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.

An outbreak of Cyclospora infection on a cruise ship.

In 2010, an outbreak of cyclosporiasis affected passengers and crew on two successive voyages of a cruise ship that departed from and returned to Fremantle, Australia. There were 73 laboratory-confirmed and 241 suspected cases of Cyclospora infection reported in passengers and crew from the combined cruises. A case-control study performed in crew members found that illness was associated with eating items of fresh produce served onboard the ship, but the study was unable conclusively to identify the responsible food(s). It is likely that one or more of the fresh produce items taken onboard at a south-east Asian port during the first cruise was contaminated. If fresh produce supplied to cruise ships is sourced from countries or regions where Cyclospora is endemic, robust standards of food production and hygiene should be applied to the supply chain.

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.

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): 12.9­16.4). At least one secondary case occurred in 166 of the 595 households (a household transmission rate of 27.9%; 95% CI: 24.5­31.6).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.

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.

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.

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 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.

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.

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.

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.

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.

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.