Verification of measles elimination in Australia: Application of World Health Organization regional guidelines

Background: The World Health Organization (WHO) Western Pacific Region (WPR) Guidelines on verification of measles elimination were established in 2012. This article outlines Australia’s approach to addressing the guideline’s five lines of evidence, which led to formal verification of elimination by the WHO Regional Verification Commission (RVC) in March 2014.

Methods: The criteria were addressed using national measles notifications, data from selected laboratories, the national childhood immunization register, and three national serosurveys (1998/1999, 2002, 2007).

Results: Australia met or exceeded all indicator targets with either national or sentinel data. Laboratory and epidemiological surveillance were of high quality, with 85% of cases documented as imported/import-related (target 80%); coverage with the first dose of measles vaccine was close to 94% in 2008–2012 and second dose coverage increased to 91% in 2012 (target >95%). There is ongoing commitment by the Australian Government to increase immunization coverage, and the absence of sustained transmission of any single measles genotype was demonstrated.

Conclusions: This is the first documentation of the successful application of the WPR RVC guidelines. The indicators afford some flexibility but appear to provide appropriate rigor to judge achievement of measles elimination. Our experience could assist other countries seeking to verify their elimination status.

EbolaTracks: an automated SMS system for monitoring persons potentially exposed to Ebola virus disease

We report development and implementation of a short message service (SMS)-based system to facilitate active monitoring of persons potentially exposed to Ebola virus disease (EVD), whether returning from EVD-affected countries, or contacts of local cases, should they occur. The system solicits information on symptoms and temperature twice daily. We demonstrated proof-of-concept; however this system would likely be even more useful where there are many local contacts to confirmed EVD cases or travellers from EVD-affected countries.

Epidemiological study of severe febrile reactions in young children in Western Australia caused by a 2010 trivalent inactivated influenza vaccine

BACKGROUND

The 2010 influenza vaccination program for children aged 6 months to 4 years in Western Australia (WA) was suspended following reports of severe febrile reactions, including febrile convulsions, following vaccination with trivalent inactivated influenza vaccine (TIV).

METHODS

To investigate the association between severe febrile reactions and TIV, three studies were conducted: (i) rates of febrile convulsions within 72 h of receiving TIV in 2010 were estimated by vaccine formulation and batch; (ii) numbers of children presenting to hospital emergency departments with febrile convulsions from 2008 to 2010 were compared; and (iii) a retrospective cohort study of 360 children was conducted to compare the reactogenicity of available TIV formulations.

FINDINGS

In 2010, an estimated maximum of 18,816 doses of TIV were administered and 63 febrile convulsions were recorded, giving an estimated rate of 3.3 (95% CI 2.6 to 4.2) per 1000 doses of TIV administered. The odds of a TIV-associated febrile convulsion was highly elevated in 2010 (p<0.001) and was associated with the vaccine formulations of one manufacturer-Fluvax and Fluvax Junior (CSL Biotherapies). The risk of both febrile convulsions (p<0.0001) and other febrile reactions (p<0.0001) was significantly greater for Fluvax formulations compared to the major alternate brand. The risk of febrile events was not associated with prior receipt of TIV or monovalent 2009 H1N1 pandemic vaccine. The biological cause of the febrile reactions is currently unknown.

INTERPRETATION

One brand of influenza vaccine was responsible for the increase in febrile reactions, including febrile convulsions. Until the biological reason for this is determined and remediation undertaken, childhood influenza vaccination programs should not include Fluvax-type formulations and enhanced surveillance for febrile reactions in children receiving TIV should be undertaken.

Secondary attack rate of pandemic influenza A(H1N1)2009 in Western Australian households, 29 May–7 August 2009

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Secondary attack rate of pandemic influenza A(H1N1) 2009 in Western Australian households, 29 May-7 August 2009

Understanding household transmission of the pandemic influenza A(H1N1)2009 virus, including risk factors for transmission, is important for refining public health strategies to reduce the burden of the disease. During the influenza season of 2009 we investigated transmission of the emerging virus in 595 households in which the index case was the first symptomatic case of influenza A(H1N1)2009. Secondary cases were defined as household contacts with influenza-like illness (ILI) or laboratory-confirmed influenza A(H1N1)2009, occurring at least one day after but within seven days following symptom onset in the index case. ILI developed in 231 of the 1,589 household contacts, a secondary attack rate of 14.5% (95% confidence interval (CI): 12.9–16.4). At least one secondary case occurred in 166 of the 595 households (a household transmission rate of 27.9%; 95% CI: 24.5–31.6).Of these, 127 (76.5%) households reported one secondary case and 39 (23.5%) households reported two or more secondary cases. Secondary attack rates were highest in children younger than five years (p=0.001), and young children were also more efficient transmitters (p=0.01). Individual risk was not associated with household size. Prophylactic antiviral therapy was associated with reduced transmission (p=0.03). The secondary attack rate of ILI in households with a confirmed pandemic influenza A(H1N1)2009 index case was comparable to that described previously for seasonal influenza.

Association between 2009 seasonal influenza vaccine and influenza-like illness during the 2009 pandemic: preliminary results of a large household transmission study in Western Australia

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Association between 2009 seasonal influenza vaccine and influenza-like illness during the 2009 pandemic: preliminary results of a large household transmission study in Western Australia

We conducted a prospective household transmission study to examine whether receipt of 2009 trivalent influenza vaccine (TIV) was associated with increased risk of influenza-like illness (ILI) among contacts of confirmed pandemic influenza A(H1N1) 2009 patients. In the week following onset of pandemic illness in a household member, 46 (15%) of 304 TIV-vaccinated contacts, and 174 (15%) of 1,162 unvaccinated contacts developed ILI (p=0.95). Receipt of 2009 TIV had no effect on one's risk of pandemic illness.

Increasing prevalence of Type 2 diabetes mellitus in all ethnic groups in Mauritius

AIMS

To describe the prevalence of different stages of glucose intolerance in a population from Mauritius followed over 11 years.

METHODS

Population-based surveys were undertaken in the multiethnic nation of Mauritius in 1987, 1992 and 1998, with 5083, 6616, and 6291 participants, respectively. Questionnaires, anthropometric measurements, and a 2-h 75-g oral glucose tolerance test were included. Subjects aged between 25 and 75 years with classifiable data were identified; 4991, 6463 and 5392 from 1987, 1992 and 1998, respectively. Glucose tolerance was classified according to WHO 1999 criteria.

RESULTS

The prevalence of Type 2 diabetes increased significantly during the period studied, from 12.8% in 1987, to 15.2% in 1992, and 17.9% in 1998. The increasing prevalence was seen in both men and women, and in all age groups. The prevalence of known diabetes (KDM) increased progressively, and more markedly than the increase in newly diagnosed diabetes (NDM). A diagnosis of impaired glucose tolerance (IGT) was more prevalent amongst women whereas impaired fasting glucose (IFG) was more common amongst men. The prevalences of IGT and IFG did not change markedly during the period. The prevalence of diabetes and IGT was similar for participants of Indian, Creole and Chinese background in each survey, and the increasing prevalence of diabetes was seen in all ethnic groups.

CONCLUSION

In this study, we report an increasing prevalence of diabetes over an 11-year period in Mauritius. This increase was seen in both sexes, and in all age and ethnic groups, and was mainly due to an increase in the numbers of those with known diabetes.

High incidence of type 2 diabetes and increasing conversion rates from impaired fasting glucose and impaired glucose tolerance to diabetes in Mauritius

OBJECTIVE

To describe the incidence of different stages of glucose intolerance in a population from Mauritius followed over 11 years. RESEARCH DESIGN, METHODS AND SUBJECTS: Population-based surveys were undertaken in the multi-ethnic nation of Mauritius in 1987, 1992 and 1998 with 5083, 6616 and 6291 participants, respectively. Questionnaires, anthropometric measurements, and a 2-h 75-g oral glucose tolerance test were included. Three cohorts aged between 25 and 79 years with classifiable glucose tolerance data were identified; 3680 between 1987 and 1992, 4178 between 1992 and 1998, and 2631 between 1987 and 1998. Glucose tolerance was classified according to WHO 1999 criteria.

RESULTS

The incidence rate of type 2 diabetes was higher between 1992 and 1998 than between 1987 and 1992. In men, the incidence was similar between cohorts (24.5 and 25.4 per 1000 person-years) whereas the incidence increased in women (23.3 and 16.4 per 1000 person-years). The incidence of diabetes peaked in the 45-54 year age group and then plateaued or fell. The incidences of impaired glucose tolerance (IGT) and impaired fasting glucose (IFG) decreased in both men and women. Of normoglycaemic subjects at baseline, more women than men developed IGT and more men than women developed IFG. Of those labelled as IFG in 1987, 38% developed diabetes after 11 years. The corresponding figure for IGT was 46%.

CONCLUSIONS

In this study, we report changes in incidence rates of glucose intolerance over a 11-year period. In particular, differences between men and women were observed. The increased incidence of IGT in women compared with men, and increased incidence of IFG in men compared with women was consistent with, and explains the sex biases seen in the prevalences of these states.

Murray Valley encephalitis in Western Australia in 2000, with evidence of southerly spread

We describe the epidemiological and clinical features of human Murray Valley encephalitis (MVE) and Kunjin (KUN) virus infections in Western Australia (WA) during March to July 2000. A case series was performed. For laboratory-confirmed cases, travel histories and clinical details were collected from patients, family members, friends or treating physicians. Surveillance data from the sentinel chicken program and climatic conditions were reviewed. Nine encephalitic cases of MVE were recorded. Eight were non-Aboriginal adults (age range, 25 to 79 years; 5 male, 3 female) and 1 was an Aboriginal boy. Four cases acquired infection in the Murchison and Midwest regions of WA from which no human cases of MVE have been reported previously. One of the 9 cases was fatal and 3 had severe neurological sequelae. Five non-encephalitic infections were also recorded, 3 MVE and 2 KUN. Encephalitis caused by MVE virus remains a serious problem with no improvement in clinical outcomes in the last 25 years. Excessive rainfall with widespread flooding in the northern two-thirds of WA provided ideal conditions for mosquito breeding and favoured southerly spread of the virus into new and more heavily populated areas. Surveillance in WA with sentinel chickens and mosquito trapping needs expansion to define the boundaries of MVE virus activity. To enable timely warnings to the public, and to institute mosquito control where feasible, continued surveillance in all Australian areas at risk is indicated.

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.

Impaired fasting glucose or impaired glucose tolerance. What best predicts future diabetes in Mauritius?

OBJECTIVE

To determine if impaired fasting glucose (IFG; fasting plasma glucose level 6.1-6.9 mmol/l) can predict future type 2 diabetes as accurately as does impaired glucose tolerance (IGT; 2-h plasma glucose level 7.8-11.0 mmol/l).

RESEARCH DESIGN AND METHODS

A longitudinal population-based study was performed with surveys in 1987 and 1992 on the island of Mauritius, assessing diabetes status by the oral glucose tolerance test. A total of 3,717 subjects took part in both surveys. Of these subjects, 3,229 were not diabetic in 1987 and formed the basis of this study.

RESULTS

At baseline, there were 607 subjects with IGT and 266 subjects with IFG. There were 297 subjects who developed diabetes by 1992. For predicting progression to type 2 diabetes, the sensitivity, specificity, and positive predictive values were 26, 94, and 29% for IFG and 50, 84, and 24% for IGT, respectively. Only 26% of subjects that progressed to type 2 diabetes were predicted by their IFG values, but a further 35% could be identified by also considering IGT. The sensitivities were 24% for IFG and 37% for IGT in men and 26% for IFG and 66% for IGT in women, respectively.

CONCLUSIONS

These data demonstrate the higher sensitivity of IGT over IFG for predicting progression to type 2 diabetes. Screening by the criteria for IFG alone would identify fewer people who subsequently progress to type 2 diabetes than would the oral glucose tolerance test.

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.

Occupational status and cardiovascular disease risk factors in the rapidly developing, high-risk population of Mauritius

This study examined the relation between occupation and cardiovascular disease (CVD) risk factors in 2,795 individuals between ages 35 and 54 years from the rapidly developing island nation of Mauritius. Participants attended a 1992 population-based survey of noncommunicable disease (89.1 % response rate). Occupational status, physical activity in the previous year, cigarette smoking, and alcohol consumption were assessed by questionnaire. Anthropometric and metabolic measures included body mass index (kg/m2),waist-to-hip ratio, fasting serum high density lipoprotein cholesterol and low density lipoprotein cholesterol (LDL cholesterol), triglycerides, 2-hour postload plasma glucose and serum insulin concentrations, and blood pressure. In comparison with professional/skilled workers, age-adjusted means of insulin and glucose, LDL cholesterol, triglycerides, and systolic and diastolic blood pressures were significantly (p < 0.05) lower, and the age-adjusted mean for high density lipoprotein cholesterol was significantly higher for unskilled men. In women, risk factors other than LDL cholesterol varied significantly (p < 0.05) across occupational categories, with homemakers tending to have the least favorable profile. Unskilled workers reported significantly more physical activity (p < 0.01), alcohol consumption, and cigarette smoking (men only) (p < 0.05) than did the other groups. Adjustment for multiple covariates revealed an independent association between occupational status and most CVD risk factors, with physical activity attenuating this association. These results elucidate mediating behaviors of CVD risk across occupational categories that could be applied to intervention strategies in Mauritius.

Prevalence and risk factors for diabetic retinopathy in the multiethnic population of Mauritius

This study examines the prevalence of, and risk factors for, diabetic retinopathy in Asian Indian, Chinese, and Creole Mauritians in whom there is an increasing prevalence of non-insulin-dependent diabetes mellitus (NIDDM). As part of a population-based survey on the Indian Ocean island of Mauritius in 1992, glucose tolerance was classified using a 75-g oral glucose tolerance test on 6,553 persons. Subjects with newly diagnosed (n = 358) or known diabetes (n = 388), and a random sample of one in four subjects with impaired glucose tolerance (n = 165), had stereoscopic 45 degrees retinal photographs taken of three fields in the right eye after mydriasis. Photographs were graded according to a modified version of the Airlie House criteria. The prevalence of nonproliferative and proliferative retinopathy was: 14.5% and 0.3%, respectively, in newly diagnosed diabetic subjects; 42.0% and 2.3%, respectively, in known diabetic subjects; and 9.1% and 0%, respectively, in persons with impaired glucose tolerance. Muslim Indians had the lowest prevalence of retinopathy (10.8% and 34.0% for new and known diabetes, respectively), but after adjusting for other factors, this was significantly different only to Creoles (18.8% and 53.8%, respectively). Univariate analysis revealed significant differences between diabetic subjects with and without retinopathy in mean age, body mass index, fasting and 2-hour plasma glucose levels, systolic and diastolic blood pressure, fasting triglycerides, serum creatinine, and urinary albumin levels. For known diabetes, mean duration of diabetes and the proportion using insulin were also greater in those with retinopathy. Multivariate analysis using logistic regression confirmed that increasing duration of diabetes, fasting plasma glucose, systolic blood pressure, and urinary albumin concentration, and decreasing body mass index, were independently associated with retinopathy. The high prevalence of diabetic retinopathy observed in all major ethnic groups in Mauritius portends a serious public health problem, given the relative recency of the NIDDM epidemic in that country and the limited resources for laser photocoagulation. Strategies to minimize this problem among those already known to have diabetes should include strict control of plasma glucose and blood pressure.

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.

Predictors of progression from impaired glucose tolerance to NIDDM: an analysis of six prospective studies

Risk factors associated with the progression from impaired glucose tolerance (IGT) to NIDDM were examined in data from six prospective studies. IGT and NIDDM were defined in all studies by World Health Organization (WHO) criteria, and baseline risk factors were measured at the time of first recognition of IGT. The studies varied in size from 177 to 693 participants with IGT, and included men and women followed from 2 to 27 years after the recognition of IGT. Across the six studies, the incidence rate of NIDDM was 57.2/1,000 person-years and ranged from 35.8/1,000 to 87.3/1,000 person-years. Although baseline measures of fasting and 2-h postchallenge glucose levels were both positively associated with NIDDM incidence, incidence rates were sharply higher for those in the top quartile of fasting plasma glucose levels, but increased linearly with increasing 2-h postchallenge glucose quartiles. Incidence rates were higher among the Hispanic, Mexican-American, Pima, and Nauruan populations than among Caucasians. The effect of baseline age on NIDDM incidence rates differed among the studies; the rates did not increase or rose only slightly with increasing baseline age in three of the studies and formed an inverted U in three studies. In all studies, estimates of obesity (including BMI, waist-to-hip ratio, and waist circumference) were positively associated with NIDDM incidence. BMI was associated with NIDDM incidence independently of fasting and 2-h post challenge glucose levels in the combined analysis of all six studies and in three cohorts separately, but not in the three studies with the highest NIDDM incidence rates. Sex and family history of diabetes were generally not related to NIDDM progression. This analysis indicates that persons with IGT are at high risk and that further refinement of risk can be made by other simple measurements. The ability to identify persons at high risk of NIDDM should facilitate clinical trials in diabetes prevention.

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.

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.

Insulin levels and the natural history of glucose intolerance in Nauruans

Longitudinal changes in serum insulin concentrations in relation to the natural history of glucose intolerance and factors associated with the incidence of NIDDM were studied in 838 nondiabetic Micronesian Nauruans over the 5.1-year period from 1982 to 1987. In 13 individuals who had data at three time-points and who developed NIDDM only at the final test, 2-h insulin levels followed an inverted V-shaped pattern as glucose tolerance declined to NIDDM. Subjects who were normal (n = 651) or had impaired glucose tolerance (IGT) (n = 187) at the 1982 baseline survey were divided into six natural history categories depending on glucose tolerance in 1987. Changes in glucose tolerance were accompanied by changes in mean 2-h insulin concentration that paralleled the inverted V pattern seen in the 13 individuals. Longitudinal changes in fasting insulin were less consistent, but mean levels increased as subjects developed NIDDM. The 5.1-year incidence of NIDDM was strongly related to baseline fasting and 2-h glucose concentrations, but associations with insulin levels were weak and inconsistent. Neither fasting nor 2-h insulin concentrations contributed to logistic regression models predicting deterioration in glucose tolerance, whereas fasting and 2-h glucose levels were included in all models and BMI also predicted deterioration from normal. These data showing sequential changes in insulin concentrations support the beta-cell exhaustion theory of NIDDM pathogenesis. However, in contrast to glucose concentrations and obesity, insulin levels are poor predictors of NIDDM risk in Nauruans. This reflects the complexity of interactions with other metabolic markers and the inability of a single examination to characterize the point along the inverted V curve of insulin secretion that an individual has reached.

Incidence of NIDDM and the natural history of IGT in Pacific and Indian Ocean populations

The prevalence of both NIDDM and IGT vary considerably within and between developing island populations of the Pacific and Indian Ocean regions. Longitudinal data have been collected recently in a number of these populations, allowing incidence rates to be compared. The incidence of NIDDM in adults ranged from a low of 1.2/1000 person-years (p.y.) in peri-urban and rural Papua New Guinea (PNG) Highlanders to 22.5/1000 p.y. in Micronesian Nauruans and 24.0/1000 p.y. in the rural Wanigelas of coastal PNG. Intermediate rates were observed in Polynesian Western Samoans (16.6 and 5.7/1000 p.y. in urban and rural areas, respectively) and ethnically diverse Mauritians: Asian Indians (15.8), African-origin Creoles (12.2), and Chinese (10.4/1000 p.y.). When stratified by age and body mass index (BMI), incidence in Wanigelas exceeded rates observed in Pima Indians, and rates in Mauritians were higher than those of Nauruans. For subjects with IGT at baseline, rates of conversion to NIDDM ranged from 19.0 to 102.6/1000 p.y. Particularly after stratifying for age and body mass index, it was apparent that there was less variation between populations in rates of decompensation from IGT than was observed for total incidence. The relative risk of conversion to NIDDM for IGT versus normal subjects ranged from 2.1 in urban Samoans to 7.6 in Nauruans, but most estimates exceeded 5.

Diabetes and nontraumatic lower extremity amputations. Incidence, risk factors, and prevention--a 12-year follow-up study in Nauru

OBJECTIVE

To measure the 12-year incidence (1982-1994) of nontraumatic lower extremity amputations (LEAs) in Nauruans, a population at high risk for NIDDM, and to determine the risk factors for amputation in Nauruans with diabetes.

RESEARCH DESIGN AND METHODS

Amputation data were abstracted from operating theater records in Nauru, hospital databases in Australia, and Nauru government records. Baseline characteristics of a cohort of 1,564 Nauruans aged > or = 20 years examined during a population-based survey in 1982 were used to determine risk factors for first LEAs.

RESULTS

Over this 12-year period, 46 first LEAs were performed on people with NIDDM, of whom 30 were members of the 1982 study cohort. The incidence of first LEAs in Nauruans aged > or = 25 years with NIDDM was 8.1 per 1,000 person-years in the study cohort and an estimated 7.6 per 1,000 person-years nationally. Amputations were associated significantly with lower BMI, lower blood pressure, higher fasting plasma glucose (FPG) level, and longer mean duration of diabetes at baseline, but levels of other risk factors, including cigarette smoking, plasma triglycerides, and plasma cholesterol, were also elevated in amputees. There were no amputations among individuals with baseline FPG levels < 7.8 mmol/l, irrespective of diabetes duration. FPG, baseline diabetes duration, and male sex were independent risk factors for first amputation using the Cox proportional hazards model. There was a decrease in the incidence of amputations after the commencement of a national foot care health education and prevention campaign in June 1992.

CONCLUSIONS

The incidence of LEAs in diabetic Nauruans was higher than in other populations after adjusting for age and duration. Given the apparent success of the Nauruan footcare program in reducing amputation rates, other populations with high rates of NIDDM and LEAs should consider population-wide prevention strategies.

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.

High mortality from cardiovascular disease and analysis of risk factors in Indian and Melanesian Fijians

BACKGROUND

In recent years, developing populations such as the Pacific island nation of Fiji, have seen decreases in infectious diseases and increasing frequency of cardiovascular diseases (CVD), diabetes and cancer. However, cohort studies of mortality in these populations are scarce. Here we report 11-year all-cause and cause-specific mortality rates and risk factors for total, CVD and coronary heart disease (CHD) for indigenous Melanesian and Asian Indian people of Fiji.

METHODS

Following a baseline risk factor survey in 1980, mortality surveillance continue until 1991 in a representative cohort of 1325 Melanesians and 1221 Indians from urban and rural areas of Fiji. Date and cause of death were recorded and total, CVD and CHD mortality rates calculated. Baseline predictors of mortality were assessed using Cox regression.

RESULTS

Total mortality rates in Melanesians were 15.9 and 9.2/1000 person-years, and in Indians were 13.5 and 6.8/1000 person-years, in men and women respectively. Death due to CHD was more common in men than women, and in Indian than Melanesian men, although total CVD deaths were more common in Melanesian men. Deaths due to CHD were more common in the urban than the rural area. After adjusting for other risk factors Indian ethnicity was associated with a significantly reduced risk of total and CVD mortality in men, and total mortality in women. Age and systolic blood pressure were consistently and independently associated with mortality from all causes, as well as CVD and CHD (except in Indian women). In men associations were also identified for total cholesterol with CVD and CHD mortality in Melanesians, and 2-hour plasma glucose with total and CVD mortality in Indians. In women, 2-hour glucose was important for total, CVD and CHD mortality in both ethnic groups as was smoking in Indians. Obesity had inconsistent associations with mortality.

CONCLUSION

Cardiovascular disease is now responsible for a large proportion of total mortality in both Indian and Melanesian Fijians. The major risk factors identified in Fijians are similar to those observed in developed populations.

Non-insulin-dependent diabetes and 11-year mortality in Asian Indian and Melanesian Fijians

This study reports 11-year all-cause and cause-specific mortality rates according to baseline glucose tolerance for a population-based sample of adult Melanesian and Indian Fijians (n = 2638), first surveyed in 1980. Risk factors for all-cause and cardiovascular disease (CVD) mortality in subjects with non-insulin-dependent diabetes (NIDDM) are also described. The baseline survey included 75 g oral glucose tolerance tests, measurements of blood pressure, body mass index, and triceps skinfold, assays of plasma cholesterol and triglycerides, electrocardiograms, and details of smoking habits and physical activity. Mortality status was ascertained for 2546 subjects through surveillance of death certificates, medical records and interview of subjects (or relatives). Mortality rates were increased in diabetic men and women of both ethnic groups: relative risks compared to subjects without diabetes at baseline were 1.7 (CI:0.9-3.1) and 2.0 (1.1-3.7) in Melanesian and 4.2 (2.7-6.5), 3.2 (1.9-5.7) in Indian men and women, respectively. A large proportion of mortality among diabetic subjects was attributed to CVD (62%, 66% in Melanesian and 54%, 58% in Indian men and women, respectively). Mortality rates tended to be higher in Melanesians than Indians, except for diabetic men where Indians had higher total and cardiovascular disease rates. In contrast to non-diabetic Fijians, diabetic women of both ethnic groups lost their relative protection from coronary heart disease (CHD). Cox regressions for diabetic subjects showed age and fasting plasma glucose to be independent predictors of all-cause mortality in men, and age, body mass index (inversely) and systolic blood pressure in women, but lipid concentrations, and cigarette smoking were not related. After accounting for conventional CVD risk factors, diabetes conferred significantly increased risk of total, CVD, and CHD mortality. The mortality experience of Melanesian and Indian Fijians with NIDDM is similar to that documented in developed populations, with excess mortality due to cardiovascular causes.

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.

Physical inactivity and glucose intolerance in the multiethnic island of Mauritius

The island nation of Mauritius, located in the southwest Indian Ocean, has a high prevalence of non-insulin-dependent diabetes mellitus (NIDDM) among all of its ethnic groups (Hindu and Muslim Indians, African-origin Creoles, and Chinese). These high rates of NIDDM among groups of varying genetic background provide strong support for the importance of environmental components in the etiology of the disease. Research in Mauritius using a simple activity scale has suggested that physical inactivity may be one of these components. The current investigation further examined the association between glucose tolerance and physical activity in middle-aged nondiabetic residents of Mauritius using a more extensive physical activity questionnaire (the Modifiable Activity Questionnaire). Excluding individuals with NIDDM, a statistically significant (P < 0.05) inverse relationship between physical activity and 2-h post-load glucose concentration was found for both males (rho = -0.14) and females (rho = -0.11). Stratifying by ethnic group, similar inverse correlations were observed in Hindu, Creole, and Chinese males, and in Hindu females (P < 0.05), as well as weaker relationships in Muslim males and Creole females (P < 0.10). Total physical activity remained an independent predictor of 2-h post-load glucose concentration after controlling for body mass index, waist-hip ratio, age, and family history of NIDDM. These data are supportive of a potentially important role of physical activity in the prevention of NIDDM in middle-aged inhabitants of Mauritius.

Changes in population cholesterol concentrations and other cardiovascular risk factor levels after five years of the non-communicable disease intervention programme in Mauritius. Mauritius Non-communicable Disease Study Group

OBJECTIVE

To study changes in the prevalence of risk factors for cardiovascular disease after a five year population-wide intervention programme promoting a healthy lifestyle in a developing country.

DESIGN

Cross sectional cluster surveys in 1987 and 1992. Methodology included a two hour 75 g oral glucose tolerance test, measurement of body mass index, waist:hip ratio, basal lipid concentrations, and blood pressure; and a lifestyle questionnaire.

SETTING

Mauritius, in the Indian Ocean.

SUBJECTS

All adults aged 25-74 years residing in geographically defined clusters.

MAIN OUTCOME MEASURES

Age standardised prevalence of categorical disease and risk factor conditions and mean levels and frequency distributions of continuous variables.

RESULTS

Response rates were 86.2% (5080/5892) in 1987 and 89.5% (5162/5770) in 1992. Significant decreases were found in the prevalence of hypertension (15.0% to 12.1% in men and 12.4% to 10.9% in women); cigarette smoking (58.2% to 47.2% and 6.9% to 3.7% respectively); and heavy alcohol consumption (38.2% to 14.4% and 2.6% to 0.6% respectively). Moderate leisure physical activity increased from 16.9% to 22.1% in men and from 1.3% to 2.7% in women. Mean population serum total cholesterol concentration fell appreciably from 5.5 mmol/l to 4.7 mmol/l (P < 0.001). The prevalence of overweight or obesity increased, and the rates of glucose intolerance changed little. The population frequency distributions of blood pressure, serum lipid concentration, and a composite risk factor score shifted advantageously.

CONCLUSIONS

Lifestyle intervention projects can be implemented and have positive effects in developing countries. A pronounced improvement in the population lipid profile in Mauritius was probably related to a change in the saturated fat content of a widely used cooking oil.

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.

High prevalence of diabetic retinopathy and nephropathy in Polynesians of Western Samoa

OBJECTIVE

To determine the prevalence of diabetic retinopathy and nephropathy retinopathy and nephropathy and to define associated risk factors in Polynesian Western Samoans with non-insulin-dependent diabetes mellitus (NIDDM) or impaired glucose tolerance (IGT).

RESEARCH DESIGN AND METHODS

A 1991 population-based study in Samoan adults (ages 25-74 years) included a 75-g oral glucose tolerance test, anthropometric measurements, and blood pressure recordings. Subjects with NIDDM or IGT had 45-degree stereo photographs taken (n = 263) (three standard fields of the right eye), and retinopathy was graded in comparison with Airlie House photographs. First-morning urine samples (n = 304) were also collected from these subjects and from a subsample with normal glucose tolerance. Urinary albumin concentration (UAC) was measured by radioimmunoassay: microalbuminuria was defined as UAC of 30-299 micrograms/ml; and macroalbuminuria among subjects with Proliferative diabetic retinopathy was found in 4.5% of known diabetic subjects. The prevalence of elevated UAC was 15.0% in subjects with IGT, 26.0% in newly diagnosed diabetes subjects, and 23.4% in known diabetes subjects. For all diabetic subjects (n = 162), the factors independently associated with diabetic retinopathy (logistic regression) were duration of diabetes, fasting plasma glucose, and body mass index (inversely). Duration of diabetes, serum triglyceride concentrations, and systolic blood pressure were independently associated with elevated UAC in all diabetic subjects (n = 138), and fasting plasma glucose had borderline significance.

CONCLUSIONS

Diabetic retinopathy and albuminuria are common in Polynesian Western Samoans. Duration of diabetes and level of glycemia were the most important associated factors. These data underline the need for cost-effective programs for the detection and early treatment of diabetes in Western Samoa and other developing populations with high susceptibility to NIDDM.

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.

Lack of antibodies to glutamic acid decarboxylase in young adults of the high diabetes prevalence Wanigela people of Papua New Guinea

Antibodies to glutamic acid decarboxylase (anti-GAD) are common in typical insulin-dependent diabetes mellitus, and also identify a sub-group of older persons who are originally misdiagnosed as having non-insulin-dependent disease (NIDDM). The Wanigela people of Papua New Guinea are highly susceptible to diabetes mellitus, with a prevalence of 20.4% in urbanised young adults aged 25-34 years. On the basis of clinical features including the presence of obesity and relatively high insulin concentrations the Wanigelas have NIDDM. To determine whether anti-GAD is present in this high prevalence form of diabetes, and to investigate whether there might be an autoimmune component to the disease, we measured anti-GAD in 93 newly-diagnosed diabetic subjects aged 25-44 years, and in 40 controls with normal glucose tolerance. There was no difference in mean levels of anti-GAD in diabetic subjects and normal controls. Two subjects had borderline elevated anti-GAD levels: one was a normal control, and the other a diabetic. This study shows that anti-GAD is not present in this (and probably other) high prevalence variant of NIDDM. Moreover, the results suggest strongly that diabetes in the Wanigela people is unlikely to have an autoimmune component to its pathogenesis.

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.

Is hyperinsulinaemia a central characteristic of a chronic cardiovascular risk factor clustering syndrome? Mixed findings in Asian Indian, Creole and Chinese Mauritians. Mauritius Noncommunicable Disease Study Group

The aim of the study was to investigate whether the constellation of cardiovascular disease risk factors, described as Insulin Resistance Syndrome, exists in the multi-ethnic population of Mauritius, and to assess whether hyperinsulinaemia is the key feature of this syndrome. A sample of 5080 Mauritian subjects (aged 25-74 years) was examined in a noncommunicable diseases survey in 1987. Survey procedure included an oral glucose tolerance test, and anthropometric, blood pressure, plasma lipids and serum insulin measurements. Abnormal glucose tolerance (diabetes and impaired glucose tolerance), general obesity, upper-body obesity, hypertension, low HDL-cholesterol, and hypertriglyceridaemia were defined as risk factor conditions. Mean values for a series of risk factor variables were compared between reference subjects (no risk factors) and those with a risk factor condition (either one condition only, or in combination with one or more others). Prevalence estimates for each risk factor condition in combination with three or more other conditions were three to four times greater than expected by chance, and levels of risk factors for subjects with more than one risk factor condition were further away from the reference levels than for those with just one condition. Fasting and 2-h serum insulin levels were elevated for each condition when in combination with others, or to a lesser extent when isolated. However, this was not the case for isolated hypertension where insulin levels were not elevated. When adjusted for age, sex, and body mass index, insulin levels were only significantly elevated in subjects with upper-body obesity if in association with general obesity.(ABSTRACT TRUNCATED AT 250 WORDS)

Increasing prevalence of NIDDM in the Pacific island population of Western Samoa over a 13-year period

OBJECTIVE

A survey of noncommunicable diseases (NCD) in the Pacific island population of Western Samoa in 1978 (n = 1,206) documented a relatively high prevalence of non-insulin-dependent diabetes mellitus (NIDDM) and obesity. A follow-up survey was performed in 1991 (n = 1,776) to assess changes in NCD prevalence and risk factor distribution over 13 years.

RESEARCH DESIGN AND METHODS

In both surveys, the same representative villages from one urban and two rural areas were studied, and the survey procedure included an oral glucose tolerance test, anthropometric and blood pressure measurements, and physical activity assessment (1991 only).

RESULTS

The age-standardized prevalence of NIDDM in 1991 was 9.5 and 13.4% in Apia (urban) for men and women, respectively. In Poutasi (rural), 5.3% of men and 5.6% of women had NIDDM, and in Tuasivi (rural) the prevalence was 7.0 and 7.5% for men and women, respectively. Age, body mass index (BMI), waist-to-hip circumference ratio, physical inactivity, and family history of diabetes all showed independent association with NIDDM and impaired glucose tolerance. Living in Apia (compared with Poutasi) was also associated with NIDDM. Between 1978 and 1991, the age-standardized prevalence of NIDDM in Apia increased from 8.1 to 9.5% in men and 8.2 to 13.4% in women. In Poutasi, a dramatic increase occurred in prevalence from 0.1 to 5.3% in men, but little change in women was noted (5.4 to 5.6%). In Tuasivi, the increases were 2.3 to 7.0% in men and 4.4 to 7.5% in women. In combined survey areas, increases were observed in the age-standardized prevalence of obesity and mean levels of total cholesterol, fasting triglycerides, and uric acid between surveys as well as a reduction in the prevalence of smoking.

CONCLUSIONS

This is the first study using standardized methods to show a dramatic increase in the prevalence of NIDDM in a developing Pacific island population, and it indicates the importance of maintaining and expanding preventive programs for NIDDM and related lifestyle diseases in these populations.

Serum insulin and ECG abnormalities suggesting coronary heart disease in the populations of Mauritius and Nauru: cross-sectional and longitudinal associations

Cross-sectional associations between insulin and ECG abnormalities suggestive of 'possible' and 'probable' coronary heart disease (CHD) in the populations of Nauru (n = 568) and Mauritius (n = 3280) have been examined in both non-diabetic and diabetic subjects. Additionally, the longitudinal relationship between baseline insulin and incident ECG abnormalities has been explored in non-diabetic Nauruans (n = 177) over 5 years. Age-adjusted mean 2-hour serum insulin was generally higher in subjects with ECG abnormalities than those with a normal ECG, but the difference was significant only for non-diabetic Mauritian men (p < 0.01). There was no clear association between prevalence of ECG abnormalities and quintiles of fasting or 2-hr insulin in Mauritians, and in non-diabetic Nauruans there was a non-significant positive association between prevalence of ECG abnormalities and tertiles of 2-hr insulin. Logistic regression analyses showed a slight positive association between 2-hr insulin and ECG abnormalities in non-diabetic Mauritians (p = 0.06 in males, p = 0.09 in females), and non-diabetic male Nauruans (p = 0.054) independent of possible confounders. Fasting insulin was not associated in any group. In longitudinal analyses in Nauruans there were no significant differences in mean baseline fasting or 2-hr serum insulin between subjects who maintained a normal ECG and those who developed abnormalities consistent with 'possible CHD' (there were no changes suggestive of 'probable CHD'). The incidence of ECG changes suggesting 'possible CHD' was slightly higher in the upper tertile of baseline fasting insulin in both sexes and 2-hr insulin in females, but when other factors were accounted for, multiple logistic regression analyses did not support this finding. Data from the populations of Mauritius and Nauru do not support a major role for serum insulin in ECG abnormalities suggestive of CHD.

Incidence of IDDM in Mauritian children and adolescents from 1986 to 1990

OBJECTIVE

To document the incidence of IDDM in Mauritian children and adolescents 0-19 yr of age from 1986 to 1990.

RESEARCH DESIGN AND METHODS

We used a population-based register that used pediatricians, physicians, nutritionists, and general practitioners as a primary source of retrospective case ascertainment. The denominator data were obtained from the Statistics Office of the Ministry of Health (Port Louis, Mauritius).

RESULTS

In 1990, 37 newly diagnosed IDDM cases (22 females and 15 males) were identified between 1986 and 1990 among the population < or = 19 yr of age. The average incidence density per year was 1.9/100,000 people and was slightly higher among girls (2.2/100,000) than among boys (1.5/100,000). The average age-standardized incidence density was 2.1/100,000 people (95% confidence interval 1.5-3.0) among children < or = 14 yr of age, 2.5/100,000 people (95% confidence interval 1.5-3.9) among girls, and 1.8/100,000 people (95% confidence interval 1.0-3.0) among boys. The incidence was similarly low in Mauritians of Asian Indian, Chinese, and Creole (predominantly African) origin.

CONCLUSIONS

The incidence of IDDM in Mauritian children and adolescents is among the lowest yet reported. This sharply contrasts with the very high risk of NIDDM found among the adult population in this rapidly modernizing country.

Serum insulin distributions and reproducibility of the relationship between 2-hour insulin and plasma glucose levels in Asian Indian, Creole, and Chinese Mauritians. Mauritius NCD Study Group

The relationship of 2-hour (post-75 g oral glucose) serum insulin levels with plasma glucose levels was studied in a population-based random sample comprising 2,627 Hindu Indians, 685 Muslim Indians, 1,351 Creoles (African, European, and Indian admixture), and 415 Chinese from the Indian Ocean island of Mauritius. Known diabetic subjects taking oral hypoglycemic drugs or insulin were excluded from these analyses; 64% of all diabetic subjects had usable glucose and insulin data. Both fasting and 2-hour postload insulin levels were significantly higher in women than in men, and levels in both sexes were significantly greater in Hindu and Muslim Indian subjects than in Creoles or Chinese even after controlling for differences in age, body mass index (BMI), waist to hip ratio (WHR), and plasma glucose level. Levels in Muslims were higher than those in Hindus; it was unclear whether these ethnic differences represented hereditary or unmeasured environmental factors closely associated with ethnicity. All four ethnic groups demonstrated similar inverted U- or V-shaped curves when 2-hour insulin was plotted against either basal or 2-hour glucose. Both quadratic (U) and two-piece (V) regression models improved over linear models for 2-hour insulin versus either fasting or 2-hour glucose in all ethnic groups, although in statistical terms they were good models only for the 2-hour glucose comparison. The two-piece models were associated with modest increases in R2 compared with the quadratic models, but it was not possible to precisely determine optimal turning points with either model. However, in all ethnic groups, 2-hour insulin levels decreased above glucose levels of 7.1 to 7.8 (fasting) and 11.3 to 13.5 mmol/L (2-hour) in quadratic models, and 7.5 to 9.5 (fasting) and 8.5 to 10.5 mmol/L (2-hour) in two-piece models. The shape and point of inflection of the quadratic and two-piece curves were influenced little by gender, obesity, fat distribution, and physical activity. These results are in accord with those observed in cross-sectional and longitudinal studies in other ethnic groups, and support the generality of the plasma glucose levels currently used to define diabetes mellitus, which physiologically correspond with a decrease in beta-cell responsiveness to glucose. Asian Indians appear to have an ethnic propensity to hyperinsulinemia that is not explained by obesity or adverse fat distribution.

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)

Bimodality analysis of frequency distributions of 2-hour plasma glucose concentrations in the urban Micronesian population of Kiribati

Bimodality in the frequency distribution of plasma glucose 2 h after a 75-g oral glucose challenge has been demonstrated in only a few population groups, and the generalizability of the phenomenon remains unclear. Therefore, we have studied the distribution of 2-h glucose in 1813 Micronesians, aged 20 years and over, from an urbanized community of the Pacific Ocean Republic of Kiribati. The 2-h plasma glucose distributions were consistent with a mixture model comprising two lognormal components for age groups 30-39, 40-49 and 50+ years. The parameters of the mixture distribution were estimated by the method of maximum likelihood. The prevalence of non-insulin-dependent diabetes mellitus was 7.3% as defined by World Health Organization diagnostic criteria, and 4.7% when defined according to age-specific optimal cut-off values based on the minimization of the total number of misclassified individuals. Assuming that the fitted mixture distribution for each age group was the true plasma glucose distribution, the sensitivity and specificity of the World Health Organization diagnostic criteria and the age-specific optimal cut-off values were determined. Higher sensitivity with relatively little impairment of specificity resulted with the use of the former criteria. The prevalence of non-insulin-dependent diabetes mellitus increased with age as did the mean and standard deviation of the lower lognormal glucose component ("nondiabetics"). However, the mean and standard deviation of the "diabetic' upper component remained relatively constant and varied little with age.(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.