(#4) Reappearance of C-peptide during the third trimester in type 1 diabetes pregnancy: pancreatic regeneration or fetal hyperinsulinism?

PRESENTED BY: Richard Oram

Authors
First NameLast NameAffiliation/Institution
RichardOramUniversity of Exeter
HelenMurphyUniversity of Cambridge
TimothyMcDonaldRoyal Devon and Exeter NHS Foundation Trust
AndrewHattersleyUniversity of Exeter
DeniceFeigUniversity of Toronto
ClaireMeekUniversity of Cambridge
   
 

Purpose

There is controversy about whether endogenous insulin secretion increases in late gestation in type 1 diabetes pregnancy. We aimed to assess longitudinal patterns of maternal C-peptide concentration and to investigate the mechanism for the changes seen during pregnancy.
 

Methods

C-peptide concentration was measured on serum samples at 12, 24 and 34 weeks from 127 participants in the continuous glucose monitoring in type 1 diabetes pregnancy trial (CONCEPTT). Maternal serum C-peptide and cord blood C-peptide were measured using a highly sensitive direct and solid-phase competitive electrochemiluminescence immunoassay respectively
 

Summary of Results

Three discrete patterns of maternal C-peptide trajectory were identified: Pattern 1 undetectable throughout pregnancy, n=74 (58%, maternal C-peptide <3 pmol/l); Pattern 2 detectable at baseline, n=22 (17%); Pattern 3 undetectable C-peptide at 12 and 24 weeks which became detectable at 34 weeks, n=31 (24%; maternal C-peptide 4-26 pmol/l at 34 weeks). The baseline characteristics and third trimester glucose profiles of women with pattern 1 and pattern 3 C-peptide trajectories were similar. The offspring of women with pattern 3 C-peptide trajectories had markedly increased rates of neonatal hypoglycemia (42% vs 14%; p=0.001), large-for-gestational-age (90% vs 60%; p=0.002) and neonatal intensive care admission (45% vs 23%; p=0.023), with elevated cord blood C-peptide (geometric mean 1319 vs 718 pmol/l; p=0.007) compared to offspring of women in pattern 1.
 

Conclusions

Increased C-peptide concentration at 34 weeks is associated with fetal hyperinsulinism, suggesting fetal to maternal transfer. We found no evidence for improved maternal beta cell function. First appearance of C peptide in late pregnancy could be used to identify pregnancies at highest risk of neonatal complications.