Exposure to Chinese Famine in Fetal Life and the Risk of Dysglycemiain Adulthood

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.

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.

Is it just a cure? Re-evaluating the effects of prenatal exposure to the Great Chinese Famine on the risk of infectious diseases in adulthood

BACKGROUND

Very limited studies focused on the early-life adversities on infectious diseases. Taking the Great Chinese famine as a natural experiment, this study re-evaluated the long-term effect of prenatal famine exposure on infectious diseases by using nationally representative data.

METHODS

Using difference-in-difference (DID) models, we analyzed 215,216 adults who participated in the Second National Sample Survey on Disability in 2006 across 734 counties of China to detect the effects of prenatal exposure to the Great Chinese Famine on the risk of infectious diseases in adulthood. Infectious diseases were ascertained by using the combination of self-reports or family members' reports and on-site medical diagnosis by experienced specialists, and the severity of famine was measured by the cohort size shrinkage index (CSSI) at the county level.

RESULTS

All DID estimates of the effects of famine on the probability of infectious diseases were insignificant, with a coefficient of 0.0007 (-0.0024, 0.0026) for all participants and coefficients of 0.0001 (-0.0041, 0.0043) and -0.0002 (-0.0036, 0.0033) for males and females, respectively. That is, the famine cohort dwelling in regions with a greater intensity of famine had similar levels of infectious disease risks than the cohorts with post-famine prenatal exposure experience in less affected famine regions. Furthermore, there were no significant famine and post-famine cohort differences in the DID estimates by examining the variations in subgroups with different types of infectious diseases (trachoma, poliomyelitis, tuberculosis, maternal infections and other infectious diseases).

CONCLUSION

No significant impact of prenatal exposure to the Chinese famine was observed on the risk of infectious diseases in adulthood. Famine survivors may be "cured" by the famine and were resilient to adverse environments in their life course because selective mortality may weaken the association between adverse prenatal exposure and later health.

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.

Sex Differences at Early Old Stage in Glycolipid Metabolism and Fatty Liver in Offspring Prenatally Exposed to Chinese Great Famine

Background

About 50 years ago, Chinese Great Famine (CGF) affected the entire population in China, and its long-term influence on the offspring has attracted significant attention for research. However, information on possible metabolic differences between sexes is limited. This study explored whether there might be sex differences in the risks of development of glucolipid metabolic dysfunction and fatty liver following prenatal exposure to CGF.

Materials and Methods

There were 11,417 subjects around 55 years of age (6,661 women and 4,756 men). They were divided as the exposed group in which the fetal stage was in CGF, and the unexposed group included those born after CGF. Analysis focused on comparisons between sexes.

Results

Compared to the unexposed group, the BMI and triglyceride (P &lt; 0.05) in men were higher in exposed group, while waist circumference and blood sugar (P &lt; 0.05) in the exposed women were significantly higher. With the ages being properly balanced, the risks of glycolipid metabolic dysfunction were significantly higher in both men and women in the exposed than in the unexposed group (P &lt; 0.001). Prenatal exposure to CGF significantly increased risks of abnormal BMI (P &lt; 0.001, 95% CI: 2.305–2.93), blood sugar (P &lt; 0.05, 95% CI: 1.050–1.401), triglycerides (P &lt; 0.05, 95% CI: 1.006–1.245), and fatty liver (P &lt; 0.001, 95% CI: 1.121–1.390) in men, and increased risks of abnormal blood sugar (P &lt; 0.05, 95% CI: 1.024–1.689) and positive urine sugar (P &lt; 0.05, 95% CI: 1.062–6.211) in women. Height and body weight were either the same or higher in the exposed subjects compared with the unexposed ones, regardless of sexes.

Conclusion

This study is the first to identify sex differences in the long-term effects of CGF on metabolism and fatty liver. Importance of the findings include the benefits of prescribing medicine for the early prevention of certain diseases for each sex before aging based on the differences revealed. This study also shows “catch-up growth” in the offspring prenatally exposed to CGF as possible mechanisms underlying the long-term effects.