Paternal insulin resistance and its association with umbilical cord insulin concentrations

Two decades since the fetal insulin hypothesis: what have we learned from genetics?

In 1998 the fetal insulin hypothesis proposed that lower birthweight and adult-onset type 2 diabetes are two phenotypes of the same genotype. Since then, advances in research investigating the role of genetics affecting insulin secretion and action have furthered knowledge of fetal insulin-mediated growth and the biology of type 2 diabetes. In this review, we discuss the historical research context from which the fetal insulin hypothesis originated and consider the position of the hypothesis in light of recent evidence. In summary, there is now ample evidence to support the idea that variants of certain genes which result in impaired pancreatic beta cell function and reduced insulin secretion contribute to both lower birthweight and higher type 2 diabetes risk in later life when inherited by the fetus. There is also evidence to support genetic links between type 2 diabetes secondary to reduced insulin action and lower birthweight but this applies only to loci implicated in body fat distribution and not those influencing insulin resistance via obesity or lipid metabolism by the liver. Finally, we also consider how advances in genetics are being used to explore alternative hypotheses, namely the role of the maternal intrauterine environment, in the relationship between lower birthweight and adult cardiometabolic disease.

Paternal metabolic and cardiovascular programming of their offspring: A systematic scoping review

BACKGROUND

There is lots of evidence that maternal peri-gestational metabolic, genomic and environmental conditions are closely linked to metabolic and cardiovascular outcomes in their offspring later in life. Moreover, there is also lotsof evidence that underlining mechanisms, such as molecular as well as epigenetic changes may alter the intrauterine environment leading to cardio-metabolic diseases in their offspring postnatal. But, there is also increasing evidence that cardio-metabolic diseases may be closely linked to their paternal metabolic risk factors, such as obesity, Type 2 Diabetes and other risk factors.

OBJECTIVE

To analyse the evidence as well as specific risk factors of paternal trans-generational programming of cardio-metabolic diseases in their offspring.

METHODS

Within a systematic scoping review, we performed a literature search in MEDLINE (PubMed) and EMBASE databases in August 2020 considering original research articles (2000-2020) that examined the impact of paternal programming on metabolic and cardiovascular offspring health. Epidemiological, clinical and experimental studies as well as human and animal model studies were included.

RESULTS

From n = 3.199 citations, n = 66 eligible studies were included. We selected n = 45 epidemiological as well as clinical studies and n = 21 experimental studies. In brief, pre-conceptional paternal risk factors, such as obesity, own birth weight, high-fat and low-protein diet, undernutrition, diabetes mellitus, hyperglycaemia, advanced age, smoking as well as environmental chemical exposure affect clearly metabolic and cardiovascular health of their offspring later in life.

CONCLUSIONS

There is emerging evidence that paternal risk factors, such as paternal obesity, diabetes mellitus, nutritional habits, advanced age and exposure to environmental chemicals or cigarette smoke, are clearly associated with adverse effects in metabolic and cardiovascular health in their offspring. Compared to maternal programming, pre-conceptional paternal factors might also have also a substantial effect in the sense of trans-generational programming of their offspring and need further research.

Maternal and paternal histories differentially influence risks for diabetes, insulin secretion and insulin resistance in a Chinese population

Aims/Introduction

To investigate the differential effects of maternal versus paternal history of diabetes on the risks for diabetes and prediabetes, as well as on insulin secretion and resistance in Chinese individuals.

Materials and Methods

From the 2007 to 2008 China National Diabetes and Metabolism Disorders Study, 39,244 participants were included and divided into four categories: negative parental history, paternal history only (PH), maternal history only (MH), and both paternal and maternal history.

Results

The age‐ and sex‐standardized prevalence rates of diabetes in the negative parental history, PH, MH, and both paternal and maternal history groups were 8.59, 12.56, 15.86 and 29.81%, respectively. The prevalence rates of impaired glucose metabolism were 24.13, 25.41, 31.13 and 50.80%, with the prevalence in the MH group being significantly higher than that in the PH group. Compared with that in the FH0 group, the risks of diabetes in the PH, MH, and both paternal and maternal history groups were 2.01‐, 2.67‐ and 6.37‐fold greater, and the risks of impaired glucose metabolism were 1.28‐, 1.65‐ and 3.45‐fold greater. In addition, MH had a significantly greater impact on impaired glucose metabolism than PH (P_MHvsPH = 0.0292). Regression analyses suggested MH was associated with homeostatic model assessment for β‐cell function (β[SE] = −0.0910[0.0334], P = 0.0065), insulinogenic index (−0.1866[0.0550], P = 0.0007), homeostatic model assessment for insulin resistance (0.0662[0.0227], P = 0.0036) and Matsuda Index [−0.0716(0.0203), P = 0.0004]. PH was specifically associated with homeostatic model assessment for insulin resistance (0.1343[0.0267], P < 0.0001) and Matsuda Index (−0.1566[0.0243], P < 0.0001), but the effects were stronger than those of MH (P_MHvsPH = 0.0431, 0.0054).

Conclusions

MH and PH differentially influence the risks for diabetes, insulin secretion, and insulin resistance in the Chinese population, suggesting they participate in the pathogenesis of diabetes through different mechanisms.

Associations of cord leptin and cord insulin with adiposity and blood pressure in White British and Pakistani children aged 4/5 years

Background: Cord leptin and cord insulin concentrations may be important biomarkers of child adiposity and cardiovascular health, especially in populations with an increased long-term risk of type 2 diabetes and cardiovascular diseases. We aimed to determine whether cord leptin and insulin are associated with adiposity and early cardiovascular health at age 4/5, and whether any associations differ between White British and Pakistani children. Methods: Using bi-ethnic cohort data from 6060 mother-offspring pairs (2717 (44.8%) White British, 3343 (55.2%) Pakistani), we examined associations of cord leptin and insulin with adiposity (BMI, skinfold thickness) and systolic and diastolic blood pressure at age 4/5. Results: Cord leptin and insulin were higher in Pakistani compared to White British children (7.4 ng/ml versus 6.7 ng/ml and 4.1 mU/L versus 3.63 mU/L , respectively). Associations with adiposity measurements were similar in both groups and close to the null value. For example, each 10 ng/ml higher cord leptin was associated with a difference in mean childhood BMI of 0.10 kg/m 2 (95% CI 0.01, 0.19) in White British, 0.01 kg/m 2 (95% CI -0.08, 0.10) in Pakistani and 0.04 kg/m 2 (95% CI -0.02, 0.11) in both groups combined.  Associations with systolic and diastolic blood pressure were also close to the null and consistent in both groups. Conclusions: We found no evidence that cord leptin or insulin were likely to be valuable biomarkers for predicting later adiposity and blood pressure in White British or Pakistani children. For now, other factors such as family history and social-economic status may be more useful markers of risk.

Genetic influences on the association between fetal growth and susceptibility to type 2 diabetes

The fetal insulin hypothesis proposes that low birth weight and susceptibility to type 2 diabetes (T2D) could both be two phenotypes of the same genotype. Insulin is a key growth factor in utero, and T2D is characterized by insulin resistance and/or beta-cell dysfunction. Therefore, genetic variants impacting on insulin secretion and action are likely to alter both fetal growth and susceptibility to T2D. There are three lines of evidence in support of this hypothesis. (1) Studies of rare monogenic diabetes have shown mutations in a single gene, such as GCK or KCNJ11, can cause diabetes by reducing insulin secretion, and these mutations are also associated with reduced birth weight. (2) Epidemiological studies have indicated that children born to fathers with diabetes are born smaller. As the father cannot influence the intrauterine environment, this association is likely to reflect genes inherited by the fetus from the father. (3) The most compelling evidence comes from recent genome-wide association studies. Variants in the CDKAL1 and HHEX-IDE genes that predispose to diabetes, if present in the fetus, are associated with reduced birth weight. These data provide evidence for a genetic contribution to the association between low birth weight and susceptibility to T2D. This genetic background is important to take into consideration when investigating the impact of environmental determinants and developing strategies for intervention and prevention.

Obese father's metabolic state, adiposity, and reproductive capacity indicate son's reproductive health

OBJECTIVE

To determine whether dietary and exercise regimes in obese males can provide a novel intervention window for improving the reproductive health of the next generation.

DESIGN

Experimental animal study.

SETTING

University research facilities.

ANIMAL(S)

C57BL6 male and female mice.

INTERVENTION(S)

Mice were fed a control diet (6% fat) or high-fat diet (21% fat) for 9 weeks. After the initial feeding, high-fat-diet males were allocated to diet and/or exercise interventions for a further 9 weeks. After intervention males were mated with females fed standard chow (4% fat) before and during pregnancy.

MAIN OUTCOME MEASURE(S)

F1 sperm motility, count, morphology, capacitation, mitochondrial function, and sperm binding and weight of reproductive organs.

RESULT(S)

Our primary finding was that diet intervention alone in founders improved offspring sperm motility and mitochondrial markers of sperm health (decreased reactive oxygen species and mitochondrial membrane potential), ultimately improving sperm binding. Sperm binding and capacitation was also improved in F1 males born to a combined diet and exercise intervention in founders. Founder sperm parameters and metabolic measures as a response to diet and/or exercise (i.e., lipid/glucose homeostasis, sperm count and morphology) correlated with offspring's sperm function, independent of founder treatment. This implicates paternal metabolic and reproductive status in predicting male offspring's reproductive function.

CONCLUSION(S)

This is the first study to show that improvements to both metabolic (lipids, glucose and insulin sensitivity) and reproductive function (sperm motility and morphology) in obese fathers via diet and exercise interventions can improve subsequent reproductive health in offspring.

Paternal metabolic and cardiovascular risk factors for fetal growth restriction: a case-control study

OBJECTIVE

Fathers of low-birth weight offspring are more likely to have type 2 diabetes and cardiovascular disease in later life. We investigated whether paternal insulin resistance and cardiovascular risk factors were evident at the time that fetal growth-restricted offspring were born.

RESEARCH DESIGN AND METHODS

We carried out a case-control study of men who fathered pregnancies affected by fetal growth restriction, in the absence of recognized fetal disease (n = 42), compared with men who fathered normal-birth weight offspring (n = 77). All mothers were healthy, nonsmoking, and similar in age, BMI, ethnicity, and parity. Within 4 weeks of offspring birth, all fathers had measures of insulin resistance (HOMA index), blood pressure, waist circumference, endothelial function (flow-mediated dilatation), lipid profile, weight, and smoking habit. Comparison was made using multivariable logistical regression analysis.

RESULTS

Fathers of fetal growth-restricted offspring [mean (SD) 1.8th (2.2) customized birth centile] were more likely to have insulin resistance, hypertension, central adiposity, and endothelial dysfunction and to smoke cigarettes compared with fathers of normal grown offspring. After multivariable analysis, paternal insulin resistance and smoking remained different between the groups. Compared with fathers of normal grown offspring, men who fathered pregnancies affected by fetal growth restriction had an OR 7.68 (95% CI 2.63-22.40; P < 0.0001) of having a 1-unit higher log HOMA-IR value and 3.39 (1.26-9.16; P = 0.016) of being a smoker.

CONCLUSIONS

Men who recently fathered growth-restricted offspring have preclinical evidence of the insulin resistance syndrome and are more likely to smoke than fathers of normal grown offspring. Paternal lifestyle may influence heritable factors important for fetal growth.

Offspring birth weight and cardiovascular risk in parents: a population-based HUNT 2 study

Low birth weight is associated with increased risk of cardiovascular disease and type 2 diabetes in later life. The fetal insulin hypothesis suggests that shared genetic factors partly explain this association. If fetal genes predispose to both low birth weight and cardiovascular disease in adulthood, fathers of offspring with low birth weight should display an unfavorable profile of cardiovascular risk factors. To study this, the authors linked data on more than 14,000 parents, collected from the second Health Study of Nord Trøndelag County, Norway (HUNT 2, 1995-1997), to offspring data from the Norwegian Medical Birth Registry (1967-2005). Linear regression was used to study associations of offspring birth weight for gestational age with the parents' body mass index, waist circumference, blood pressure, glucose, and serum lipids. All analyses were adjusted for shared environment by means of the socioeconomic measures, lifestyle, and cardiovascular risk factors of the partner. The authors found that low offspring birth weight for gestational age was associated with increased paternal blood pressure, body mass index, waist circumference, and unfavorable levels of glucose and lipids. For mothers, associations similar to those for fathers were found for blood pressure, whereas associations in the opposite direction were found for glucose, lipids, and body mass index. The paternal findings strengthen the genetic hypothesis.

Effect of paternal diabetes on pre-diabetic phenotypes in adult offspring

OBJECTIVE

Paternal and maternal type 2 diabetes, exclusive of gestational diabetes, may influence risk factors in the offspring differently (through possible epigenetic effects of parental diabetes) and are difficult to identify without accurate dates of diagnosis. We aimed to examine a metabolic phenotype in three different groups of offspring to see distinct paternal versus maternal effects.

RESEARCH DESIGN AND METHODS

We examined body composition and insulin action (M) in nondiabetic subjects and insulin secretion tested via acute insulin response (AIR) in normal glucose-tolerant full-heritage Pima Indian adults categorized by disparate parental diabetes status: 1) offspring of fathers with early-onset diabetes (age <35 years) and nondiabetic mothers (ODF; n = 10), 2) offspring of mothers with early-onset diabetes (age <35 years), not exposed to diabetes in utero with nondiabetic fathers (OMED; n = 11), and 3) a control group of offspring of parents without diabetes until >50 years of age (CON; n = 15).

RESULTS

ODFs were leaner than CONs and OMEDs (percent of body fat [%BF]: least-squares means adjusted for age and sex [95% CI]: 27.3 [23.3-31.3] in ODFs vs. 35.4 [32.2-38.5] in CONs and 32.4 [28.8-36.1] in OMEDs, P = 0.04). ODFs were more insulin sensitive (had a higher M) than OMEDs or CONs, but not after adjustment for age, sex, and %BF. AIR adjusted for M, age, sex, and %BF was lower in ODFs versus CONs and OMEDs (P < 0.05).

CONCLUSIONS

Adult ODFs were leaner and had lower early insulin secretion, despite being equally insulin sensitive after adjustment for body fat compared to the other groups, indicating a paternal imprinted effect.

Familial (shared environmental and genetic) factors and the foetal origins of cardiovascular diseases and type 2 diabetes: a review of the literature

Several researchers have argued that observed associations between birth weight and cardiovascular diseases, and type 2 diabetes, may be confounded by familial (shared environmental and genetic) factors. However, most studies have found that shared environmental factors, including socio-economic factors, do not influence the foetal origins of adult diseases. Results from two twin studies suggest that genetic factors may be of importance for the association between birth weight and risks of coronary heart disease, but findings from intergenerational studies are not consistent with genetic confounding. More studies have assessed the importance of genetic factors with respect to risk factors of coronary heart, including raised blood pressure and lipid levels. Recent findings suggest that the association between birth weight and hypertension is independent of genetic factors. In contrast, recent twin and intergenerational studies favour the hypothesis that the association between birth weight and risk of type 2 diabetes is confounded by genetic factors.

Measurement of cord insulin and insulin-related peptides suggests that girls are more insulin resistant than boys at birth

OBJECTIVE

We aimed to examine sex differences in insulin and insulin propeptide concentrations at birth using validated cord blood collection.

RESEARCH DESIGN AND METHODS

We tested the impact on insulin and insulin propeptides of taking 13 cord blood samples in heparin and EDTA and then centrifuging and separating plasma after 1, 2, 24, or 48 h at room temperature (heparin) or 4 degrees C (EDTA). Cord plasma insulin and insulin propeptides concentrations were measured in 440 babies and correlated with offspring anthropometry measured at birth.

RESULTS

Cord insulin concentrations significantly decreased (74% those at baseline by 24 h; P = 0.01) in the samples taken in heparin and stored at room temperature, but those taken on EDTA and refrigerated remained stable for up to 48 h. Insulin propeptides were stable in both. Cord plasma insulin and insulin propeptides measured in EDTA were related to all measures of birth size and maternal glycemia and BMI (r > 0.11; P < 0.03 for all) and were higher in those delivered via caesarean section. Girls were lighter (3,497 vs. 3,608 g; P = 0.01) but had higher cord insulin (46.7 vs. 41.2 pmol/l; P = 0.031), total proinsulin (34.1 vs. 25.8 pmol/l; P < 0.001), and intact proinsulin (9.5 vs. 8.3 pmol/l; P = 0.004) concentrations than boys; this was further confirmed when cord insulin concentrations of boys and girls were compared after pair matching for birth weight (insulin 49.7 vs. 42.1 pmol/l; P = 0.004).

CONCLUSIONS

When using appropriate sample collection methods, female newborns have higher insulin concentrations than male newborns, despite being smaller, suggesting intrinsic insulin resistance in girls.

Offspring birthweight is not associated with paternal insulin resistance

AIMS/HYPOTHESIS

Low birthweight is associated with insulin resistance and other insulin resistance-related phenotypes: diabetes, hypertension, and vascular disease in later life. The underlying mechanism is unclear. The foetal insulin hypothesis proposes that a single genetic predisposition to beta cell dysfunction/insulin resistance results in both reduced insulin-dependent foetal growth in utero, hence low birthweight, and predisposition to type 2 diabetes. The aim of this study was to test whether, as predicted by the foetal insulin hypothesis, there is an association between measures of paternal insulin resistance and offspring birthweight.

SUBJECTS AND METHODS

The Exeter Family Study of Childhood Health (EFSOCH) is a community-based study within central Exeter (UK), established to test the foetal insulin hypothesis prospectively. Associations were tested between offspring birthweight and paternal insulin resistance, calculated by homeostasis model assessment analysis in 986 families using data relating to singleton, non-diabetic, UK white pregnancies. Ethics approval was given by the North and East Devon local ethics committee.

RESULTS

Offspring birthweight was not significantly correlated with log paternal insulin resistance (r=0, p=0.91), log HDL cholesterol concentration (r=-0.02, p=0.47) or log triglyceride concentration (r=0, p=0.99) when corrected for paternal BMI and common confounders. Multiple linear regression analysis confirmed that paternal insulin resistance was not an independent predictor of offspring birthweight.

CONCLUSIONS/INTERPRETATION

Results from a young, adult, non-diabetic population do not support the foetal insulin hypothesis as an explanation for the association of low birthweight with insulin resistance.