The effect of insulin administration on c-peptide in critically ill patients with type 2 diabetes

Marco Crisman, Luca Lucchetta, Nora Luethi, Luca Cioccari, Que Lam, Glenn M. Eastwood, Rinaldo Bellomo, Johan Mårtensson

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Background: In critically ill patients with permissive hyperglycemia, it is uncertain whether exogenous insulin administration suppresses or enhances c-peptide secretion (a marker of pancreatic beta-cell response). We aimed to explore this effect in patients with type 2 diabetes. Methods: We prospectively enrolled a cohort of 45 critically ill patients with type 2 diabetes managed according to a liberal glucose protocol (target blood glucose 10–14 mmol/l). We recorded the administration of insulin and oral hypoglycemic agents and measured plasma c-peptide as surrogate marker of endogenous insulin secretion on the first two consecutive days in ICU. Results: Overall, 20 (44.4%) patients required insulin to achieve target blood glucose. Insulin-treated patients had higher glycated hemoglobin A1c, more premorbid insulin-requiring type 2 diabetes, and greater blood glucose levels but lower c-peptide levels on admission. Premorbid insulin-requiring diabetes was independently associated with lower admission c-peptide, whereas greater plasma creatinine was independently associated with higher levels. Increases in c-peptide were positively correlated with an increase in blood glucose both in patients who did (r = 0.54, P = 0.01) and did not (r = 0.56, P = 0.004) receive insulin. However, insulin administration was independently associated with a greater increase in c-peptide (P = 0.04). This association was not modified by the use of oral insulin secretagogues. Conclusions: C-peptide, a marker of beta-cell response, responds to and is influenced by glycemia and renal function in critically ill patients with type 2 diabetes. In addition, in our cohort, exogenous insulin administration was associated with a greater increase in c-peptide in response to hyperglycemia. Trial Registration Australian New Zealand Clinical Trials Registry (ACTRN12615000216516).

Original languageEnglish
Article number50
JournalAnnals of Intensive Care
Issue number1
Publication statusPublished - 1 Dec 2017


  • Blood glucose
  • C-peptide
  • Critical care, beta-cell
  • Diabetes mellitus
  • Insulin

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