title: Pregnancy-induced rise in serum C-peptide concentrations in women with type 1 diabetes.
abstract: OBJECTIVE
  The purpose of this study was to investigate whether pregnancy induces increased insulin production as a marker of improved beta-cell function in women with long-term type 1 diabetes.
  
  
  METHODS
  This was a prospective study of 90 consecutive pregnant women with type 1 diabetes. At 8, 14, 21, 27, and 33 weeks blood samples were drawn for measurements of A1C, C-peptide, and serum glucose. C-peptide (detection limit: 6 pmol/l) was considered stimulated at a corresponding serum glucose concentration >or=5.0 mmol/l. GAD antibody concentration was determined at 8 and 33 weeks in 35 women.
  
  
  RESULTS
  C-peptide concentrations gradually increased throughout pregnancy regardless of serum glucose concentrations in the 90 women with a median duration of diabetes of 17 years (range 1-36 years). Among 35 women with paired recordings of stimulated C-peptide, C-peptide production was detectable in 15 (43%) at 8 weeks and in 34 (97%) at 33 weeks (P < 0.0001), and median C-peptide gradually increased from 6 to 11 pmol/l (P = 0.0004) with a median change of 50% (range -50 to 3,271%) during pregnancy. GAD antibodies were present in 77% with no change from 8 to 33 weeks (P = 0.85). Multivariate regression analysis revealed a positive association between the absolute increase in C-peptide concentrations during pregnancy and decreased A1C from 8 to 33 weeks (P = 0.003).
  
  
  CONCLUSIONS
  A pregnancy-induced increase in C-peptide concentrations in women with long-term type 1 diabetes was demonstrated, even in women with undetectable C-peptide concentrations in early pregnancy. This increase is suggestive of improved beta-cell function and was associated with improvement in glycemic control during pregnancy.
authors.affiliation: Center for Pregnant Women with Diabetes, Rigshospitalet, Faculty of Health Sciences, Copenhagen, Denmark. enel@dadlnet.dk
authors.forename: Lene Ringholm
authors.initials: LR
authors.lastname: Nielsen
authors.forename: Jens F
authors.initials: JF
authors.lastname: Rehfeld
authors.forename: Ulrik
authors.initials: U
authors.lastname: Pedersen-Bjergaard
authors.forename: Peter
authors.initials: P
authors.lastname: Damm
authors.forename: Elisabeth R
authors.initials: ER
authors.lastname: Mathiesen
mesh_terms: D000328:Adult; D017668:Age of Onset; D001786:Blood Glucose / Q000378:metabolism; D002096:C-Peptide / Q000097:blood*; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000150:complications* / Q000188:drug therapy; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000378:metabolism / Q000627:therapeutic use; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000378:metabolism; D049590:Postpartum Period / Q000378:metabolism; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood* / Q000188:drug therapy; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third; D011446:Prospective Studies; D015430:Weight Gain
chemical_list: D001786:Blood Glucose; D002096:C-Peptide; D006442:Glycated Hemoglobin; D007328:Insulin