseline peripheral blood samples from 5361 adults recruited to the Melbourne Collaborative Cohort Study (MCCS) and selected for nested case-control studies, 2586 because they were subsequently diagnosed with cancer (cases) and 2775 as controls. For a subset of 1088 controls, these measures were repeated using blood samples collected at wave 2 follow-up, a median of 11 years later; weight was measured at both time points. Associations between BMI and blood DNA methylation were assessed using linear mixed-effects regression models adjusted for batch effects and potential confounders. These were applied to cases and controls separately, with results combined through fixed-effects meta-analysis.

RESULTS

Cross-sectional analysis identified 310 CpGs associated with BMI with P<1.0 × 10^-7, 225 of which had not been reported previously. Of these 225 novel associations, 172 were replicated (P<0.05) using the Atherosclerosis Risk in Communities (ARIC) study. We also replicated using MCCS data (P<0.05) 335 of 392 associations previously reported with P<1.0 × 10^-7, including 60 that had not been replicated before. Associations between change in BMI and change in methylation were observed for 34 of the 310 strongest signals in our cross-sectional analysis, including 7 that had not been replicated using the ARIC study.

CONCLUSIONS

Together, these findings suggest that BMI is associated with blood DNA methylation at a large number of CpGs across the genome, several of which are located in or near genes involved in ATP-binding cassette transportation, tumour necrosis factor signalling, insulin resistance and lipid metabolism.

Dietary inflammatory index, Mediterranean diet score, and lung cancer: a prospective study

PURPOSE

To investigate prospectively the associations of Dietary Inflammatory Index (DII) and Mediterranean Diet Score (MDS) with lung cancer.

METHODS

We used data from men and women aged 40-69 years at recruitment in 1990-1994, who were participants in the Melbourne Collaborative Cohort Study (n = 35,303). A total of 403 incident lung cancer cases were identified over an average 18-year follow-up. Hazard ratios (HR) were estimated using Cox regression, adjusting for smoking status and other risk factors, with age as the time metric.

RESULTS

An inverse correlation was observed between the DII and MDS (ρ = -0.45), consistent with a higher DII being pro-inflammatory and less 'healthy,' while a high MDS reflects a 'healthier' diet. The DII was positively associated with risk of lung cancer in current smokers [HRQ4 vs Q1 = 1.70 (1.02, 2.82); Ptrend = 0.008] (p interaction between DII quartiles and smoking status = 0.03). The MDS was inversely associated with lung cancer risk overall [HR7-9 vs 0-3 = 0.64 (0.45, 0.90); Ptrend = 0.005] and for current smokers (HR7-9 vs 0-3 = 0.38 (0.19, 0.75); Ptrend = 0.005) (p interaction between MDS categories and smoking status = 0.31).

CONCLUSIONS

The MDS showed an inverse association with lung cancer risk, especially for current smokers. A high DII, indicating a more pro-inflammatory diet, was associated with risk of lung cancer only for current smokers. A healthy diet may reduce the risk of lung cancer, especially in smokers.

Note: A method for minimizing oxide formation during elevated temperature nanoindentation

A standardized method to protect metallic samples and minimize oxide formation during elevated-temperature nanoindentation was adapted to a commercial instrument. Nanoindentation was performed on Al (100), Cu (100), and W (100) single crystals submerged in vacuum oil at 200 °C, while the surface morphology and oxidation was carefully monitored using atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The results were compared to room temperature and 200 °C nanoindentation tests performed without oil, in order to evaluate the feasibility of using the oil as a protective medium. Extensive surface characterization demonstrated that this methodology is effective for nanoscale testing.

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.

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.

Effect of fatty acids on bone marrow lesions and knee cartilage in healthy, middle-aged subjects without clinical knee osteoarthritis

OBJECTIVE

There is evidence that omega-3 polyunsaturated fatty acids alleviate the progression of osteoarthritis (OA). However, little work has been done to investigate the effect of fatty acids on bone marrow lesions and knee cartilage in healthy subjects. We examined this in a cohort of healthy middle-aged subjects without clinical knee OA.

METHODS

Two hundred and ninety-three healthy adults without knee pain or injury were recruited from an existing community-based cohort. Intakes of fatty acids and food sources of these were estimated from a food frequency questionnaire at baseline. Tibial cartilage volume, tibial plateau bone area, tibiofemoral cartilage defects and bone marrow lesions were assessed approximately 10 years later using magnetic resonance imaging.

RESULTS

In multivariate analyses, higher intakes of monounsaturated fatty acids (OR=2.14, 95% CI 1.04-4.39, P=0.04), total (OR=1.77, 95% CI 1.13-2.77, P=0.01) and n-6 polyunsaturated fatty acids (OR=1.69, 95% CI 1.10-2.61, P=0.02) were associated with an increased risk of bone marrow lesions. Intake of fatty acids was not significantly associated with cartilage volume or cartilage defects.

CONCLUSION

These findings support the dietary recommendation towards a shift to foods rich in n-3 polyunsaturated fatty acids in order to maintain an optimal balance between dietary n-3 and n-6 polyunsaturated fatty acids, which is also important in the prevention of atherosclerosis. Although our findings will need to be confirmed in longitudinal studies, they suggest the potential of fatty acids to adversely effect the knee joint.

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.

Leptin and other components of the Metabolic Syndrome in Mauritius--a factor analysis

OBJECTIVE

To use factor analysis to examine the putative role of leptin in the Metabolic Syndrome, and to define better the associations among observed variables and the identified factors.

DESIGN

Factor analysis of cross-sectional data from a 1987 survey.

SUBJECTS

Non-diabetic residents of Mauritius who participated in population-based surveys in 1987 and 1992 (1414 men and 1654 women).

MEASUREMENTS

Fasting and 2 h plasma glucose and insulin following a 75 g oral glucose load; seated blood pressure; body mass index (BMI); waist-to-hip ratio (WHR); and fasting serum triglycerides, HDL-cholesterol, leptin and uric acid concentrations.

RESULTS

Principal components factor analysis revealed three factors for men and women that explained between 54 and 55% of the observed variance of the 12 measured variables. General features of these factors were as follows: factor 1, WHR, BMI, leptin, fasting and 2 h insulin, triglycerides, and HDL-cholesterol; factor 2, systolic and diastolic blood pressure, uric acid (men only), and fasting glucose (women only); and factor 3, fasting and 2 h glucose and insulin. Only three variables loaded on more than one factor with a loading > or = 0.4 (fasting and 2 h insulin, fasting glucose in women only). Leptin loaded on one factor only in both men and women.

CONCLUSIONS

Since multiple factors underlie the Metabolic Syndrome, and since no observed variable loads on all three factors, more than one mechanism might account for the observed clustering of risk characteristics. Leptin does not unite features of this syndrome due to its loading on one factor only. Uric acid is related to a different factor in men and women. The absence of gender differences in factor loadings argues for similar mechanisms for the Metabolic Syndrome in men and women in Mauritius. International Journal of Obesity (2001) 25, 126-131

Impaired fasting glucose: how low should it go?

OBJECTIVE

Impaired fasting glucose (IFG) has been recently introduced as a stage of abnormal carbohydrate metabolism, but the evidence on which its glucose limits (fasting plasma glucose [FPG] 6.1-6.9 mmol/l) are based is not strong. The aim of this study was to determine if 6.1 mmol/l represents a clear cutoff in terms of the risk of future diabetes and in terms of elevated cardiovascular risk factor levels, and to examine the use of other lower limits of IFG.

RESEARCH DESIGN AND METHODS

A population-based survey of the island of Mauritius was undertaken in 1987, with a follow-up survey 5 years later. On both occasions, an oral glucose tolerance test was performed and cardiovascular risk factors were measured.

RESULTS

Data were available from 4,721 nondiabetic people at baseline, and from 3,542 at follow-up. At baseline, blood pressure, lipids, and obesity increased in a linear fashion with increasing FPG, with no evidence of a threshold effect. The risk of developing hypertension at follow-up was greater for those people with baseline FPG > or =6.1 mmol/l (P<0.001). The risk of developing diabetes at follow-up increased with increasing baseline FPG, but there was little evidence of a threshold near 6.1 mmol/l.

CONCLUSIONS

Cardiovascular risk and risk of future diabetes increase continually with increasing FPG, and there is no threshold value on which to base a definition of IFG. If a lower limit of approximately 5.8 mmol/l is used, the category defines a group more similar to the group with impaired glucose tolerance, with regard to total prevalence and the risk of subsequent diabetes.

Isolated post-challenge hyperglycaemia confirmed as a risk factor for mortality

AIMS/HYPOTHESIS

The aim of this study was to examine the possible link between isolated post-challenge hyperglycaemia (2-h post-challenge plasma glucose >/= 11.1 mmol/l, and fasting plasma glucose < 7.0 mmol/l) and mortality.

METHODS

The data from three population based longitudinal studies (in Mauritius, Fiji and Nauru) were pooled and mortality rates were determined in 9179 people who were followed for between 5 and 12 years.

RESULTS

There were 595 people with previously diagnosed diabetes, and 799 with newly diagnosed diabetes, of whom 243 (31) had isolated post-challenge hyperglycaemia. In comparison with people without diabetes, people with isolated post-challenge hyperglycaemia had an increased risk of all-cause mortality [Cox proportional hazards ratio (95 % CI): 2.7 (1.8-3.9) - men; 2.0 (1.3-3.3) - women], and of cardiovascular mortality [2.3 (1.2-4.2) - men; 2.6 (1.3-5.1) - women]. In addition, men with isolated post-challenge hyperglycaemia had a high risk of cancer death [8.0 (3.6-17.9)].

CONCLUSION/INTERPRETATION

These data show that isolated post-challenge hyperglycaemia, which can only be identified by the 2-h glucose, is common, and at least doubles the mortality risk. This should be considered in the design of screening programmes that use only fasting glucose.

Combination of polymorphisms in OB-R and the OB gene associated with insulin resistance in Nauruan males

OBJECTIVE

To investigate the relationship between polymorphisms in the OB-R and OB genes and metabolic markers for obesity and glucose intolerance in a population of Nauruan men. In addition, we examined the effect of the simultaneous presence of the three polymorphisms on the phenotype of individuals in this population.

DESIGN AND SUBJECTS

This study was conducted in a population from the Pacific Island of Nauru. Populations in this region have some of the highest recorded rates of obesity and type 2 diabetes and are therefore of great interest in the genetic analysis of these diseases. Two hundred and thirty-two male subjects were examined in this cross-sectional study. All subjects were non-diabetic and the group had a mean age of 31 y and a mean body weight of 104 kg.

MEASUREMENTS

Several phenotypic measures of body fatness and fat distribution (anthropometry), fasting plasma insulin, glucose and leptin concentrations, blood pressure and 2 h plasma glucose concentration, genotypes of subjects for the Gln223Arg, PRO1019pro (OB-R gene) and OB gene polymorphisms.

RESULTS

Individually, the OB gene and Gln223Arg OB-R polymorphisms were not associated with the obese or glucose-intolerant phenotype in this population. Individuals with the PRO1019pro polymorphism were found to have elevated insulin concentrations and diastolic blood pressure (Pc = 0.04). In addition, individuals found to simultaneously exhibit homozygosity of the common allele of all three polymorphisms (genotypes: Arg/Arg, pro/pro and II/II) exhibited significantly elevated fasting insulin levels (Pc = 0.03).

CONCLUSIONS

Pacific Island populations exhibit a remarkably high prevalence rate of obesity and type 2 diabetes and represent a unique population for genetic studies of obesity. In the present study we have revealed that a specific combination of alleles in OB and OB-R, two candidate genes for obesity, may confer an increased risk for the development of insulin resistance in Nauruan males.

Diabetic neuropathy in Mauritius: prevalence and risk factors

The study of diabetic neuropathy has been primarily in Europids, despite the high prevalence of diabetes in other populations. We set out to ascertain the prevalence of diabetic neuropathy and its risk factors in the island nation of Mauritius. Population surveys were carried out in 1987 and 1992 in Mauritius to establish the prevalence of Type 2 diabetes. In the second survey, vibration perception threshold (VPT) was also measured at the great toe in 847 subjects with diabetes, 204 subjects with impaired glucose tolerance and 127 subjects with normal glucose tolerance. Neuropathy was defined as levels of VPT exceeding the mean plus 2 standard deviations defined separately for three age groups of Mauritian non-diabetic subjects. Risk factors for neuropathy were identified cross sectionally from the 1992 data, and longitudinally from the 1987 data. Neuropathy was detected in 8.3% of the 847 diabetic subjects (12.7%) of those with known diabetes, and 3.6% of those with newly diagnosed diabetes). Logistic regression identified diabetes duration (odds ratio [95% CI]; 1.08 [1.04-1.13] per year, P=0.0002), treatment with insulin or oral hypoglycaemic agents (2.63 [1.36-5.09], P=0.004) and greater height (1.36 [1.19-1.57] per 5 cm, P < 0.001) as risk factors for neuropathy, in the cross sectional analysis. In the longitudinal analysis, diabetes duration (1.11 [1.05-1.18] per year, P=0.001), fasting glucose (1.12 [1.03-1.22] per mmol/l, P=0.01) and height (1.23 [1.03-1.45] per 5 cm, P=0.02) were associated with neuropathy. A lower 2-h plasma insulin was also associated with neuropathy in the longitudinal analysis. The prevalence of diabetic neuropathy in Mauritius is the lowest reported for any population, but the risk factors associated with it are similar to those previously found.

Do leptin levels predict weight gain?--A 5-year follow-up study in Mauritius. Mauritius Non-communicable Disease Study Group

OBJECTIVE

To investigate whether relative baseline leptin levels predict long-term changes in adiposity and/or its distribution.

RESEARCH METHODS AND PROCEDURES

In a longitudinal study of 2888 nondiabetic Mauritians aged 25 years to 74 years who participated in population-based surveys in 1987 and 1992, changes in body mass index (BMI), waist/hip ratio (WHR), and waist circumference were compared between "hyperleptinemic," "normoleptinemic," and "hypoleptinemic" groups. "Relative leptin levels" were calculated as standardized residuals from the regression of log10 leptin on baseline BMI to provide a leptin measure independent of BMI. Analyses were performed within each sex. A linear regression model was used to assess the effect of standardized residuals on changes in BMI, WHR, and waist circumference, independent of baseline BMI, age, fasting insulin, and ethnicity.

RESULTS

After adjusting for age and baseline BMI by analysis of covariance, there was no difference in changes in BMI, WHR, or waist circumference between men with low, normal, or high relative leptin levels. Among women, there was a significant difference in deltaWHR across leptin groups, such that the largest increase occurred in the "normal" leptin group. For both men and women, the linear regression models explained approximately 10% of variation in dependent variables, and the only significant independent variables were age, BMI, and being of Chinese origin, compared with Indian origin.

DISCUSSION

These findings do not support a role for leptin concentration in predicting weight gain or changes in fat distribution in adults over a 5-year period.

Is there a relationship between leptin and insulin sensitivity independent of obesity? A population-based study in the Indian Ocean nation of Mauritius. Mauritius NCD Study Group

OBJECTIVE

It has been shown previously in smaller studies that fasting serum leptin and insulin concentrations are highly correlated, and insulin sensitive men have lower leptin levels than insulin resistant men matched for fat mass. We have examined the association between insulin resistance (assessed by fasting insulin) and leptin after controlling for overall and central adiposity in a population-based cohort.

DESIGN

Leptin levels were compared across insulin resistance quartiles within three categories of obesity (tertiles of body mass index (BMI)). Partial correlation coefficents and multiple linear regression models were used to assess the relationship between leptin and fasting insulin after adjusting for BMI and waist to hip ratio (WHR) or waist circumference.

SUBJECTS

Subjects were normoglycemic participants of a 1987 non-communicable diseases survey conducted in the multiethnic population of Mauritius. 1227 men and 1310 women of Asian Indian, Creole and Chinese ethnicity had normal glucose tolerance and fasting serum leptin measurements.

RESULTS

Mean serum leptin concentration increased across quartiles of fasting insulin in each BMI group and gender, after controlling for BMI, WHR and age. Furthermore, fasting insulin was a significant determinant of serum leptin concentration, independent of BMI and WHR, in both men and women. Similar results were found if waist circumference replaced BMI and WHR in the model.

CONCLUSION

These results suggest that insulin resistance/concentration may contribute to the relatively wide variation in leptin levels seen at similar levels of body mass or alternatively, leptin may play a role in the etiology of insulin resistance. Further studies will be important to determine whether the hyperleptinemia/insulin resistance relationship has a role in the natural history of obesity, Type 2 diabetes mellitus and the other metabolic abnormalities associated with insulin resistance.

The association of modernization with dyslipidaemia and changes in lipid levels in the Polynesian population of Western Samoa

BACKGROUND

Obesity and non-insulin-dependent diabetes mellitus (NIDDM) have increased in prevalence in Polynesian Western Samoans over the 13-year period 1978-1991, as the population undergoes an 'epidemiological transition'.

METHODS

We therefore investigated changes in the frequency of dyslipidaemia over the same period in adults aged 25-74 years, and examined factors associated with dyslipidaemia in cross-sectional and longitudinal data. Subjects were drawn from three geographically defined locations representing different degrees of modernization.

RESULTS

The age-standardized prevalence of dyslipidaemia increased in each location between 1978 (n = 1197) and 1991 (n = 1748) with the prevalence of hypercholesterolaemia (> or = 5.5 mmol/l) increasing from 18% to 36% (P < 0.001), and that of hypertriglyceridaemia (> or = 2.0 mmol/l) increasing from 9% to 15% (P < 0.001) in the capital city, Apia. In 1991 the highest serum concentrations of total, high density lipoprotein (HDL) and calculated low density lipoprotein (LDL) cholesterol were found in Poutasi (intermediate level of modernization), and the highest triglyceride levels in urbanized Apia. Higher levels of body mass index (BMI), waist-hip ratio (WHR), glucose intolerance, fasting insulin concentration, physical inactivity, educational level, and occupational status were all associated with adverse lipid levels in univariate data. Obesity (BMI in women, WHR in men) and survey location were the most important correlates of abnormal lipid levels in logistic regression models. Fasting insulin was also independently associated with high triglyceride levels in men, while in women the increasing levels of fasting insulin were associated with adverse levels of total, LDL and HDL cholesterol, and triglycerides. In longitudinal data (n = 311), lower baseline levels of cholesterol and triglycerides were associated with greater increases in either parameter at follow-up. Elevated fasting insulin and female gender also predicted increasing cholesterol concentrations, and urban residence predicted an increase in triglyceride levels.

CONCLUSIONS

Current levels of dyslipidaemia in Western Samoa are similar to those observed in developed Western populations, and are increasing rapidly. These findings, considered along with the high prevalence of other cardiovascular disease risk factors in Samoans, including smoking, obesity and NIDDM, suggest that cardiovascular disease will be a major health concern in the future.

Is leptin sensitivity the link between smoking cessation and weight gain?

The known association between smoking cessation and weight gain, and the suggested role of leptin in the control of body weight, led to the present study which examined the association between smoking and serum leptin concentrations. Mean serum leptin levels, independent of body mass index (BMI), were calculated in male smokers and non-smokers from Nauru, Western Samoa and Mauritius. Smokers were generally leaner than non-smokers, and of similar ages. Levels of physical activity and glucose tolerance status were similar for smokers and non-smokers in Nauru and Western Samoa, while in Mauritius smokers were more active and less likely to be diabetic. Leptin concentrations in smokers were significantly lower than in non-smokers, even after adjusting for BMI, waist/hip ratio (WHR) or waist girth (P < or = 0.04). This association was independent of diabetes status. Smoking, via nicotinic mechanisms, may modify the sensitivity of hypothalamic leptin receptors and consequently modulate leptin synthesis and reduce body weight.

Serum lipids and modernization in coastal and highland Papua New Guinea

Previous studies in Melanesians of Papua New Guinea have documented low serum cholesterol concentrations with no age-related rise and a virtual absence of coronary heart disease. However, because of recent reports of the emergence of coronary heart disease in this population, serum lipid concentrations in adults aged > or = 25 years in three coastal (n = 1,489 and three highland (n = 388) village communities at different stages of modernization were examined as part of a survey undertaken in 1991. Total cholesterol concentrations were clearly higher than were levels recorded in earlier studies. Moreover, age-related increases in total cholesterol, low density lipoprotein cholesterol (LDL cholesterol), high density lipoprotein cholesterol (HDL cholesterol), and triglycerides (in women) were apparent. Mean total cholesterol levels in an urban community with a high risk of diabetes were similar to those observed in Australians, while HDL cholesterol concentrations were lower. Total cholesterol and LDL cholesterol levels were higher in urban coastal and periurban highland subjects than in their rural counterparts. Prevalence of hypercholesterolemia (> or = 5.2 mmol/liter) varied from 16% in rural highlanders to 56% in urban coastal subjects. Sex, age, village, body mass index, fat distribution, glucose intolerance, physical activity, and an index of relative modernity all contributed to variations in cholesterol and triglyceride concentrations. These results show that Papua New Guineans are by no means protected from dyslipidemia and serve warning that, unless effective preventative strategies can be developed, this and similar rapidly developing populations can expect an increasing incidence of coronary heart disease.

Abdominal fat distribution and insulin levels only partially explain adverse cardiovascular risk profile in Asian Indians

BACKGROUND

Asian Indians show an increased risk of non-insulin-dependent diabetes mellitus (NIDDM) and coronary heart disease, together with adverse fat distribution and hyperinsulinaemia relative to other ethnic groups. Using population-based data, we investigated the question of whether the adverse fat distribution observed in Indians can be explained by differences in behavioural risk factor levels. We have examined the question of whether ethnic differences in fat distribution are responsible for the unfavourable risk factor profile of Indians.

SUBJECTS AND METHODS

Fat distribution (waist: hip ratio) was compared in population-based samples of Asian Indian (n = 4394), Creole (n = 1746), and Chinese (n = 425) Mauritians, after controlling for body mass index and other factors. The contribution of this ratio to ethnic differences in cardiovascular disease risk factors and the role of fasting insulin concentrations were also determined.

RESULTS

Indian men had the highest mean waist: hip ratio, despite having the lowest body mass index. In Indian women the mean waist: hip ratio and body mass index were intermediate between those of Chinese and Creole women. Indians of both sexes had low levels of high-density lipoprotein (HDL) cholesterol and HDL: total cholesterol compared with Creoles or Chinese, whereas triglycerides levels were highest in Indian men but intermediate in Indian women. Mean fasting and 2 h insulin concentrations were not consistently highest in the Indian subgroups. Blood pressure and serum urate levels were lowest in Indians of both sexes and Indian women also had lower total cholesterol concentrations than either Creoles or Chinese. The elevated waist: hip ratio in Indians was not explained by differences in physical activity, cigarette smoking, or alcohol consumption and the differences in this ratio (and insulin levels) did not explain the observed ethnic differences in metabolic parameters.

CONCLUSIONS

The susceptibility of Indians to abdominal obesity contributed to the less desirable levels of some, but not all, cardiovascular risk factors. Ethnic differences in cardiovascular risk factors in Mauritians were not explained by differences in abdominal obesity, serum insulin or behavioural risk factors. These data suggest that it is over-simplistic to ascribe the adverse cardiovascular risk factor profile commonly observed in Asian Indians to a tendency to abdominal obesity.

Microalbuminuria, cardiovascular risk factors, and insulin resistance in two populations with a high risk of type 2 diabetes mellitus

A total of 359 Wanigelas from Papua New Guinea and 1041 Nauruans had urinary albumin concentrations (UAC), serum insulin, and a number of cardiovascular disease (CVD) risk factors measured during population-based surveys of non-insulin-dependent diabetes mellitus. These data were used to explore the hypothesis that microalbuminuria is closely associated with insulin resistance and the metabolic syndrome. In both Nauruans and Wanigelas, worsening glucose tolerance was associated with increasing prevalence of micro- and macroalbuminuria. Within each category of glucose tolerance, microalbuminuria was associated with general worsening of cardiovascular risk factors including lipid concentrations, blood pressure and obesity, although few of the associations were statistically significant. Correlations between UAC and markers of insulin resistance (fasting insulin, fasting insulin/glucose ratio and HOMAS%, a computer-modelled estimate of insulin sensitivity) were weak and inconsistent irrespective of glucose tolerance status. Relationships between insulin sensitivity and urinary albumin in normoglycaemic Wanigelas and Nauruans, and in diabetic Nauruans, were no longer significant after adjusting for fasting glucose and body mass index. While microalbuminuria in Nauruans and Wanigelas was associated with cardiovascular risk factors irrespective of glucose tolerance, it seems unlikely on the basis of these results that the relationship is mediated through a common association with insulin resistance.

Relationship of insulin resistance to weight gain in nondiabetic Asian Indian, Creole, and Chinese Mauritians. Mauritius Non-communicable Disease Study Group

There is evidence from animal models that postprandial insulin hypersecretion may precede the development of obesity and insulin resistance, but it is not clear if this is the case in humans. Recently, two longitudinal studies have suggested that insulin resistance acts to limit further weight gain rather than to promote it. The relationship of markers of insulin sensitivity and secretion to changes in weight and the waist to hip ratio (WHR) was therefore examined in nondiabetic Asian Indian (n = 2,169), Creole (n = 798), and Chinese (n = 189) Mauritians over a 5-year follow-up period. Younger age and lower initial body mass index (BMI) were consistent independent predictors of increase in weight in all sex-ethnic subgroups, and older age, higher BMI, and lower WHR were associated with change in WHR. Insulin sensitivity was assessed by homeostatic model assessment (HOMAS), as well as by fasting insulin and the ratio of fasting insulin to glucose. Insulin resistance predicted weight gain in Chinese men independently of baseline age and BMI. In Asian Indian and Creole men and women, these correlations were in the opposite direction (ie, insulin sensitivity predicted weight gain) but became nonsignificant when age and BMI were controlled. There was little relationship of insulin resistance/sensitivity to the change in WHR once baseline BMI was controlled. These data provide suggestive but not convincing evidence that insulin resistance may limit weight gain, and contradictory evidence in one ethnic group that insulin resistance promotes weight gain.

A case-control study of diet in newly diagnosed NIDDM in the Wanigela people of Papua New Guinea

OBJECTIVE--To study the association between diet and newly diagnosed NIDDM in the Wanigela people of Papua New Guinea, a population with an extraordinary susceptibility for NIDDM. RESEARCH DESIGN AND METHODS--We performed a case-control study of Wanigela people from an urban settlement (Koki). Case patients (n = 145) were asymptomatic subjects in whom NIDDM was newly diagnosed using a 2-h 75-g oral glucose tolerance test. Control subjects with glucose tolerance (n = 140) were group-matched on the basis of age and sex. A detailed food frequency questionnaire was used to determine energy and nutrient intakes. Nutrient intakes were compared directly and after calculation of residuals to correct for energy intake. Odds ratios for NIDDM were computed in relation to total energy and specific nutrient intakes, adjusting for age, sex, BMI, waist-to-hip ratio, and physical activity. RESULTS--There were no differences between case patients and control subjects in mean values of total energy-adjusted nutrient intakes. In logistic regression models, neither total energy nor any specific nutrients were associated with increased risk of NIDDM. When models were repeated with nutrients categorized by textiles, there were marginally significant associations with intakes of fiber (positive) and cholesterol, protein, and sugar (negative). CONCLUSIONS--This study does not support the hypothesis that saturated fat is an independent risk factor for NIDDM. The weak associations of intakes of fiber and cholesterol with newly diagnosed NIDDM were in the opposite directions to those expected and are probably due to chance. Relative homogeneity of diet within a community, such as that found in Koki, makes it difficult to demonstrate risk factor-disease associations. However, changes in diet and reduced levels of physical activity accompanying urbanization undoubtedly contribute to the high prevalence of obesity observed in this community, and hence diet is likely to contribute to NIDDM risk at least by indirect means.

Mortality in Micronesian Nauruans and Melanesian and Indian Fijians is not associated with obesity

The association of obesity with mortality was investigated in population-based samples of Micronesian Nauruans (n = 1,400), Melanesian Fijians (n = 1,279), and Indian Fijians (n = 1,182), over 10 years from 1982 in Nauru, and 11 years from 1980 in Fiji. At the end of follow-up, vital status was known for all Nauruans and all but 3.5% of Fijians. Mortality rates were higher in Nauru than Fiji, and in Melanesians than Indians. The mean body mass index of decedents was similar to or less than (Nauruan men, p < 0.001) that of survivors in each sex-ethnic group. Crude mortality rates showed an inverse relation with body mass index in Nauruan men, with inconsistent relations in other sex-ethnic groups. After stratification by diabetes status, there was no relation between mortality and obesity in nondiabetic subjects, but an inverse relation was observed among diabetic subjects in each population. These findings persisted even after the exclusion of subjects who died within the first 2 years of follow-up. After controlling for age, smoking, and diabetes status in Cox proportional hazard models, body mass index (as a continuous variable) was not related to mortality in any sex/ethnic group and tended to be negatively associated with mortality risk. Interactions of body mass index with age, smoking, and diabetes status were not significant. Mortality risk was significantly increased in older subjects and in diabetic subjects, and cigarette smoking also increased risk in some groups. Stratification of analyses according to cigarette smoking did not alter the nature of the results. The association of mortality and body mass index categorized by quartiles was also investigated. After adjusting for age alone, or age, smoking, and diabetes status, the lower quartiles of body mass index were consistently associated with the highest relative risk for mortality. Quadratic terms for body mass index did not improve Cox models in subjects with normal glucose tolerance. Relations with cardiovascular disease mortality were also assessed and results were inconsistent, although positive trends were observed in Nauruan women (p = 0.02) and Melanesian men (p = 0.06). Overall, there was little evidence to suggest that obesity was a risk factor for total or cardiovascular mortality in these populations. However, obesity is clearly associated with a high risk of diabetes and other morbid conditions and at least on this basis it would seem desirable to prevent obesity in these and other Pacific populations.

Incidence, increasing prevalence, and predictors of change in obesity and fat distribution over 5 years in the rapidly developing population of Mauritius

OBJECTIVE

To investigate the incidence and trends in prevalence of obesity and adverse fat distribution in Mauritius over 5 years.

DESIGN

Prevalence studies were conducted in 1987 and 1992, incidence was estimated in a sub-sample of subjects attending on both occasions.

SUBJECTS

5021 Indian, Creole and Chinese Mauritian adults aged 25-74 were examined in 1987, in 1992 5111 subjects were examined, of whom 3667 had data from 1987.

MEASUREMENTS

Body mass index (BMI), waist-hip ratio (WHR) and 75g oral glucose tolerance test. Questionnaire data were collected on parity, physical activity, smoking, education and income.

RESULTS

The prevalence of 'overweight or obesity' (BMI > 25 kg/m2) increased from 26.1% to 35.7% in men and from 37.9% to 47.7% in women. The prevalence of abdominal obesity (WHR > 85 percentile in 1987 for each sex) also increased. The cumulative incidence of overweight or obesity in men ranged from 10.8% in Chinese to 18.2% in Creoles, and in women from 16.1% to 27.5% in Chinese and Creoles, respectively. The incidence of abdominal obesity exceeded 20% in Indian men and Indian and Creole women. Increases in BMI were predicted by younger age, leanness, non-diabetic glucose tolerance, smoking cessation (men) and multiparity and lower baseline income (women). Increases in WHR were predicted by ethnicity and BMI in men, and by glucose tolerance and BMI in women.

CONCLUSION

The increases in obesity observed in this study occurred despite concurrent national programs promoting a healthy diet and increased physical activity. This highlights the difficulty of reversing the adverse effects of lifestyle change in rapidly modernising populations.

Prevalence and secular trends in obesity in Pacific and Indian Ocean island populations

Surveys conducted in 10 Pacific island populations and in the multiethnic populations of Mauritius and Rodrigues in the Indian Ocean have provided data on the prevalence of obesity, potential etiological factors and medical hazards associated with obesity. The results indicate that the prevalence of obesity (by body mass index (BMI) in some of these populations is among the highest in the world. Obesity related to degree of modernization is more common in urban than in rural locations and tends to be found more often in women. In two populations where longitudinal data were available, there were dramatic increases in prevalence over relatively short time periods. Obesity contributed to the risk of non-insulin-dependent diabetes mellitus (NIDDM) and was associated with other risk factors for cardiovascular disease (CVD) in all populations, but no relationship could be found with total mortality in three ethnic groups for whom data were available. A genetic susceptibility to obesity combined with social pressures that favor high energy intakes and reduced physical activity are believed to be important in these populations. The challenge for the future lies in developing culturally appropriate programs for preventing obesity and thus reducing associated morbidity, while continuing to research its behavioral and genetic determinants.

Factors associated with impaired vibration perception in Mauritians with normal and abnormal glucose tolerance. Mauritius NCD Study Group

Vibration perception threshold (VPT) was measured in 1185 Indian, Creole, and Chinese men and women in Mauritius, where the current prevalence of diabetes mellitus in adults aged 25-74 years is estimated to be 13%. Vibration perception threshold was measured using a biothesiometer, at seven sites in the hand, wrist, foot, and ankle, during a population survey in 76% of 574 known diabetic patients (KDM), 79% of 525 newly diagnosed diabetic patients (NDM), 18% of 1121 subjects with impaired glucose tolerance (IGT), and in 127 normal subjects. The association of VPT with glucose tolerance and other risk factors was assessed in order to identify individuals most at risk of foot ulceration and to determine whether risk factors and normal levels for VPT in these ethnic groups were consistent with those reported for Caucasians. After adjusting for age and height, geometric mean VPT at six of seven sites increased significantly with worsening glucose tolerance and increasing duration of diabetes in both men and women, VPT also increased significantly with level of fasting plasma glucose in men, but not women. Smoking and alcohol consumption had no effect on VPT, and body-mass index (BMI) was positively associated only at some sites. Chinese subjects had lower VPTs than Indians or Creoles. In multiple linear regression models, age, male gender, duration of diabetes, ethnic group, and height (lower extremity sites) were significantly associated with VPT among diabetic subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Modernity and obesity in coastal and Highland Papua New Guinea

OBJECTIVE

To investigate the association between individual degree of modernization and obesity in Papua New Guineans using a score of relative 'modernity'.

DESIGN

Cross-sectional survey in six populations with varying degrees of modernity. Independent effects of modernity score, components of modernity score, age and physical activity were assessed in relation to general obesity (body mass index (BMI)) and body fat distribution (waist-hip ratio (WHR)). A sub-study of the relationship between diet and modernity was also performed.

SETTING

Population-based samples of subjects in three Highland and three coastal locations in the developing country of Papua New Guinea (PNG).

SUBJECTS

1877 subjects > or = 25 years of age attended the survey.

MEASUREMENTS

Age, physical activity, BMI, WHR, 2-h oral glucose tolerance test, and modernity score, based on area of origin, father's employment, type and duration of individual's employment, education, years in an urban centre, housing type and spouse score.

RESULTS

More modern subjects had higher mean BMI and lower levels of physical activity, and mean WHR also varied with modernity in men but not women. In linear regression analysis, total modernity score was significantly associated with both BMI and WHR in men and women, independently of age and physical activity. When components of the modernity score were examined, younger age, more sophisticated housing and increasing number of years in an urban centre were independently associated with BMI in men and women, while education level and reduced physical activity were also significant predictors in men. Associations with WHR were weaker. Results of the dietary sub-study suggested that the lowest energy and nutrient intakes occurred in the least modern men and women.

CONCLUSION

Aspects of modernity, such as more sophisticated housing and greater number of years spent in an urban centre, may be markers of higher income and increasing adoption of Western ways, which in turn are associated with physical inactivity and increased availability of energy-dense Western food, thus promoting obesity in this rapidly developing Pacific nation.

The epidemiology of obesity

Obesity and pattern of fat distribution are both important factors related to poor health outcomes. Many measures of obesity and fat distribution pattern have been employed by different authors and to facilitate interpopulation comparisons and interpretation of secular trends it is necessary that standardized methods for measurement and classification are set in place. The use of BMI as a measure of fatness for epidemiological studies is widely accepted, easily measured and BMI predicts morbidity and mortality in many populations. The most appropriate level at which to define obesity is a matter of debate but systems which use BMI > or = 25 and < or = 30 kg/m2 as overweight, and BMI > 30 kg/m2 as obese for all adults are simple, easily remembered, already widely used and BMIs above 30 kg/m2 are clearly associated with increased risk of morbidity and mortality. In some populations there may be a case for using a lower cut-off but not unless there is specific evidence to support this. For the present WHR is probably the best method for assessing fat distribution, although waist circumference on its own may be more useful in determining risk levels. Standard sites for measurement of both waist and hip girths have been described. There is a large variation in the prevalence of obesity across the populations for which data is available, with high prevalences of obesity and dramatic secular trends especially apparent in modernizing Pacific Island populations. The 'thrifty genotype' hypothesis has been invoked to try and explain this situation. The clustering of obesity, NIDDM and CVD risk factors has been recognized and various 'syndromes' have been described which group different factors together, with hyperinsulinaemia and insulin resistance proposed as the underlying problem.

Extraordinary prevalence of non-insulin-dependent diabetes mellitus and bimodal plasma glucose distribution in the Wanigela people of Papua New Guinea

OBJECTIVE

To determine the current prevalence of impaired glucose tolerance (IGT) and non-insulin-dependent diabetes mellitus (NIDDM) in Melanesians of three coastal Papua New Guinean communities, to relate this to previous studies, and to investigate plasma glucose distributions in these populations.

DESIGN

Cross-sectional survey, using 75 g oral glucose tolerance tests and World Health Organization criteria.

SETTING

Rural Papuan villages of Wanigela and Kalo, and Wanigela people of the urban squatter settlement of Koki, Port Moresby.

SUBJECTS

All adults aged 25 years or more living in the three communities were eligible, with response rates of 77.2% (Koki), 88.1% (Wanigela) and 72.5% (Kalo).

MAIN OUTCOME MEASURES

Prevalence of abnormal glucose tolerance, risk factor levels, fasting and two-hour plasma glucose concentration.

RESULTS

Age-standardised prevalence of NIDDM in Koki Wanigelas was 27.5% in men and 33.0% in women; an additional 20.5% of men and 22.0% of women had IGT. Even in the youngest age group (25-34 years), 36.5% of subjects had abnormal glucose tolerance. The overall prevalences of NIDDM and IGT in rural Wanigelas were 11.7% and 17.0% respectively. In Kalo both were uncommon. The prevalences of IGT and NIDDM in Koki had doubled over a 14-year period. The age-standardised prevalence of abnormal glucose tolerance in the Koki Wanigelas is the second highest in the world after the Arizona Pima Indians, and higher than in Micronesian Nauruans, even though the latter are more obese. Both fasting and two-hour glucose concentrations in all age groups in Koki were clearly bimodal, a mixture of two log-normal distributions.

CONCLUSIONS

The Wanigela people of Papua New Guinea have an extra-ordinary susceptibility to glucose intolerance which is exposed after adoption of modern lifestyle habits. A "founder effect" may explain the high frequency of a diabetogenic genotype in this population.

Dramatic increase in the prevalence of obesity in western Samoa over the 13 year period 1978-1991

Obesity and an increasing prevalence of associated conditions such as diabetes and cardiovascular disease are frequently observed in Pacific populations as lifestyles become more modernized. In 1978, a survey conducted in three geographically defined populations in Western Samoa showed large differences in the prevalence of obesity (body mass index (BMI) > or = 30 kg/m2) between rural and urban populations. A follow-up survey using similar methods was performed in 1991 to examine the current level of obesity in these three locations and to assess changes over time. Cross-sectional differences in the prevalence of obesity, mean BMI and waist-hip circumference ratio (WHR) between urban Apia and rural Poutasi and Tuasivi were examined after adjusting for age. There were higher levels of obesity in urban vs rural areas: 74% of women in Apia were obese compared with 62% in Poutasi and 56% in Tuasivi. In men, comparable figures were 57%, 44% and 36% for Apia, Poutasi and Tuasivi respectively. Mean BMIs followed the same pattern. By contrast, WHR varied little between locations. Even in subjects aged 25-34 years, more than 50% of women in all locations, and 45% of urban men were obese. Increasing physical activity in men, but not women, was associated with lower mean BMI. Increasing education level and job status were associated with increasing BMI but these relationships were significant only in men. Multivariate analysis showed age, location (urban), occupation (high status, women), and in men, physical inactivity, to be independently associated with increased risk of obesity. Prevalence of obesity increased dramatically between 1978 and 1991 in all locations, but especially in Tuasivi, where in males the increase was 297% and in females 115%. There was a rightward shift in the distribution of body mass index in both sexes and all locations. These extreme increases in the prevalence of obesity, even in young adults, over the relatively short 13-year study period suggest an increasing burden of chronic diseases facing Western Samoa in the future, and emphasize the need for effective intervention to bring about lifestyle modification.

Association of body mass index and waist-hip circumference ratio with cardiovascular disease risk factors in Micronesian Nauruans

The relationship of body mass index (BMI) and waist-hip circumference ratio (WHR) with cardiovascular disease (CVD) risk factors was examined in adult Nauruans, a population with a particularly high prevalence of non-insulin dependent diabetes mellitus and obesity, with mean BMI 34.2 kg/m2 in males and 34.9 kg/m2 in females aged > or = 20 years. In univariate analysis for men, fasting and 2 h insulin (after a 75 g glucose load), total cholesterol, high density lipoprotein (HDL)/total cholesterol ratio and uric acid levels varied significantly across tertiles of BMI but not WHR, while fasting and 2 h glucose and fasting triglyceride levels were significantly associated with both BMI and WHR. Neither systolic nor diastolic blood pressure were related to BMI tertiles, but diastolic blood pressure was associated with WHR. High density lipoprotein cholesterol was not associated with tertiles of BMI or WHR in men. In women, BMI and WHR had similar univariate associations. When the effects of BMI and WHR were studied simultaneously by analysis of covariance, adjusting for age, BMI explained more of the variance in risk factor levels in men than did WHR for fasting and 2 h insulin, total cholesterol, HDL cholesterol, HDL/total cholesterol ratio and uric acid, while in women, BMI was more important for 2 h insulin, 2 h glucose and uric acid, and equal with WHR for fasting insulin. Waist-hip circumference ratio was more important for fasting plasma glucose, fasting triglycerides and both systolic and diastolic blood pressure in men and women. There was little evidence for statistically important interaction between BMI and WHR in relation to risk factor levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Diet does not predict incidence or prevalence of non-insulin-dependent diabetes in Nauruans

Cross-sectional and longitudinal relationships between diet and non-insulin-dependent diabetes (NIDDM) were assessed in Nauruan adults to determine if a particular component of the diet contributed to the high prevalence of NIDDM in this population. In 1982, 24-h dietary recall data were collected from 430 Nauruans over the age of 20, who were participating in a noncommunicable disease (NCD) survey. In 1987 a follow-up survey was performed which included 350 of the subjects from whom dietary data was obtained. Neither cross-sectional nor longitudinal analyses showed any statistically significant associations between any of the specific dietary components studied and NIDDM prevalence or incidence. However, when nutrient intakes were adjusted for energy intake it appeared that the age- and body-mass-index (BMI)-corrected mean intakes of total fat, total carbohydrates, alcohol, sugar and monounsaturated fat were slightly higher in the seven incident cases than in those who remained healthy, while intakes of protein, fibre and cholesterol were lower. Despite the inability to demonstrate an association between NIDDM risk and nutrient intake at the individual level, Nauruans as a population have total energy intakes 115-135% greater than recommended for maintenance of healthy weight, protein intakes about 250% of that required, sugar intakes about twic 1000 e the recommended, fibre intakes only about 30% of current recommended levels and in men a mean alcohol intake more than three times the recommended level. This adverse diet undoubtedly contributes to the high prevalence of obesity in the population and hence, even if there are no direct dietary effects, to the risk of NIDDM and other diet-related diseases.

Abnormal glucose tolerance and alcohol consumption in three populations at high risk of non-insulin-dependent diabetes mellitus

The associations of alcohol intake with the prevalence and incidence of non-insulin-dependent diabetes mellitus (NIDDM) and impaired glucose tolerance were examined in three populations at high risk for NIDDM. Population-based surveys performed in Mauritius in 1987, in Kiribati in 1981, and in Nauru in 1982 and 1987 provided data on alcohol intake, glucose tolerance, and associated risk factors for NIDDM in over 8,700 subjects not previously known to be diabetic. There was no consistent relation of alcohol intake to fasting or 2-hour glucose concentration in either prevalence or prospective studies. Odds ratios for newly diagnosed NIDDM associated with increasing alcohol intake were not significantly different from unity in any population in either prevalence or prospective data. Alcohol consumption was, however, related to other metabolic parameters associated with cardiovascular disease and NIDDM, i.e., increased systolic blood pressure, fasting triglycerides, uric acid, and high density lipoprotein cholesterol and a reduction in 2-hour insulin. The results of this study do not support the hypothesis of an independent effect of alcohol consumption on the development of NIDDM, but increased alcohol consumption is associated with variation in other cardiovascular disease risk factors in these three populations.