The association between a single abnormal glucose and fetal c-peptide

AIM

We aimed to evaluated if fetuses of subjects with one elevated value on the 3-h GTT had a measurable physiologic difference in fetal C-peptide levels as compared to those with no elevated values on the GTT.

METHODS

We performed a prospective cohort study to evaluate insulin levels in singleton non-anomalous fetuses of subjects with one elevated value on the GTT as compared to subjects with no elevated values on their GTT. Fetal insulin levels were measured by fetal C-peptide in cord blood. Distribution of data was assessed and outliers representing values > the 99th and < the 1st percentiles were excluded. Data were log transformed to achieve normal distribution and univariable analyses were performed to compare fetal C-peptide levels, baseline maternal characteristics and perinatal outcomes in subjects with one elevated value as compared those with no elevated values.

RESULTS

Our analysis included 99 subjects, with 49 subjects in the one elevated value group and 50 subjects in the no elevated values group. Fetal C-peptide levels (picomoles per liters, pmol/L), were significantly higher in the elevated value group as compared to the no elevated value group (mean ± SD; 4.6 ± 0.8 vs. 4.3 ± 0.7, P = 0.046, respectively). In univariable analysis, there was no significant difference in maternal characteristics or adverse composite perinatal outcomes.

CONCLUSION

Fetuses of subjects who had one elevated value on their GTT had a measurable physiologic difference in C-peptide levels as compared to fetuses of subjects with no elevated values on the GTT.

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.