Plasma C-peptide concentration in women with Type 1 diabetes during early and late pregnancy

Authors

  • H. R. Murphy,

    1. University of Cambridge Metabolic Research Laboratories and NIHR Cambridge Biomedical Research Centre, Institute of Metabolic Science, Addenbrooke’s Hospital
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  • D. Elleri,

    1. University of Cambridge Metabolic Research Laboratories and NIHR Cambridge Biomedical Research Centre, Institute of Metabolic Science, Addenbrooke’s Hospital
    2. Department of Paediatrics, University of Cambridge
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  • J. M. Allen,

    1. University of Cambridge Metabolic Research Laboratories and NIHR Cambridge Biomedical Research Centre, Institute of Metabolic Science, Addenbrooke’s Hospital
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  • D. Simmons,

    1. Cambridge University Hospitals NHS Foundation Trust, Institute of Metabolic Science, Cambridge, UK
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  • M. Nodale,

    1. University of Cambridge Metabolic Research Laboratories and NIHR Cambridge Biomedical Research Centre, Institute of Metabolic Science, Addenbrooke’s Hospital
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  • R. Hovorka

    1. University of Cambridge Metabolic Research Laboratories and NIHR Cambridge Biomedical Research Centre, Institute of Metabolic Science, Addenbrooke’s Hospital
    2. Department of Paediatrics, University of Cambridge
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  • (Clinical Trials Registry No; ISR CTN 62568875)

Helen R Murphy. E-mail: hm386@medschl.cam.ac.uk

Abstract

Diabet. Med. 29, e361–e364 (2012)

Abstract

Aims  There are previous suggestions of increased C-peptide concentration in women with Type 1 diabetes during pregnancy. Our aim was to re-evaluate the hypothesis of a pregnancy-induced increase by measuring plasma C-peptide concentration in women with stable blood glucose control under standardized fasting and meal-stimulated conditions.

Methods  Ten women with Type 1 diabetes; median age 31.1 years, median diabetes duration 19 years, median HbA1c 52 mmol/mol (6.9%) were admitted to a clinical research facility for two 24-h visits in early (12–16 weeks) and late (28–32 weeks) pregnancy. Women They ate standardized study meals - 80-g carbohydrate dinner, 60-g carbohydrate breakfast, and fasted between meals and overnight. Closed-loop insulin delivery maintained stable and comparable glycaemic conditions. Paired samples for plasma glucose and C-peptide were obtained.

Results  Plasma glucose levels were comparable in early (median 6.5 mmol/l; interquartile range 5.6–8.6) and late pregnancy (median 7.0 mmol/l; interquartile range 6.1–7.8; P = 0.72). There was no change in fasting or meal-stimulated plasma C-peptide concentration from early to late pregnancy; mean difference 4.0 pmol/l (95% CI −6.0 to 7.0; P = 0.9). Four women had detectable C-peptide; peak (range) early vs. late pregnancy 48.5 (10–115) vs. 40.0 pmol/l (80–105); P = 0.5, which was weakly associated with plasma glucose; R2 = 0.15, P < 0.0001.

Conclusions  We found no gestational changes in plasma C-peptide concentration. Previously reported increases may reflect differences in glucose control and/or exogenous insulin doses. This study highlights the importance and challenges of standardizing experimental conditions for accurate plasma C-peptide measurement during Type 1 diabetes pregnancy.

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