Long-duration type 1 diabetes: persistent C-peptide levels tied to reduced hypoglycaemia but not HbA1c

  • Marren SM & al.
  • Diabet Med
  • 6 Apr 2019

  • curated by Sarfaroj Khan
  • UK Clinical Digest
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  • In adults with long-duration type 1 diabetes (T1D), persistent C-peptide level (>200 pmol/L) is associated with reduced self-reported hypoglycaemia and insulin doses but not with glycated haemoglobin (HbA1c) level.

Why this matters

  • Findings suggest that individuals with persistent C-peptide receiving routine care are potentially under-treated and routinely testing C-peptide and subsequently setting personalised targets for treatment intensification may improve glycaemic control and complication rates.

Study design

  • This cross-sectional case-control study determined ongoing endogenous insulin secretion of 221 patients with T1D by measuring C-peptide levels after mixed-meal tolerance test.
  • Self-reported hypoglycaemia, HbA1c (visit and historic), insulin dose and microvascular complications were compared in patients with preserved (n=70) and low C-peptide (n=151) levels.
  • Funding: Juvenille Diabetes Research Foundation.

Key results

  • Median C-peptide level was 114 (interquartile range [IQR], 43-273) pmol/L and
  • Preserved vs low C-peptide group had lower symptomatic (5.9 vs 7.5 episodes/month; incidence rate ratio [IRR], 0.79; P=.001) and asymptomatic episodes of hypoglycaemia per month (1.0 vs 2.9 episodes/month; IRR, 0.35; P<.001>
  • Visit HbA1c level was marginally higher in the preserved vs low C-peptide group (69 vs 67 mmol/mol; P=.06), but no significant difference was observed in historic HbA1c level between 2 groups (P=.4).
  • Compared with low C-peptide group, preserved C-peptide group had lower daily insulin doses (0.68 vs 0.81 units/kg; P=.01).


  • Self-reported hypoglycaemia.

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