Early-life exposure to the Chinese famine, genetic susceptibility and the risk of type 2 diabetes in adulthood

Famine mortality and contributions to later-life type 2 diabetes at the population level: a synthesis of findings from Ukrainian, Dutch and Chinese famines

Since the 1970s, influential literature has been using famines as natural experiments to examine the long-term health impact of prenatal famine exposure at the individual level. Although studies based on various famines have consistently shown that prenatal famine exposure is associated with an increased risk of type 2 diabetes (T2D), no studies have yet quantified the contribution of famines to later-life T2D at the population level. We, therefore, synthesised findings from the famines in Ukraine 1932-1933, the Western Netherlands 1944-1945 and China 1959-1961 to make preliminary estimates of T2D cases attributable to prenatal famine exposure. These famines were selected because they provide the most extensive and reliable data from an epidemiological perspective. We observed a consistent increase in T2D risk among prenatally exposed individuals in these famines, which translated into about 21 000, 400 and 0.9 million additional T2D cases due to prenatal famine exposure in Ukraine, Western Netherlands and China, respectively. The T2D increase related to famine exposure represented only around 1% of prevalent T2D cases in these countries. Our observations highlight the significant increase in later-life T2D risk among individuals with prenatal famine exposure but also the limited contribution of prenatal famine exposure to T2D epidemics at the population level.

Genetic predisposition to impaired beta-cell function modifies the association between serum pyrethroid levels and the risk of type 2 diabetes: A gene-environment interaction study

Previous studies suggested that pyrethroid exposure was associated with elevated type 2 diabetes (T2D) risk, while it remains uncertain whether genetic predisposition modifies this association. A nested case-control study within the prospective Dongfeng-Tongji cohort comprised 1832 T2D cases, age- (±5 years) and sex-matched controls with qualified genotyping data. Serum pyrethroids were measured by gas chromatography-tandem mass spectrometry. Overall diabetes-related genetic risk score (GRS) or pathway-specific GRS, including unweighted GRSs (uGRS) and weighted GRSs (wGRS), was developed by genetic variants identified in Asian populations. Higher overall diabetes-related GRS and GRS specific to the pathway of impaired beta cell function (Beta-cell GRS) were associated with a higher incident T2D risk. Beta-cell uGRS significantly modified the association of serum permethrin (Pinteraction=0.04) and deltamethrin (Pinteraction=0.01) with T2D. Specifically, for each doubling increase in serum deltamethrin, the odds ratios (ORs) (95 % confidence intervals [CIs]) for T2D were 1.23 (0.98-1.56) and 0.91 (0.77-1.07) in the highest and lowest Beta-cell uGRS group, as well as 1.23 (1.02-1.47) and 0.95 (0.78-1.15) for Beta-cell wGRS group, respectively. When considering jointly, those with the highest deltamethrin levels and highest Beta-cell GRS had a substantially higher T2D risk, compared with the reference group (OR for uGRS: 3.79 [95 % CI: 2.03-7.07], Pinteraction=0.03 and 3.23 [95 % CI: 1.78-5.87], Pinteraction=0.05 for wGRS). Our findings suggested that genetic susceptibility to impaired beta-cell function should be considered for T2D prevention targeting pyrethroid exposure, particularly deltamethrin.

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

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.

The effects of vitamin D and gene polymorphisms on susceptibility to thyroid peroxidase antibody positivity

BACKGROUND

The etiology of Hashimoto's thyroiditis (HT) involves genetic and environmental factors. There is a lack of clarity regarding the relationship between Vitamin D and HT. This study aimed to investigate the effect of Vitamin D and gene polymorphisms on thyroid peroxidase antibody (TPOAb) positivity.

METHODS

A total of 9,966 participants were included from a survey conducted in East China from 2014 to 2016. We measured the levels of 25(OH)D, thyroid hormones and autoimmune antibodies. rs11675434, rs9277555, and rs301799 were genotyped. Based on these 3 SNPs, a weighted genetic risk score was calculated for TPOAb.

RESULTS

The proportion of females in the TPOAb-positive group was greater than that in the TPOAb-negative group (74.2% vs. 57.2%, P<0.001). Vitamin D levels were lower in the TPOAb-positive group than in the TPOAb-negative group (40.07±11.87 vs. 40.80±12.84, P=0.01). The GG genotype of rs9277555 and the TT genotype of rs11675434 were correlated with the risk of TPOAb positivity (OR=1.34, 95% CI 1.13-1.59, P=0.001; OR=1.29, 95% CI 1.06-1.58, P=0.01). TPOAb-GRS was associated with TPOAb positivity (OR=3.17, 95% CI 1.72-5.84; P<0.001). When stratified by Vitamin D group, the association between TPOAb-GRS and TPOAb positivity existed only in the Vitamin D deficiency group (OR=3.41, 95% CI 1.73-6.70 P<0.001) but not in the control group (OR=2.45, 95% CI 0.59-10.19, P=0.22).

CONCLUSIONS

This study suggested that TPOAb-GRS was associated with TPOAb positivity in the Han Chinese population, mainly due to rs9277555 and rs11675434. The hereditary effect of TPOAb positivity differed depending on Vitamin D status.

Associations of concurrent early-life famine exposure and adulthood obesity with type 2 diabetes mellitus in middle-aged Chinese

BACKGROUND

Evidence has shown that early-life famine exposure and obesity in adulthood are independently associated with the risk of type 2 diabetes mellitus (T2DM). However, few studies had revealed the combined effect of these risk factors.

METHODS

Two sets of groups from the China Health and Retirement Longitudinal Study (CHARLS) were selected. The fetal-exposure group born in 1959-1961 from 2011 wave (N = 958) and nonexposure group born in 1963-1965 from 2015 wave (N = 1540) were selected as Comparison 1. The early childhood-exposure group born in 1955-1957 from 2011 wave (N = 1510) and fetal-exposure group born in 1959-1961 from 2015 wave (N = 943) were Comparison 2. Logistic regressions were applied to examine the associations of different famine exposure periods and obesity patterns with T2DM risk.

RESULTS

Compared with nonexposed participants without central overweight/obesity in adulthood, central overweight/obesity in adulthood together with nonexposure (odds ratio [OR]: 1.89, 95% confidence interval [CI]: 1.19-3.00) or fetal-exposure (OR: 1.99, 95% CI: 1.23-3.23) was associated with higher risks of T2DM. Compared with the early childhood-exposure group, the fetal-exposed participants showed higher risks of T2DM (OR: 1.30, 95% CI: 1.02-1.66). The coexistence of fetal famine exposure and central overweight/obesity in adulthood was associated with higher risks of T2DM (OR: 1.82, 95% CI: 1.19-2.79). Consistent associations were observed among males and participants from less severely affected areas.

CONCLUSIONS

In conclusion, central overweight/obesity in adulthood is associated with the increased risk of T2DM, but the effect of early-life famine exposure is not very clear.

Mitochondrial dysfunction and epigenetics underlying the link between early-life nutrition and non-alcoholic fatty liver disease

Early-life malnutrition plays a critical role in foetal development and predisposes to metabolic diseases later in life, according to the concept of 'developmental programming'. Different types of early nutritional imbalance, including undernutrition, overnutrition and micronutrient deficiency, have been related to long-term metabolic disorders. Accumulating evidence has demonstrated that disturbances in nutrition during the period of preconception, pregnancy and primary infancy can affect mitochondrial function and epigenetic mechanisms. Moreover, even though multiple mechanisms underlying non-alcoholic fatty liver disease (NAFLD) have been described, in the past years, special attention has been given to mitochondrial dysfunction and epigenetic alterations. Mitochondria play a key role in cellular metabolic functions. Dysfunctional mitochondria contribute to oxidative stress, insulin resistance and inflammation. Epigenetic mechanisms have been related to alterations in genes involved in lipid metabolism, fibrogenesis, inflammation and tumorigenesis. In accordance, studies have reported that mitochondrial dysfunction and epigenetics linked to early-life nutrition can be important contributing factors in the pathogenesis of NAFLD. In this review, we summarise the current understanding of the interplay between mitochondrial dysfunction, epigenetics and nutrition during early life, which is relevant to developmental programming of NAFLD.

Effect modification of socioeconomic status on the association of exposure to famine in early life with osteoporosis in women

BACKGROUND

The present study aimed to explore the effect of modification of socioeconomic status (SES) on the association between famine exposure in early life and osteoporosis in adulthood via the baseline data from the Henan Rural cohort study.

METHODS

A total of 2669 exposed to famine participants were selected from the Henan Rural cohort, and the questionnaires, physical examination and bone mineral density measurement were completed. Specific birth years were used to define five groups: the fetal exposed group, early-childhood exposed group, mid-childhood exposed group, late-childhood exposed group and unexposed group. And the age-matched control group was a combination of the unexposed group and late-childhood exposed group. Multivariable logistic regression models were utilised to analyse the association of famine exposure in early life with osteoporosis in adulthood.

RESULTS

The prevalence rates of osteoporosis of participants exposed to famine during the fetal period, early-childhood, mid-childhood and the age-matched group were 21.67%, 25.76%, 23.90% and 18.14%, respectively. The adjusted odds ratios (95% confidence interval) of participants suffering from famine during the fetal period, early-childhood and mid-childhood versus age-matched group were 1.19 (0.82-1.73), 1.40 (1.04-1.88) and 1.57 (1.16-2.13), respectively. The female participants yielded consistent results. The risk of osteoporosis was higher in more severe famine eara. Moreover, an attenuated effect of early life famine exposure on osteoporosis was observed in female participants with high SES.

CONCLUSIONS

Exposure to famine in early life showed a sex-specific association with an increased risk of osteoporosis in adulthood and the severity of famine may exacerbate this association. In addition, the risk could be modified by SES.

Long-term effect of styrene and ethylbenzene exposure on fasting plasma glucose: A gene-environment interaction study

Styrene and ethylbenzene (S/EB) are hazardous pollutants that have attracted worldwide concern. In this prospective cohort study, S/EB exposure biomarker (the sum of mandelic acid and phenylglyoxylic acid [MA+PGA]) and fasting plasma glucose (FPG) were repeatedly measured three times. The polygenic risk score (PRS) based on 137 single nucleotide polymorphisms for type 2 diabetes mellitus (T2DM) was calculated to evaluate cumulative genetic effect. In repeated-measures cross-sectional analyses, MA+PGA (β [95% confidence interval]: 0.106 [0.022, 0.189]) and PRS (0.111 [0.047, 0.176]) were significantly related to FPG. For long-term effect assessment, participants with sustained high MA+PGA or with high PRS had 0.021 (95% CI: -0.398, 0.441) or 0.465 (0.064, 0.866) mmol/L increase in FPG, respectively, over 3 years follow-up, and had 0.256 (0.017, 0.494) or 0.265 (0.004, 0.527) mmol/L increase in FPG, respectively, over 6 years follow-up. We further detected a significant interaction effect between MA+PGA and PRS on FPG change, compared with participants with sustained low MA+PGA and low PRS, those with sustained high MA+PGA and high PRS had 0.778 (0.319, 1.258) mmol/L increase in FPG (P for interaction=0.028) over 6 years follow-up. Our study provides the first evidence that long-term exposure to S/EB potentially increases FPG, which might be aggravated by genetic susceptibility.

Effects of fetal famine exposure on the cardiovascular disease risk in the metabolic syndrome individuals

BACKGROUND

Patients with metabolic syndrome (MS) have a higher incidence of cardiovascular disease (CVD), but the possible mechanisms are not fully understood and further exploration of the possible factors influencing the high incidence of CVD in patients with MS is still needed.

OBJECTIVES

This study aims to examine the association between fetal famine exposure and the risk of CVD in adulthood with MS.

METHODS

Of 13,744 MS patients free of CVD selected from the Kailuan Study in 2006 (referred as the baseline survey) were included in the study. China suffered a severe famine from 1959 to 1962, so the participants born during this period were classified as the uterine famine exposed group. All patients were born between January 1, 1949, and December 31, 1974. Based on the date of birth, all patients were divided into the no-exposed group (born between January 1, 1963, and December 31, 1974), uterine famine exposed group (born between January 1, 1959 and December 31, 1962), and childhood famine exposed group (born between January 1, 1949 and December 31, 1958). After following up to December 31, 2019, the weighted Cox regression analysis model was used to calculate the effect of early life famine exposure in MS individuals on the risk of CVD in adulthood.

RESULTS

During the 12.12 years of follow-up, the incidence of CVD was 5.87%, 10.13%, and 10.90% in the no-exposed group, uterine famine exposed group, and childhood famine exposed group, respectively. Compared with participants in the no-exposed group, the CVD risk and stroke risk increased in participants in the uterine famine exposed group (for CVD, HR: 1.32, 95% CI 1.04-1.67; for stroke, HR:1.37, 95% CI 1.05-1.79), but not in childhood famine exposed group. However, the increased CVD risks were only observed in females or smokers. No increased MI risks were observed for participants in the uterine famine exposed group or childhood famine exposed group.

CONCLUSIONS

Our findings suggested that exposure to famine during uterine life might increase the risk of CVD in adulthood in participants with MS.

Effect of foetal exposure to famine on the risk of nonalcoholic fatty liver disease in adulthood: A systematic review and meta-analysis

OBJECTIVE

The risk of metabolic disease in adulthood is not only attributed to an unhealthy lifestyle after birth but also to famine exposure during the foetal period. This systematic review and meta-analysis aimed to evaluate the effects of foetal exposure to famine as a risk factor for developing nonalcoholic fatty liver disease (NAFLD) in adulthood.

METHODS

Studies were retrieved from PubMed, Embase, Cochrane Library, Web of Science, China National Knowledge Infrastructure (CNKI), and Wanfang databases to evaluate the effect of foetal exposure to famine on the risk of nonalcoholic fatty liver disease in adulthood.

RESULTS

Six studies involving 90,582 subjects were included in this meta-analysis. Foetal exposure to famine was associated with an increased risk of NAFLD(RR = 1.17, 95% CI: 1.08-1.27, P < 0.0001). Exposure to famine during the foetal period significantly increased the incidence of NAFLD in women (RR = 1.27, 95% CI: 1.16-1.40, P <0.00001), while similar results were not observed in the male subgroup (RR =0.99, 95% CI: 0.89-1.11, P = 0.88). Foetal exposure to famine was associated with the risk of mild NAFLD (RR = 1.17, 95% CI: 1.02-1.33, P = 0.02) and moderate to severe NAFLD (RR = 1.51, 95% CI: 1.16-1.98, P = 0.002).

CONCLUSIONS

Foetal exposure to famine is associated with an increased risk of NAFLD in adulthood. Women with NAFLD and moderate to severe NAFLD have a more robust association with foetal exposure to famine.

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

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.

Early life programming of health and disease: the long-term consequences of obesity in pregnancy: a narrative review

The prevalence of overweight and obesity is rising in all parts of the world and among young women it presents a very clear danger during pregnancy. Women who are overweight or who gain excessive weight during pregnancy are at greater risk of complications in pregnancy and labour, and are more likely to lose their child to stillbirth, or themselves die during pregnancy. This narrative review considers the evidence that in addition to increasing risk of poor pregnancy outcomes, obesity has the capacity to programme fetuses to be at greater risk of cardiometabolic disorders later in life. An extensive body of evidence from prospective and retrospective cohorts, and record linkage studies demonstrates associations of maternal obesity and/or gestational diabetes with cardiovascular disease, type-1 and type-2 diabetes. Studies in animals suggest that these associations are underpinned by adaptations that occur in fetal life, which remodel the structures of major organs including the brain, kidney and pancreas. This article is protected by copyright. All rights reserved.

Association of Parental Famine Exposure With Offspring Depression and Cognition Function

BACKGROUND

The effect of early exposure to famine on depression and cognition in adulthood has been shown, but the intergenerational association of famine remain to be explored. This study focused on exploring the association of parental famine exposure with depression and cognition in the offspring.

METHODS

Based on the Chinese Family Panel Studies database, which is a longitudinal survey, we included 5,150 individuals born between 1959 and 1961 and divided them into fetal-exposed, infancy-exposed (birth year = 1957-1958), school-age-exposed (birth year = 1949-1956), adolescent-exposed (birth year = 1946-1948), and unexposed groups. We used one-way analysis of variance, multiple linear regression, and one follow-up measurement to analyze the association between parental famine exposure and offspring depression and cognitive function.

RESULTS

Compared with the unexposed group, the correlations between parental famine exposure during fetal period and their cognitive function (mother: β = -1.614, 95% CI: -2.535, -0.693; p = 0.001; father: β = -2.153, 95% CI: -3.104, -1.202, p < 0.001) were significant. For the offspring, there was a negative correlation between famine exposure of fathers during the fetal period and depression in their offspring (β = -0.477, 95% CI: -0.907, -0.047; p = 0.030). There was a negative correlation between maternal famine exposure during the infant and adolescent period and cognitive function in the offspring (math test: β = -0.730, 95% CI: -1.307, -0.153; p = 0.013; word test: β = -2.346, 95% CI: -4.067, -0.625; p = 0.008).

LIMITATIONS

Not all variables related to depression and cognition function were included in the CFPS database, and the other unknown or unmeasured confounders may explain our results.

Early-Life Exposure to Famine and Risk of Metabolic Associated Fatty Liver Disease in Chinese Adults

Background: Early-life exposure to the Chinese famine has been related to the risk of obesity, type 2 diabetes, and nonalcoholic fatty liver disease later in life. Nevertheless, the long-term impact of famine exposure on metabolic associated fatty liver disease (MAFLD), a recently proposed term to describe liver disease associated with known metabolic dysfunction, remains unknown. The aim of our study was to explore the relationship between early famine exposure and MAFLD in adulthood. Methods: A total of 26,821 participants (10,994 men, 15,827 women) were recruited from a cohort study of Chinese adults in Shanghai. We categorized participants into four famine exposure subgroups based on the birth year as nonexposed (1963–1967), fetal-exposed (1959–1962), childhood-exposed (1949–1958), and adolescence-exposed (1941–1948). MAFLD was defined as liver steatosis detected by ultrasound plus one of the following three criteria: overweight/obesity, type 2 diabetes, or evidence of metabolic dysregulation. Multivariable logistic regression models were performed to examine the association between famine exposure and MAFLD. Results: The mean ± standard deviation age of the participants was 60.8 ± 6.8 years. The age-adjusted prevalence of MAFLD was 38.3, 40.8, 40.1, and 36.5% for the nonexposed, fetal-exposed, childhood-exposed, and adolescence-exposed subgroups, respectively. Compared with nonexposed participants, fetal-exposed participants showed an increased risk of adulthood MAFLD (OR = 1.10, 95% CI 1.00–1.21). The significant association between fetal famine exposure and MAFLD was observed in women (OR = 1.22, 95% CI 1.08–1.37), but not in men (OR = 0.88, 95% CI 0.75–1.03). In age-balanced analyses combining pre-famine and post-famine births as the reference, women exposed to famine in the fetal stage still had an increased risk of MAFLD (OR = 1.15, 95% CI 1.05–1.26). Conclusions: Prenatal exposure to famine showed a sex-specific association with the risk of MAFLD in adulthood.