Combined effects of air pollution in adulthood and famine exposure in early life on type 2 diabetes

Huo, Wenqian; Hou, Jian; Nie, Luting; Mao, Zhenxing; Liu, Xiaotian; Chen, Gongbo; Xiang, Hao; Li, Shanshan; Lee, Hyewon; Wang, Chongjian

doi:10.1007/s11356-021-18193-9

Cited by 3 publications

(5 citation statements)

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“…From these 14 studies, five studies were selected as the representative studies [ 28 , 30 , 33 , 34 , 38 ], and the other nine were excluded. Therefore, 23 Chinese famine studies on T2D were included for this review [ 28 , 30 , 33 , 34 , 38 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 ].…”

Section: Resultsmentioning

confidence: 99%

“…Figure 3 A shows the age differences of famine births and the three control groups. The age difference was three years or more when comparing famine births to either postfamine or prefamine births and one year or less comparing famine births to combined pre- and postfamine births, except in three studies (studies 18, 21 and 23) [ 55 , 57 , 59 ]. This shows that the age difference between famine births and controls will be smallest when combining prefamine and postfamine births as controls.…”

Section: Resultsmentioning

confidence: 99%

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Early-Life Exposure to the Chinese Famine of 1959–1961 and Type 2 Diabetes in Adulthood: A Systematic Review and Meta-Analysis

Lumey

2022

Nutrients

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Background: The fast-growing literature suggests that the Chinese famine of 1959–1961 drives current and future type 2 diabetes (T2D) epidemics in China. This conclusion may be premature, as many Chinese famine studies have major methodological problems. We examine these problems, demonstrate how they bias the study results, and formulate recommendations to improve the quality of future studies. Methods: We searched English and Chinese databases for studies that examined the relationship between prenatal exposure to the Chinese famine and adult T2D from inception to 8 February 2022. We extracted information on T2D cases and study populations of individuals born during the famine (famine births), before the famine (prefamine births), and after the famine (postfamine births). We used random-effects models to compare the odds of T2D in famine births to several control groups, including postfamine births, combined pre- and postfamine births, and prefamine births. We used meta-regressions to examine the impacts of age differences between comparison groups on famine effect estimates and the role of other characteristics, including participant sex, age, and T2D assessments; famine intensity; residence; and publication language. Potential sources of heterogeneity and study quality were also evaluated. Results: Twenty-three studies met our inclusion criteria. The sample sizes ranged from less than 300 to more than 360,000 participants. All studies defined the famine exposure based on the participants’ dates of birth, and 18 studies compared famine births and postfamine births to estimate famine effects on T2D. The famine and postfamine births had an age difference of three years or more in all studies. The estimates of the famine effect varied by the selection of controls. Using postfamine births as controls, the OR for T2D among famine births was 1.50 (95% CI 1.34–1.68); using combined pre- and postfamine births as controls, the OR was 1.12 (95% CI 1.02–1.24); using prefamine births as controls, the OR was 0.89 (95% CI 0.79–1.00). The meta-regressions further showed that the famine effect estimates increased by over 1.05 times with each one-year increase in ignored age differences between famine births and controls. Other newly identified methodological problems included the poorly assessed famine intensity, unsuitable study settings for famine research, and poor confounding adjustment. Interpretation: The current estimates of a positive relationship between prenatal exposure to the Chinese famine and adult T2D are mainly driven by uncontrolled age differences between famine births and postfamine births. Studies with more rigorous methods, including age-balanced controls and robust famine intensity measures, are needed to quantify to what extent the famine exposure is related to current T2D patterns in China.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Early-Life Exposure to the Chinese Famine of 1959–1961 and Type 2 Diabetes in Adulthood: A Systematic Review and Meta-Analysis

Lumey

2022

Nutrients

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“…[3][4][5]15,46,47] Most published articles in China have shown that famine exposure early in life increases the risk of developing type 2 diabetes. [4,7,13,15,16,[48][49][50][51][52][53][54] However, one study on China's famine indicated that individuals who suffered famine early in life did not have a rise in type 2 diabetes compared to non-exposed people. [55] These discrepancies may be due to the different sample selection effects and methodological differences in defining groups exposed to famine.…”

Section: Discussionmentioning

confidence: 99%

Individual and combined effects of famine exposure and obesity parameters on type 2 diabetes in middle-aged and older adults: A population-based cross-sectional study

Li,

Sun

et al. 2024

Medicine

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Malnutrition early in life may have adverse effects on health later in life. The relationship between malnutrition and obesity parameters (body mass index [BMI] and waist circumference [WC]) and type 2 diabetes is inconsistent. This study aimed to identify the effects of famine exposure and obesity parameters on type 2 diabetes individually or in combination among middle-aged and older adults in China. Data were extracted from the China Health and Retirement Longitudinal Study Wave1 in 2011. The sample involved 13,065 adults aged 45 to 90. The t- or F test was employed to compare age among groups. The chi-square test was utilized to compare baseline characteristics according to the categorical WC levels/BMI levels/famine exposure and examine between-group differences in type 2 diabetes (diabetes and non-diabetes). Odds ratio (OR) and 95% confidence interval (CI) were estimated by logistic regression models to estimate the individual and combined associations of BMI/WC levels and famine exposure with the prevalence of type 2 diabetes. In this study, 1559 (11.93%) individuals were exposed to Chinese famine during their fetal stage, 5132 (39.28%) and 4428 (33.89%) in childhood and adolescence/adulthood, respectively. Among BMI measurements, 3780 (28.93%) were overweight, and 1487 (11.38%) were obese, whereas WC measurements showed that 5408 (41.39%) were obesity. In addition, 831 (45.48%) males and 996 (54.52%) females reported type 2 diabetes. In multivariable-adjusted regression models, obesity parameters and famine exposure were independently associated with type 2 diabetes prevalence among all participants (P < .001). In the interaction analysis, there existed a trend of higher odds for prevalence of type 2 diabetes across all groups compared to the combination of no-exposed and normal BMI/WC level group (the most increase in odds, adolescence/adulthood-exposed group with central obesity in WC levels: OR 4.51 (95% CI = 3.42–5.95); adolescence/adulthood-exposed group with obesity in BMI levels: OR 5.84 (95% CI = 4.11–8.30; P for interaction <.001). The findings for females exhibited similar to the overall participants, when by gender stratification. Our results suggest famine exposure and obesity parameters have positive combined effects on type 2 diabetes in middle-aged and older adults in China.

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“…However, combining pre- and post-famine births will not always fix the problem because the age difference cannot be balanced out in some studies ( Figure 3A and 4 ). 57,59,61 This can lead to biased study results.…”

Section: Discussionmentioning

confidence: 99%

“…This yielded 23 Chinese famine studies on T2D meeting the inclusion criteria. 25,27,30,31,35,[39][40][41][42][43][49][50][51][52][53][54][55][56][57][58][59][60][61] Table 1 summarizes their selected characteristics: authors, language, data source, outcome assessment, control selection, and reported results. Fourteen of these studies were in English, and the rest were in Chinese.…”

Section: Study Characteristicsmentioning

confidence: 99%

Early-life exposure to the Chinese famine of 1959-61 and type 2 diabetes in adulthood: a systematic review and meta-analysis

Lumey

2022

Preprint

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Background The Chinese famine of 1959-61 has been widely interpreted as an important driver of current and future type 2 diabetes (T2D) epidemics. We conducted a systematic review and meta-analysis of prenatal famine exposure and type 2 diabetes (T2D) in China to summarize study characteristics, examine impacts of control selections and other selected characteristics on study results, identify other characteristics influencing results, and formulate recommendations for future studies. Methods We searched English and Chinese databases for studies that examined the relationship between T2D and prenatal exposure to the Chinese famine up to February 8th, 2022. From included studies, we extracted information on the number of T2D cases and populations at risk among individuals born during the famine (famine births), before the famine (pre-famine births), and after the famine (post-famine births). We compared the risk of T2D in famine births to different controls: post-famine births, pre- and post-famine births combined, and pre-famine births. Heterogeneity across studies was assessed, and random-effects models were used to calculate summary estimates. Meta-regressions were used to examine the relationship between effect estimates and age differences. Subgroup analyses were performed based on selected characteristics, including participants' sex, age, T2D measurement, famine intensity, residence, and publication language. Findings In total, 23 studies met our inclusion criteria. Sample sizes ranged from below 300 to over 350,000. All studies defined famine exposure based on participants' date of birth, and 18 studies compared famine births to controls of post-famine births to estimate famine effects on T2D. Famine and post-famine births had an age difference of three years and over in each study. Using post-famine births as controls, a random-effects model shows an increased risk of T2D (OR 1.50, 95% CI 1.34-1.68) among famine births. In contrast, a marginally increased risk of T2D (OR 1.12, 95% CI 1.02-1.24) can be observed using pre- and post-famine births combined as controls, and a decreased risk (OR 0.89, 95% CI 0.79-1.00) using pre-famine births as controls. Studies with larger age differences between comparison groups had larger famine effects. Effect estimates comparing famine births to pre- and post-famine births combined depend on none of above selected characteristics. Studies showed a large variation in sampling sources, famine intensity assessment, and confounding adjustment. Interpretation Current estimates of a positive relation between prenatal exposure to the Chinese famine and adult T2D are mainly driven by uncontrolled age differences between famine births and post-famine controls. Marginal or no effects remain after controlling for the differences in most Chinese famine studies. It remains an open question to what extent the famine is related to current T2D patterns in China. Studies with more rigorous methods including age-balanced controls and robust famine intensity measures will be needed to quantify this relationship. Funding None.

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Combined effects of air pollution in adulthood and famine exposure in early life on type 2 diabetes

Cited by 3 publications

References 53 publications

Early-Life Exposure to the Chinese Famine of 1959–1961 and Type 2 Diabetes in Adulthood: A Systematic Review and Meta-Analysis

Early-Life Exposure to the Chinese Famine of 1959–1961 and Type 2 Diabetes in Adulthood: A Systematic Review and Meta-Analysis

Individual and combined effects of famine exposure and obesity parameters on type 2 diabetes in middle-aged and older adults: A population-based cross-sectional study

Early-life exposure to the Chinese famine of 1959-61 and type 2 diabetes in adulthood: a systematic review and meta-analysis

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