Reappearance of C-Peptide During the Third Trimester of Pregnancy in Type 1 Diabetes: Pancreatic Regeneration or Fetal Hyperinsulinism?

Pregnancy induces longitudinal changes in urinary C-peptide creatinine ratio in women with type 1 diabetes

AIMS

Changes in maternal serum C-peptide have been described during pregnancy in women with Type 1 diabetes. We aimed to determine whether in these women, C-peptide, as measured by the urinary C-peptide creatinine ratio (UCPCR), display changes during the course of pregnancy and in the postpartum period.

METHODS

In this longitudinal study including 26 women, UCPCR was measured in the first, second, and third trimester of pregnancy, and postpartum, using a high sensitivity two-step chemiluminescent microparticle immunoassay.

RESULTS

UCPCR was detectable in 7/26 (26.9%) participants in the first trimester, 10/26 (38.4%) in the second trimester, and 18/26 (69.2%) in the third trimester. Changes in UCPCR concentrations were observed throughout pregnancy, significantly increasing from first to third trimester. UCPCR concentration in the three trimesters was associated with a shorter duration of diabetes and in the third trimester also with first trimester UCPCR.

CONCLUSION

UCPCR detects longitudinal changes during pregnancy in women with type 1 diabetes mellitus, more marked in those with shorter diabetes duration.

Prenatal air pollution, fetal β-cell dysfunction and neurodevelopmental delay

BACKGROUND

Emerging evidence has reported significant associations of prenatal air pollution exposure with neurodevelopmental delay in offspring. Sensitive exposure windows and the modifiable factor remain elusive.

OBJECTIVE

We aim to identify sensitive windows of air pollution during pregnancy on neurodevelopmental delay, and examine whether cord blood C-peptide mediates the relationship.

METHODS

This study included 7438 mother-newborn pairs in Hefei, China, from 2015 to 2021. Weekly exposure to particulate matter of aerodynamic diameter <2.5 µm, 10 µm (PM2.5, PM10), nitrogen dioxide (NO2) and carbon monoxide (CO) was estimated at regulatory air monitoring stations in Hefei. Denver Developmental Screening Test-II and the Gesell Developmental Schedules were applied to assess the neurodevelopmental delay in children 6-36 mon of age. Distributed lag nonlinear models examined sensitive time windows of prenatal air pollutants exposure. Mediation analysis estimated the mediating role of cord blood C-peptide.

RESULTS

The sensitive PM2.5, PM10, NO2, and CO exposure windows associated with neurodevelopmental delay were throughout pregnancy. Weekly air pollutants exposure was related to higher neurodevelopmental delay risks [cumulative odds ratio (OR): 1.40(1.29,1.53) in PM2.5 (per 10 μg/m3), 1.40(1.28,1.53) in PM10 (per 10 μg/m3), 1.41(1.30,1.52) in CO (per 0.1 mg/m3), and 1.49(1.29,1.72) in NO2 (per 5 μg/m3)]. Mediation analysis indicated 18.3 % contributions of cord C-peptide to the relationship [average mediation effect: 0.04(0.01.0.06); average direct effect: 0.15(0.07.0.25)].

CONCLUSIONS

Exposure to air pollution throughout pregnancy is linked to neurodevelopmental delay mediated by poorer fetal β-cell function. Screening and treatment of abnormal glucose metabolism in infants could benefit the prevention of air pollution-associated neurodevelopment delay.

Antenatal depression moderated the association between gestational diabetes mellitus and fetal hyperinsulinism

BACKGROUND

Gestational diabetes mellitus and antenatal depression are common comorbidities. However, the combined effects of antenatal depression and diabetes mellitus during pregnancy on fetal β-cell function are unknown.

OBJECTIVE

This study aimed to test whether the association of maternal gestational diabetes mellitus and glucose metabolism with cord blood C-peptide levels varies with antenatal depression.

STUDY DESIGN

Data on mother-child pairs (N=5734) from the Maternal and Infant Health Cohort Study in Hefei were analyzed. Gestational diabetes mellitus was diagnosed using the 75-g oral glucose tolerance test at 24 to 28 weeks of gestation. Antenatal depression was measured using the Edinburgh Postnatal Depression Scale during midpregnancy and late pregnancy. Cord blood samples were collected at delivery and tested for C-peptide levels.

RESULTS

A total of 1054 mothers (18.38%) were diagnosed with gestational diabetes mellitus. Gestational diabetes mellitus was associated with a 5.57 (95% confidence interval, 3.65-7.50) percentile higher cord blood C-peptide level. This association varied with depression severity: the differences in cord blood C-peptide percentile for gestational diabetes mellitus vs no gestational diabetes mellitus were 5.12 (95% confidence interval, 2.81-9.75) for nonantenatal depression, 7.36 (95% confidence interval, 2.85-13.38) for moderate antenatal depression, and 10.06 (95% confidence interval, 4.69-14.8) for severe antenatal depression in midpregnancy. Similar associations stratified by antenatal depression in late pregnancy were observed. Antenatal depression was significantly positively correlated with fetal hyperinsulinism in participants with gestational diabetes mellitus but not in participants without gestational diabetes mellitus.

CONCLUSION

Antenatal depression, which is related to maternal hyperglycemia, can aggravate the risk of fetal hyperinsulinism in early life.

An unwelcome inheritance: childhood obesity after diabetes in pregnancy

Diabetes in pregnancy affects 20 million women per year and is associated with increased risk of obesity in offspring, leading to insulin resistance and cardiometabolic disease. Despite the substantial public health ramifications, relatively little is known about the pathophysiological mechanisms underlying obesity in these high-risk children, which creates a barrier to successful intervention. While maternal glucose itself is undeniably a major stimulus upon intrauterine growth, the degree of offspring hyperinsulinism and disturbed lipid metabolism in mothers and offspring are also likely to be implicated in the disease process. The aim of this review is to summarise current understanding of the pathophysiology of childhood obesity after intrauterine exposure to maternal hyperglycaemia and to highlight possible opportunities for intervention. I present here a new unified hypothesis for the pathophysiology of childhood obesity in infants born to mothers with diabetes, which involves self-perpetuating twin cycles of pancreatic beta cell hyperfunction and altered lipid metabolism, both acutely and chronically upregulated by intrauterine exposure to maternal hyperglycaemia.

Maternal 25(OH)D attenuates the relationship between ambient air pollution during pregnancy and fetal hyperinsulinism

Inflammatory responses have been demonstrated to link air pollution with insulin resistance and type 2 diabetes in adults. However, few studies have focused on the relationship between prenatal air pollution and fetal β-cell function and the mediating effect of systematic inflammation remains elusive. Whether the anti-inflammatory effect of vitamin D could attenuate the β-cell dysfunction in early life warrants further investigations. We aimed to determine whether maternal blood 25(OH)D attenuates the associations of ambient air pollution during pregnancy with fetal hyperinsulinism mediated by maternal inflammatory response. A total of 8250 mother-newborn pairs were included between 2015 and 2021 in the Maternal & Infants Health in Hefei study. Weekly mean air pollution exposure to fine particles (PM_2.5 and PM₁₀), SO₂, and CO was estimated across pregnancy. Maternal serum samples in the third trimester were used to measure the high-sensitivity c-reactive protein (hs-CRP) and 25(OH)D. Cord blood samples at delivery were collected for the measurement of C-peptide. Fetal hyperinsulinism was based on cord C-peptide >90th centile. An increased fetal hyperinsulinism risk was associated with per 10 μg/m³ increase in PM_2.5 [odds ratios (OR): 1.45 (95% confidence interval (CI):1.32, 1.59)], per 10 μg/m³ increase in PM₁₀ [OR = 1.49 (95% CI:1.37, 1.63)], per 5 μg/m³ increase in SO₂ [OR = 1.91 (95% CI: 1.70, 2.15)], and per 0.1 mg/m³ increase in CO [OR = 1.48 (95% CI:1.37, 1.61)] across pregnancy. Mediation analysis showed a 16.3% contribution of maternal hsCRP to the relationship between air pollution throughout pregnancy and fetal hyperinsulinism. Air pollution-associated higher levels of hsCRP and risk of fetal hyperinsulinism could be attenuated by higher maternal 25(OH)D levels. Prenatal ambient air pollution exposures were associated with an increased fetal hyperinsulinism risk mediated by maternal serum hsCRP. Higher antenatal 25(OH)D levels could attenuate air pollution-induced inflammatory responses and hyperinsulinism risk.

Pregnancy induces pancreatic insulin secretion in women with long-standing type 1 diabetes

INTRODUCTION

Pregnancy entails both pancreatic adaptations with increasing β-cell mass and immunological alterations in healthy women. In this study, we have examined the effects of pregnancy on β-cell function and immunological processes in long-standing type 1 diabetes (L-T1D).

RESEARCH DESIGN AND METHODS

Fasting and stimulated C-peptide were measured after an oral glucose tolerance test in pregnant women with L-T1D (n=17) during the first trimester, third trimester, and 5-8 weeks post partum. Two 92-plex Olink panels were used to measure proteins in plasma. Non-pregnant women with L-T1D (n=30) were included for comparison.

RESULTS

Fasting C-peptide was detected to a higher degree in women with L-T1D during gestation and after parturition (first trimester: 64.7%, third trimester: 76.5%, and post partum: 64.7% vs 26.7% in non-pregnant women). Also, total insulin secretion and peak C-peptide increased during pregnancy. The plasma protein levels in pregnant women with L-T1D was dynamic, but few analytes were functionally related. Specifically, peripheral levels of prolactin (PRL), prokineticin (PROK)-1, and glucagon (GCG) were elevated during gestation whereas levels of proteins related to leukocyte migration (CCL11), T cell activation (CD28), and antigen presentation (such as CD83) were reduced.

CONCLUSIONS

In summary, we have found that some C-peptide secretion, that is, an indirect measurement of endogenous insulin production, is regained in women with L-T1D during pregnancy, which might be attributed to elevated peripheral levels of PRL, PROK-1, or GCG.

C-peptide determination in the diagnosis of type of diabetes and its management: A clinical perspective

Impaired beta-cell function is a recognized cornerstone of diabetes pathophysiology. Estimates of insulin secretory capacity are useful to inform clinical practice, helping to classify types of diabetes, complication risk stratification and to guide treatment decisions. Because C-peptide secretion mirrors beta-cell function, it has emerged as a valuable clinical biomarker, mainly in autoimmune diabetes and especially in adult-onset diabetes. Nonetheless, the lack of robust evidence about the clinical utility of C-peptide measurement in type 2 diabetes, where insulin resistance is a major confounder, limits its use in such cases. Furthermore, problems remain in the standardization of the assay for C-peptide, raising concerns about comparability of measurements between different laboratories. To approach the heterogeneity and complexity of diabetes, reliable, simple and inexpensive clinical markers are required that can inform clinicians about probable pathophysiology and disease progression, and so enable personalization of management and therapy. This review summarizes the current evidence base about the potential value of C-peptide in the management of the two most prevalent forms of diabetes (type 2 diabetes and autoimmune diabetes) to address how its measurement may assist daily clinical practice and to highlight current limitations and areas of uncertainties to be covered by future research.

N-3 PUFA and Pregnancy Preserve C-Peptide in Women with Type 1 Diabetes Mellitus

Type 1 diabetes (T1DM) is an autoimmune disease characterized by the gradual loss of β-cell function and insulin secretion. In pregnant women with T1DM, endogenous insulin production is absent or minimal, and exogenous insulin is required to control glycemia and prevent ketoacidosis. During pregnancy, there is a partial decrease in the activity of the immune system, and there is a suppression of autoimmune diseases. These changes in pregnant women with T1DM are reflected by Langerhans islet enlargement and improved function compared to pre-pregnancy conditions. N-3 polyunsaturated fatty acids (n-3 PUFA) have a protective effect, affect β-cell preservation, and increase endogenous insulin production. Increased endogenous insulin production results in reduced daily insulin doses, better metabolic control, and adverse effects of insulin therapy, primarily hypoglycemia. Hypoglycemia affects most pregnant women with T1DM and is several times more common than that outside of pregnancy. Strict glycemic control improves the outcome of pregnancy but increases the risk of hypoglycemia and causes maternal complications, including coma and convulsions. The suppression of the immune system during pregnancy increases the concentration of C-peptide in women with T1DM, and n-3 PUFA supplements serve as the additional support for a rise in C-peptide levels through its anti-inflammatory action.