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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.

Objective: To measure ethnic differences in overall, cardiovascular, ischaemic heart disease and stroke mortality in the Republic of Mauritius., Design: Analysis of vital registration mortality data from 1989 to 1994 among Hindus, Muslims, Chinese and Creoles, aged 30-64 years, presented as age-standardized mortality rates, proportional mortality ratios and standardized mortality ratios., Results: During the six year period of analysis 10,657 deaths were recorded in men and 5008 in women. Mortality rates from ischaemic heart disease in Mauritian men are above the average of those found elsewhere. Ischaemic heart disease mortality in women and stroke mortality in both sexes are among the highest recorded in the world. Due to large ethnic differences in overall mortality, which could not be explained by the uncertainty about the exact population size by ethnic group, proportional mortality ratios are an inadequate measure of differential mortality between ethnic groups. 'Best' estimates of standardized mortality ratios indicate that in comparison to Hindus as the 'standard' population: (i) Creole women have lower ischaemic heart disease (by 34%) and stroke (by 22%) mortality; (ii) Creole women have lower ischaemic heart disease mortality (by 19%); (iii) Muslim men have lower stroke mortality (by 51%) and similar ischaemic heart disease mortality; (iv) Chinese men and women have markedly lower ischaemic heart disease (by 48% and 70%, respectively) and stroke mortality (by 54% and 48%, respectively)., Conclusion: The mortality rates of ischaemic heart disease and stroke of all ethnic groups in Mauritius, with the exception of the small Chinese ethnic minority, are very high by international standards. This pleads against differential allocation of resources for prevention strategies despite considerable differences in mortality rates from cardiovascular diseases between ethnic groups.

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.

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.

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.

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.

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)

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.

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.

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.

The prevalence of coronary heart disease (CHD) was determined in a population survey in Mauritius where the prevalence of non-insulin dependent diabetes and mortality from CHD are amongst the highest in the world. Men and women aged 35-74 years of all major ethnic groups were included: Asian Indians (Hindus and Muslims), Creoles and Chinese. ECG abnormalities suggesting either 'probable CHD' or 'possible CHD' were defined using standard criteria. The overall prevalence of probable CHD was 2.7% in men and 0.9% in women, and that of probable or possible CHD together 17.8% in men and 33.3% in women. The prevalence of CHD did not vary significantly between the four ethnic groups. In the multivariate analyses, age and high blood pressure were the most important independent predictors of ECG abnormalities. Neither diabetes nor serum insulin seemed to contribute independently to the prevalence of CHD. This survey confirmed the high ranking of Mauritius in international mortality statistics. The high rates of CHD seen in Asian Indians, African-origin Creoles and Chinese in the rapidly developing country of Mauritius may be a pointer to future problems in their regions of origin.

Associations with insulin resistance and islet beta-cell function have been studied cross-sectionally in a population-based sample of 4278 Mauritians comprising Asian Indian, Creole and Chinese subjects. Insulin resistance and beta-cell function were estimated by a computer solved model based on fasting plasma glucose and insulin concentrations. Insulin resistance increased with declining glucose tolerance, whereas beta-cell function was highest in subjects with impaired glucose tolerance (IGT) and lowest in those with non-insulin-dependent diabetes mellitus (NIDDM). Indian subjects had the highest beta-cell function, while ethnic differences in insulin sensitivity were less marked. This may indicate that deranged beta-cell function rather than insulin resistance is the primary determinant of hyperinsulinaemia and glucose intolerance in Asian Indians. beta-Cell function declined with age more sharply than did insulin sensitivity, suggesting that the age-related decline in glucose tolerance is primarily related to loss of beta-cell function. Body mass index, waist/hip ratio, physical inactivity and female sex were independently associated with insulin resistance and beta-cell function. Subjects with a family history of diabetes had increased insulin resistance, irrespective of glucose tolerance. This or similar models may have application in longitudinal population-based studies which seek to determine the relative contributions of insulin resistance and beta-cell function to the aetio-pathogenesis of NIDDM.