Left ventricular hypertrophy: an ECG-based study of prevalence and risk factors in a multiethnic population.

BACKGROUND: Left ventricular hypertrophy (LVH) is frequently seen in association with arterial hypertension and indicates poor prognosis. This study aimed to determine the prevalence of LVH and associated factors in a multiethnic population from Mauritius. METHODS: Population-based health surveys were performed in 2009 and 2015 and included in total 8961 individuals aged 35-75 years with recorded 12-lead ECG. LVH was defined according to three criteria: Sokolow-Lyon, Cornell voltage and Cornell product. Data were collected about health and lifestyle behaviour. Anthropometry and blood pressure were measured. Fasting levels of blood lipids and glucose were determined, oral glucose tolerance test was performed in people without glucose-lowering medications. RESULTS: The age-standardised prevalence of LVH was 9% (n=875) according to any of the three ECG criteria. Individuals with LVH were older, more likely to have hypertension, diabetes, known cardiovascular disease (CVD) and elevated levels of cholesterol and creatinine. Further, they were more likely to be of African descent (Creole) and have lower educational level. In a multivariable model, Creole (OR (95% CI)) (1.56 (1.33 to 1.83)), low educational level (1.49 (1.28 to 1.75)), hypertension (3.01 (2.55 to 3.56)), known CVD (1.42 (1.11 to 1.83)) and elevated creatinine (1.08 (1.03 to 1.14)) remained associated with LVH. Individuals with non-treated or uncontrolled hypertension had a higher risk for LVH (3.09 (95% CI 2.57 to 3.71) and 4.07 (95% CI 3.29 to 5.05), respectively), than individuals with well controlled hypertension or normotension. CONCLUSION: LVH occurs more frequently in individuals with hypertension, as well as in individuals with African ancestry and/or low education level.

Association between type 2 diabetes mellitus and disability: What is the contribution of diabetes risk factors and diabetes complications?

BACKGROUND: The aim of this study was to evaluate the association between type 2 diabetes and disability in Mauritius and to assess the extent to which the effect of diabetes is explained by diabetes risk factors and concomitant complications. METHODS: Data from a national survey in the multiethnic nation of Mauritius, which comprises South Asians and African Creoles, were analyzed. Disability was measured using the Katz activities of daily living questionnaire in participants aged >50 years. RESULTS: Among 3692 participants, 487 (13.2%) had some level of disability. Diabetes was associated with significantly higher risk of disability (odds ratio [OR] 1.67; 95% confidence interval [CI] 1.34-2.08). After adjusting for demographic, behavioral, and metabolic factors, as well as comorbidities, disability was significantly associated with diabetes among African Creoles (OR 2.03; 95% CI 1.16-3.56), but not South Asians (OR 1.27; 95% CI 0.98-1.66). Obesity explained much of the association between diabetes and disability (excess percentage of risk: 26.3% in South Asians and 12.1% in African Creoles). Obesity, history of cardiovascular disease (CVD), asthma-like symptoms, and depression together explained 46.5% and 29.0% of the excess risk in South Asians and African Creoles, respectively. CONCLUSIONS: Diabetes is associated with a 67% increased risk of disability. Diabetes risk factors and comorbidities explain more of the association between diabetes and disability among South Asians than Africans. Obesity and history of CVD explained the largest percentage of the relationship between diabetes and disability, indicating that weight and CVD management may be helpful in controlling disability related to diabetes.

Diabetes mellitus prevalence is increasing in South Asians but is stable in Chinese living in Singapore and Mauritius.

BACKGROUND: Asia is experiencing a type 2 diabetes epidemic, but prevalence differs by ethnicity and level of socioeconomic development. Singapore and Mauritius have implemented comprehensive campaigns to address this public health problem. We compared diabetes and obesity prevalence trends among Chinese and South Asians living in Singapore and Mauritius to determine the contribution of ethnicity and economic development to diabetes. METHODS: Age-specific data from serial national population-based surveys in Singapore and Mauritius between 1987 and 2010 were used to estimate age-standardized diabetes and obesity prevalence. Modified Breslow-Cox proportional hazard models were used to obtain rate ratios for diabetes risk factors. RESULTS: In Singapore, the age-standardized prevalence of diabetes remained stable for Chinese (men: 14% in 1992, 13% in 2010; women: 12% in 1992, 10% in 2010), but increases were observed for South Asians (men: 20% in 1992, 26% in 2010; women: 18% in 1992, 20% in 2010). There were similar patterns in Mauritius. In both countries, obesity prevalence trends were stable for Chinese women, but increased for Chinese men and South Asians. Associations between obesity and diabetes were stronger in Chinese than South Asians regardless of country. CONCLUSIONS: Despite different socioeconomic settings in Singapore and Mauritius, we observed rising diabetes prevalence among South Asians but stable prevalence in Chinese in both countries. This provides further evidence that ethnicity contributes to the development of diabetes, and that there should be an increased emphasis on future prevention strategies targeting South Asian populations in these countries.

Epigenome-wide association of DNA methylation markers in peripheral blood from Indian Asians and Europeans with incident type 2 diabetes: a nested case-control study.

BACKGROUND: Indian Asians, who make up a quarter of the world's population, are at high risk of developing type 2 diabetes. We investigated whether DNA methylation is associated with future type 2 diabetes incidence in Indian Asians and whether differences in methylation patterns between Indian Asians and Europeans are associated with, and could be used to predict, differences in the magnitude of risk of developing type 2 diabetes. METHODS: We did a nested case-control study of DNA methylation in Indian Asians and Europeans with incident type 2 diabetes who were identified from the 8-year follow-up of 25 372 participants in the London Life Sciences Prospective Population (LOLIPOP) study. Patients were recruited between May 1, 2002, and Sept 12, 2008. We did epigenome-wide association analysis using samples from Indian Asians with incident type 2 diabetes and age-matched and sex-matched Indian Asian controls, followed by replication testing of top-ranking signals in Europeans. For both discovery and replication, DNA methylation was measured in the baseline blood sample, which was collected before the onset of type 2 diabetes. Epigenome-wide significance was set at p<1 × 10(-7). We compared methylation levels between Indian Asian and European controls without type 2 diabetes at baseline to estimate the potential contribution of DNA methylation to increased risk of future type 2 diabetes incidence among Indian Asians. FINDINGS: 1608 (11·9%) of 13 535 Indian Asians and 306 (4·3%) of 7066 Europeans developed type 2 diabetes over a mean of 8·5 years (SD 1·8) of follow-up. The age-adjusted and sex-adjusted incidence of type 2 diabetes was 3·1 times (95% CI 2·8-3·6; p<0·0001) higher among Indian Asians than among Europeans, and remained 2·5 times (2·1-2·9; p<0·0001) higher after adjustment for adiposity, physical activity, family history of type 2 diabetes, and baseline glycaemic measures. The mean absolute difference in methylation level between type 2 diabetes cases and controls ranged from 0·5% (SD 0·1) to 1·1% (0·2). Methylation markers at five loci were associated with future type 2 diabetes incidence; the relative risk per 1% increase in methylation was 1·09 (95% CI 1·07-1·11; p=1·3 × 10(-17)) for ABCG1, 0·94 (0·92-0·95; p=4·2 × 10(-11)) for PHOSPHO1, 0·94 (0·92-0·96; p=1·4 × 10(-9)) for SOCS3, 1·07 (1·04-1·09; p=2·1 × 10(-10)) for SREBF1, and 0·92 (0·90-0·94; p=1·2 × 10(-17)) for TXNIP. A methylation score combining results for the five loci was associated with future type 2 diabetes incidence (relative risk quartile 4 vs quartile 1 3·51, 95% CI 2·79-4·42; p=1·3 × 10(-26)), and was independent of established risk factors. Methylation score was higher among Indian Asians than Europeans (p=1 × 10(-34)). INTERPRETATION: DNA methylation might provide new insights into the pathways underlying type 2 diabetes and offer new opportunities for risk stratification and prevention of type 2 diabetes among Indian Asians. FUNDING: The European Union, the UK National Institute for Health Research, the Wellcome Trust, the UK Medical Research Council, Action on Hearing Loss, the UK Biotechnology and Biological Sciences Research Council, the Oak Foundation, the Economic and Social Research Council, Helmholtz Zentrum Munchen, the German Research Center for Environmental Health, the German Federal Ministry of Education and Research, the German Center for Diabetes Research, the Munich Center for Health Sciences, the Ministry of Science and Research of the State of North Rhine-Westphalia, and the German Federal Ministry of Health.

The performance of diabetes risk prediction models in new populations: the role of ethnicity of the development cohort.

It is believed that diabetes risk scores need to be ethnic specific. However, this prerequisite has not been tested. We examined the performance of several risk models, developed in various populations, in a Europid and a South Asian population. The performance of 14 published risk prediction models were tested in two prospective studies: the Australian Diabetes, Obesity and Lifestyle (AusDiab) study and the Mauritius non-communicable diseases survey. Eight models were developed in Europid populations; the remainder in various non-Europid populations. Model performance was assessed using area under the receiver operating characteristic curves (discrimination), Hosmer-Lemeshow tests (goodness-of-fit) and Brier scores (accuracy). In both AusDiab and Mauritius, discrimination was highest for a model developed in a mixed population (non-Hispanic white and African American) and lowest for a model developed in a Europid population. Discrimination for all scores was higher in AusDiab than in Mauritius. For almost all models, goodness-of-fit was poor irrespective of the ethnicity of the development cohort, and accuracy was higher in AusDiab compared to Mauritius. Our results suggest that similarity of ethnicity or similarity of diabetes risk may not be the best way of identifying models that will perform well in another population. Differences in study methodology likely account for much of the difference in the performance. Thus, identifying models which use measurements that are clearly described and easily reproducible for both research and clinical settings may be more important.

Plasma levels of soluble interleukin 1 receptor accessory protein are reduced in obesity.

CONTEXT: Adipokines actuate chronic, low-grade inflammation through a complex network of immune markers, but the current understanding of these networks is incomplete. The soluble isoform of the IL-1 receptor accessory protein (sIL1RAP) occupies an important position in the inflammatory pathways involved in obesity. The pathogenetic and clinical influences of sIL1RAP are unknown. OBJECTIVE: The objective of the study was to elucidate whether plasma levels of sIL1RAP are reduced in obesity, using affluent clinical, biochemical, and genetic data from two diverse cohorts. DESIGN, SETTING, AND PARTICIPANTS: The study was conducted in two cohorts: the San Antonio Family Heart Study (n = 1397 individuals from 42 families) and South Asians living in Mauritius, n = 230). MAIN OUTCOME MEASURES: Plasma sIL1RAP levels were measured using an ELISA. The genetic basis of sIL1RAP levels were investigated using both a large-scale gene expression profiling study and a genome-wide association study. RESULTS: A significant decrease in plasma sIL1RAP levels were observed in obese subjects, even after adjustment for age and sex. The sIL1RAP levels demonstrated a strong inverse association with obesity measures in both populations. All associations were more significant in females. Plasma sIL1RAP levels were significantly heritable, correlated with IL1RAP transcript levels (NM_134470), showed evidence for shared genetic influences with obesity measures and were significantly associated with the rs2885373 single-nucleotide polymorphism (P = 6.7 × 10(-23)) within the IL1RAP gene. CONCLUSIONS: Plasma sIL1RAP levels are reduced in obesity and can potentially act as biomarkers of obesity. Mechanistic studies are required to understand the exact contribution of sIL1RAP to the pathogenesis of obesity.

Effectiveness of green tea in a randomized human cohort: relevance to diabetes and its complications.

Epidemiological studies have argued that green tea could mitigate diabetes and its complications. This study investigated the phytophenolic profile of Mauritian green tea and its antioxidant propensity. The effect of green tea on the risk factors: waist-hip ratio, glucose level, arterial pressure, antioxidant status, and alanine aminotransferase (ALT) in prediabetics was assessed. The experimental group consumed 3 cups of green tea daily for 14 weeks followed by a 2-week washout period. The control group followed a water regimen. Green tea contained high level of phenolics related to its antioxidant power. Green tea suppressed waist-hip ratio of women from a significant increase and suppressed mean arterial pressure of men and women from a significant decrease after week 14. It reduced ALT level in women by 13.0% (P < 0.1) while increasing the antioxidant potential of men and women sera by 2.7% (P < 0.1) and 5.1% (P < 0.1). The study timescale may have been too short to enable demonstration of effects on fasting plasma glucose and HbA1c outcomes. Green tea regimen could form part of a healthy lifestyle that might ameliorate features of metabolic syndrome and subsequent risks for diabetes and its complications. This trial is registered with ClinicalTrials.gov NCT01248143.

Glucose-independent ethnic differences in HbA1c in people without known diabetes.

OBJECTIVE: To determine whether glucose-independent differences in HbA1c exist between people of African, South Asian, and Chinese ethnicities. RESEARCH DESIGN AND METHODS: Data from 6,701 people aged 19-78 years, without known diabetes, from Mauritius, and participating in the population-based Non-Communicable Disease Surveys of the main island and the island of Rodrigues were included. Participants were African (n = 1,219 from main island, n = 1,505 from Rodrigues), South Asian (n = 3,820), and Chinese (n = 157). Survey data included HbA1c, plasma glucose during oral glucose tolerance testing (OGTT), anthropometry, demographics, and medical and lifestyle history. RESULTS: Mean HbA1c, after adjustment for fasting and 2-h plasma glucose and other factors known to influence HbA1c, was higher in Africans from Rodrigues (6.1%) than in South Asians (5.7%, P < 0.001), Chinese (5.7%, P < 0.001), or Africans from the main island of Mauritius (5.7%, P < 0.001). The age-standardized prevalence of diabetes among Africans from Rodrigues differed substantially depending on the diagnostic criteria used [OGTT 7.9% (95% CI 5.8-10.0); HbA1c 17.3% (15.3-19.2)]. Changing diagnostic criteria resulted in no significant change in the prevalence of diabetes within the other ethnic groups. CONCLUSIONS: People of African ethnicity from Rodrigues have higher HbA1c than those of South Asian or African ethnicity from the main island of Mauritius for reasons not explained by plasma glucose during an OGTT or traditional factors known to affect glycemia. Further research should be directed at determining the mechanism behind this disparity and its relevance to clinical outcomes.

All-cause cancer mortality over 15 years in multi-ethnic Mauritius: the impact of diabetes and intermediate forms of glucose tolerance.

There are accumulating data describing the association between diabetes and cancer mortality from Westernised populations. There are no data describing the relationship between diabetes and cancer mortality in African or South Asian populations from developing countries. We explored the relationship of abnormal glucose tolerance and diabetes on cancer mortality risk in a large, multi-ethnic cohort from the developing nation of Mauritius. Population-based surveys were undertaken in 1987, 1992 and 1998. The 9559 participants comprised 66% of South Asian (Indian), 27% of African (Creole), and 7% of Chinese descent. Cox's proportional hazards model with time varying covariates was used to obtain hazard ratios (HRs) and 95% confidence intervals (95% CI) for risk of cancer mortality, after adjustment for confounding factors. In men, but not women, cancer mortality risk increased with rising 2h-PG levels with HR for the top versus bottom quintile of 2.77 (95%CI: 1.28 to 5.98). South Asian men with known diabetes had a significantly greater risk of cancer mortality than those with normal glucose tolerance (NGT) HR: 2.74 (95%CI: 1.00-7.56). Overall, impaired glucose tolerance was associated with an elevated risk of cancer mortality compared to NGT (HR: 1.47, 95% CI: 0.98-2.19), though this was not significant. We have shown that the association between abnormal glucose tolerance and cancer extends to those of African and South Asian descent. These results highlight the importance of understanding this relationship in a global context to direct future health policy given the rapid increase in type 2 diabetes, especially in developing nations.

Explaining the increase of diabetes prevalence and plasma glucose in Mauritius.

OBJECTIVE: Secular trends in the epidemiology of diabetes are best described by studying the same population over time, but few such studies exist. Using surveys from Mauritius in 1987 and 2009, we examined 1) the change in the prevalence of diabetes, 2) the extent to which changes in traditional diabetes risk factors explained the increase, and 3) the change in the distribution of plasma glucose levels over time. RESEARCH DESIGN AND METHODS: Independent population-based surveys were undertaken in Mauritius in 1987 and 2009 using similar methodology in adults aged 20-74 years. Physical measurements and fasting blood samples were taken, and an oral glucose tolerance test was performed at both surveys. RESULTS: The age-standardized prevalence of diabetes in 2009 was 22.3% (95% CI 20.0-24.6) among men and 20.2% (18.3-22.3) among women, representing an increase since 1987 of 64 and 62% among men and women, respectively. Concurrent changes in the distribution of age, ethnicity, waist circumference, BMI, physical activity, smoking, family history of diabetes, and hypertension explained more of the increase in the prevalence of diabetes in men than in women. Increases in plasma glucose (especially fasting glucose) were seen across the population but were greater at the upper levels. CONCLUSIONS: In Mauritius, there has been a marked increase in diabetes prevalence over 22 years. This mainly results from changes in traditional risk factors, leading to population-wide increases in plasma glucose levels. Interventions to control this escalation of diabetes should focus on population-wide strategies.

Genome-wide association study in individuals of South Asian ancestry identifies six new type 2 diabetes susceptibility loci.

We carried out a genome-wide association study of type-2 diabetes (T2D) in individuals of South Asian ancestry. Our discovery set included 5,561 individuals with T2D (cases) and 14,458 controls drawn from studies in London, Pakistan and Singapore. We identified 20 independent SNPs associated with T2D at P < 10(-4) for testing in a replication sample of 13,170 cases and 25,398 controls, also all of South Asian ancestry. In the combined analysis, we identified common genetic variants at six loci (GRB14, ST6GAL1, VPS26A, HMG20A, AP3S2 and HNF4A) newly associated with T2D (P = 4.1 × 10(-8) to P = 1.9 × 10(-11)). SNPs at GRB14 were also associated with insulin sensitivity (P = 5.0 × 10(-4)), and SNPs at ST6GAL1 and HNF4A were also associated with pancreatic beta-cell function (P = 0.02 and P = 0.001, respectively). Our findings provide additional insight into mechanisms underlying T2D and show the potential for new discovery from genetic association studies in South Asians, a population with increased susceptibility to T2D.

Genome-wide scan identifies a quantitative trait locus at 4p15.3 for serum urate.

Elevated serum urate levels lead to gout and are associated with hypertension, metabolic syndrome, type 2 diabetes and cardiovascular diseases. The purpose of this study was to identify evidence for genetic linkage with serum urate and to determine whether variation within positional candidate genes is associated with serum urate levels in a non-European population. Genetic linkage analysis and single nucleotide polymorphism (SNP) genotyping was performed in a large family pedigree cohort from Mauritius. We assessed associations between serum urate levels and 97 SNPs in a positional candidate gene, SLC2A9. A genome-wide scan identified a new region with evidence for linkage for serum urate at 4p15.3. SNP genotyping identified significant association between six SNP variants in SLC2A9 and serum urate levels. Allelic and gender-based effects were noted for several SNPs. Significant correlations were also observed between serum urate levels and individual components of metabolic syndrome. Our study results implicate genetic variation in SLC2A9 in influencing levels of serum urate over a broad range of values in a large Mauritian family cohort.

Mortality, all-cause and cardiovascular disease, over 15 years in multiethnic mauritius: impact of diabetes and intermediate forms of glucose tolerance.

OBJECTIVE: Little information is available on the impact of abnormal glucose tolerance on mortality in South Asian and African populations in the developing world. We explored this issue in a large, multiethnic cohort from the developing nation of Mauritius. RESEARCH DESIGN AND METHODS: Population-based surveys were undertaken in 1987, 1992, and 1998. The 9,559 participants (20-82 years old) comprised 66% South Asian (Indian), 27% Creole (African), and 7% Chinese descent. Mortality was ascertained in 2007. RESULTS: Over a median 15.1-year follow-up, 1,557 participants died. Compared with those with normal glucose tolerance, the all-cause mortality hazard ratios (HR) for known diabetes, newly diagnosed diabetes, and impaired glucose tolerance were 3.35 (95% CI 2.77-4.04), 2.11 (1.73-2.57), and 1.53 (1.26-1.87) in South Asians and 2.14 (1.65-2.79), 1.41 (1.06-1.88), and 1.08 (0.83-1.40) in Africans, respectively. Those with impaired fasting glucose were not at increased risk in either ethnicity. In the Chinese, only those with known diabetes were at increased risk of mortality with HR 3.68 (1.87-7.25). CONCLUSIONS: This is the first study in a developing country of the impact of glucose intolerance on mortality in an African population, and one of the first studies of a South Asian population. It shows that the impact on mortality in these populations in Mauritius is comparable to that seen in developed countries. These results are important in a global context for future health policy in light of the impact of the rapid increase in prevalence of diabetes, especially in developing nations.

Genetic influences on type 2 diabetes and metabolic syndrome related quantitative traits in Mauritius.

Epidemiological studies report a high prevalence of type 2 diabetes and metabolic syndrome in the island nation of Mauritius. The Mauritius Family Study was initiated to examine heritable factors that contribute to these high rates of prevalence and consists of 400 individuals in 24 large extended multigenerational pedigrees. Anthropometric and biochemical measurements relating to the metabolic syndrome were undertaken in addition to family and lifestyle based information for each individual. Variance components methods were used to determine the heritability of the type 2 diabetes and metabolic syndrome related quantitative traits. The cohort was made up of 218 females (55%) and 182 males with 22% diagnosed with type 2 diabetes and a further 30% having impaired glucose tolerance or impaired fasting glucose. Notably BMI was not significantly increased in those with type 2 diabetes (P= .12), however a significant increase in waist circumference was observed in these groups (P= .02). The heritable proportion of trait variance was substantial and greater than values previously published for hip circumference, LDL and total cholesterol, diastolic and systolic blood pressure and serum creatinine. Height, weight and BMI heritabilities were all in the upper range of those previously reported. The phenotypic characteristics of the Mauritius family cohort are similar to those previously reported in the Mauritian population with a high observed prevalence rate of type 2 diabetes. A high heritability for key type 2 diabetes and metabolic syndrome related phenotypes (range 0.23 to 0.68), suggest the cohort will have utility in identifying genes that influence these quantitative traits.