Urban environment as an independent predictor of insulin resistance in a South Asian population.

BACKGROUND: Developing countries, such as India, are experiencing rapid urbanization, which may have a major impact on the environment: including worsening air and water quality, noise and the problems of waste disposal. We used health data from an ongoing cohort study based in southern India to examine the relationship between the urban environment and homeostasis model assessment of insulin resistance (HOMA-IR). METHODS: We utilized three metrics of urbanization: distance from urban center; population density in the India Census; and satellite-based land cover. Restricted to participants without diabetes (N = 6350); we built logistic regression models adjusted for traditional risk factors to test the association between urban environment and HOMA-IR. RESULTS: In adjusted models, residing within 0-20 km of the urban center was associated with an odds ratio for HOMA-IR of 1.79 (95% CI 1.39, 2.29) for females and 2.30 (95% CI 1.64, 3.22) for males compared to residing in the furthest 61-80 km distance group. Similar statistically significant results were identified using the other metrics. CONCLUSIONS: We identified associations between urban environment and HOMA-IR in a cohort of adults. These associations were robust using various metrics of urbanization and adjustment for individual predictors. Our results are of public health concern due to the global movement of large numbers of people from rural to urban areas and the already large burden of diabetes.

Sodium Intake, Blood Pressure, and Dietary Sources of Sodium in an Adult South Indian Population.

BACKGROUND: The association between prevalence of hypertension and its relationship with dietary sodium intake has never been published from large epidemiological studies in the South Indian population before. OBJECTIVES: To assess sodium intake and its association with blood pressure, and major dietary sources of sodium in an adult population in southeastern India. METHODS: This study included a representative population-based sample of 8080 individuals (57% women) >20 years of age. Individuals with previous history of hypertension and outliers for sodium intake were excluded, resulting in a sample size of 6876, with 4269 from semi-urban/urban and 2607 from rural areas. Baseline measurements included evaluation of systolic (SBP) and diastolic (DBP) blood pressures, anthropometric, sociodemographic, and psychosocial parameters. Based on 24-hour recall, we calculated total daily sodium intake and the percentage contributed by each food group to the total sodium intake. Participants were assigned based on quintiles of dietary sodium intake. Mixed-effects multivariable linear regression models assessed the association of SBP and DBP with sodium intake. FINDINGS: Men had higher mean sodium intake (4.1 ± 2 versus 3.2 ± 1.7 g/day; P < 0.01) with higher mean SBP and DBP (123/77 versus 117/74 mm Hg; P < 0.01), and higher prevalence of hypertension (22.2% versus 12.9%; P < 0.01) compared with women. Mean dietary sodium intake was significantly higher in the hypertensive men (4.2 ± 2 g/day) and women (3.2 ± 1.7 g/day) compared with normotensive men (4 ± 2 g/day), and women (3.2 ± 1.7 g/day; P < 0.05). Significant (P < 0.01) increases in SBP and DBP were evident in men, but not women with increasing quintile of sodium intake. After multivariable adjustments, sodium intake was independently associated with SBP, but not DBP, in both sexes. The predominant source of dietary sodium in both semi-urban/urban and rural populations was from homemade foods where salt is part of the traditional recipe. CONCLUSION: In a South Indian population, the dietary intake of sodium was higher than recommendations by major dietary guidelines and was an independent predictor of SBP.

Population Study of Urban, Rural, and Semiurban Regions for the Detection of Endovascular Disease and Prevalence of Risk Factors and Holistic Intervention Study: Rationale, Study Design, and Baseline Characteristics of PURSE-HIS.

We designed and implemented the PURSE-HIS (Population Study of Urban, Rural and Semiurban Regions for the Detection of Endovascular Disease and Prevalence of Risk Factors and Holistic Intervention Study) to understand the prevalence and progression of subclinical and overt endovascular disease (EVD) and its risk factors in urban, semiurban, and rural communities in South India. The study is also designed to generate clinical evidence for effective, affordable, and sustainable community-specific intervention strategies to control risks factors for EVD. As of June 2012, 8,080 (urban: 2,221; semiurban: 2,821; rural: 3,038) participants >20 years of age were recruited using 2-stage cluster sampling. Baseline measurements included standard cardiovascular disease risk factors, sociodemographic factors, lifestyle habits, psychosocial factors, and nutritional assessment. Fasting blood samples were assayed for putative biochemical risk factors and urine samples for microalbuminuria. All nondiabetic participants underwent oral glucose tolerance test with blood and urine samples collected every 30 min for 2 h. Additional baseline measurements included flow-mediated brachial artery endothelial vasodilation, assessment of carotid intimal medial wall thickness using ultrasonography, screening for peripheral vascular disease using ankle and brachial blood pressures, hemodynamic screening using a high-fidelity applanation tonometry to measure central blood pressure parameters, and aortic pulse wave velocity. To assess prevalence of coronary artery disease, all participants underwent surface electrocardiography and documentation of ventricular wall motion abnormality and function using echocardiography imaging. To detect subclinical lesions, all eligible participants completed an exercise treadmill test. Prospectively, the study will assess progression of subclinical and overt EVD, including risk factor-outcome relation differences across communities. The study will also evaluate community-specific EVD prevention using traditional Indian system of medicine versus recognized allopathic (mainstream) systems of medicine.