ObjectiveIn adulthood, excess BMI is associated with cardiovascular disease (CVD); it is unknown whether risk differs by BMI trajectories from adolescence to adulthood.Design and MethodsThe National Longitudinal Study of Adolescent Health, a nationally representative, longitudinal adolescent cohort (mean age: 16.9y) followed into adulthood (mean age: 29.0y) [n=13,643 individuals (40,929 observations)] was examined. Separate logistic regression models for diabetes, hypertension, and inflammation were used to examine odds of risk factors at given adult BMI according to varying BMI trajectories from adolescence to adulthood.ResultsCVD risk factor prevalence at follow-up ranged from 5.5% (diabetes) to 26.4% (hypertension) and 31.3% (inflammation); risk differed across BMI trajectories. For example, relative to men aged 27y (BMI=23 kg/m2 maintained over full study period), odds for diabetes were comparatively higher for men of the same age and BMI≈30 kg/m2 with ≈8 BMI unit gain between 15-20y (OR=2.35; 95% CI, 1.51, 3.66) or in those who maintained BMI≈30 kg/m2 across the study period (OR=2.33; 1.92, 2.83) relative to the same ≈8 BMI unit gain, but between 20-27y (OR=1.44; 1.10, 1.87).ConclusionsSpecific periods and patterns of weight gain in the transition from adolescence to adulthood might be critical for CVD preventive efforts.

BackgroundHigh urbanicity and income are risk factors for cardiovascular-related chronic diseases in low- and middle-income countries, perhaps due to low physical activity (PA) in urban, high income areas. Few studies have examined differences in PA over time according to income and urbanicity in a country experiencing rapid urbanization.MethodsWe used data from the China Health and Nutrition Survey, a population-based cohort of Chinese adults (n = 20,083; ages 18-75y) seen a maximum of 7 times from 1991-2009. We used sex-stratified, zero-inflated negative binomial regression models to examine occupational, domestic, leisure, travel, and total PA in Chinese adults according to year, urbanicity, income, and the interactions among urbanicity, income, and year, controlling for age and region of China.ResultsWe showed larger mean temporal PA declines for individuals living in relatively low urbanicity areas (1991: 500 MET-hours/week; 2009: 300 MET-hours/week) compared to high urbanicity areas (1991: 200 MET-hours/week; 2009: 125 MET-hours/week). In low urbanicity areas, the association between income and total PA went from negative in 1991 (p < 0.05) to positive by 2000 (p < 0.05). In relatively high urbanicity areas, the income-PA relationship was positive at all time points and was statistically significant at most time points after 1997 (p < 0.05). Leisure PA was the only domain of PA that increased over time, but >95 % of individuals in low urbanicity areas reported zero leisure PA at each time point.ConclusionsOur findings show changing associations for income and urbanicity with PA over 18 years of urbanization. Total PA was lower for individuals living in more versus less urban areas at all time points. However, these differences narrowed over time, which may relate to increases in individual-level income in less urban areas of China with urbanization. Low-income individuals in higher urbanicity areas are a particularly critical group to target to increase PA in China.Electronic supplementary materialThe online version of this article (doi:10.1186/s12966-015-0321-2) contains supplementary material, which is available to authorized users.

Aims/hypothesisThe purpose of this study was to examine the association between urbanisation-related factors and diabetes prevalence in China.MethodsAnthropometry, fasting blood glucose (FBG) and community-level data were collected for 7,741 adults (18–90 years) across 217 communities and nine provinces in the 2009 China Health and Nutrition Survey to examine diabetes (FBG ≥7.0 mmol/l or doctor diagnosis). Sex-stratified multilevel models, clustered at the community and province levels and controlling for individual-level age and household income were used to examine the association between diabetes and: (1) a multicomponent urbanisation measure reflecting overall modernisation and (2) 12 separate components of urbanisation (e.g., population density, employment, markets, infrastructure and social factors).ResultsPrevalent diabetes was higher in more-urbanised (men 12%; women 9%) vs less-urbanised (men 6%; women 5%) areas. In sex-stratified multilevel models adjusting for residential community and province, age and household income, there was a twofold higher diabetes prevalence in urban vs rural areas (men OR 2.02, 95% CI 1.47, 2.78; women, OR 1.94, 95% CI 1.35, 2.79). All urbanisation components were positively associated with diabetes, with variation across components (e.g. men, economic and income diversity, OR 1.42, 95% CI 1.20, 1.66; women, transportation infrastructure, OR 1.18, 95% CI 1.06, 1.32). Community-level variation in diabetes was comparatively greater for women (intraclass correlation [ICC] 0.03–0.05) vs men (ICC ≤0.01); province-level variation was greater for men (men 0.03–0.04; women 0.02).Conclusions/interpretationDiabetes prevention and treatment efforts are needed particularly in urbanised areas of China. Community economic factors, modern markets, communications and transportation infrastructure might present opportunities for such efforts.Electronic supplementary materialThe online version of this article (doi:10.1007/s00125-012-2697-8) contains peer-reviewed but unedited supplementary material, which is available to authorised users.

Background/Objectives:Nonglycemic factors like iron deficiency (ID) or anemia may interfere with classification of diabetes and prediabetes using hemoglobin A1c (HbA1c). However, few population-based studies of diabetes in areas with endemic ID/anemia have been conducted. We aimed to determine how mutually exclusive categories of ID alone, anemia alone and iron-deficiency anemia (IDA) were each associated with prediabetes and diabetes prevalence using fasting blood glucose (FBG) versus HbA1c in a population-based study of adults with endemic ID/anemia.Subjects/Methods:We used data from the China Health and Nutrition Survey, a longitudinal, population-based study across 228 communities within nine provinces of China. This analysis included 7308 adults seen in the 2009 survey aged 18–75 years. We used descriptive and covariate-adjusted models to examine relative risk of prediabetes and diabetes using FBG alone, HbA1c alone, HbA1c and FBG, or neither (normoglycemia) by anemia alone, ID alone, IDA or normal iron/hemoglobin.Results:Approximately 65% of individuals with diabetes in our sample were concordantly classified with diabetes using both FBG and HbA1c, while 35% had a discordant diabetes classification: they were classified using either FBG or HbA1c, but not both. Fewer participants with ID alone versus normal iron/hemoglobin were classified with diabetes using HbA1c only. From covariate-adjusted, multinomial regression analyses, the adjusted prevalence of prediabetes using HbA1c only was 22% for men with anemia alone, but 13% for men with normal iron/hemoglobin. In contrast, the predicted prevalence of prediabetes using HbA1c only was 8% for women with ID alone, compared with 13% for women with normal iron/hemoglobin.Conclusions:These findings suggest potential misclassification of diabetes using HbA1c in areas of endemic ID/anemia. Estimating diabetes prevalence using HbA1c may result in under-diagnosis in women with ID and over-diagnosis in men with anemia.

Objective Little is known about whether large-scale environmental changes, such as those seen with urbanization, are differentially associated with systolic versus diastolic blood pressure, and whether those changes vary by birth cohort. Methods We used data from the China Health and Nutrition Survey, a population-based cohort study of Chinese adults (n=18,976; ages 18–70y) seen a maximum of 7 times over 1991–2009. We used hierarchical multivariable linear models to simultaneously estimate systolic and diastolic blood pressure as correlated outcomes over time, accounting for their physiologic, time-varying correlation. Main exposure variables were urbanicity, age, and birth cohort. Over 18 years of modernization, median systolic and diastolic blood pressure increased by 10 and 7 mm Hg, respectively. Results Our hierarchical model results suggest greater temporal increases in systolic and particularly diastolic blood pressure at lower versus higher urbanicity. At the same chronological age, for a 10-year difference in birth cohort (i.e., born in 1980s versus 1970s) the adjusted mean diastolic blood pressure was ~3mm Hg higher for the later birth cohort (p<0.001). Pulse pressure (calculated as model-predicted systolic minus diastolic blood pressure) was also higher at low versus high urbanicity. Conclusions These results suggest increased susceptibility of diastolic blood pressure (and thus peripheral vascular resistance) to environmental change, particularly in younger Chinese adults. Because diastolic blood pressure more strongly predicts cardiovascular disease risk in younger adulthood, hypertension-related health burden in China may increase over time.