Objectives To explore and compare the relationships between postmenstrual age (PMA), insulin, C-peptide and blood glucose concentrations (BGC) in hyperglycaemic and euglycaemic preterm neonates (PMA <30 weeks).
Setting Dunedin Hospital Neonatal Intensive Care Unit, New Zealand.
Patients Preterm neonates were recruited and included nine insulin-treated hyperglycaemic and 20 euglycaemic neonates. Samples for euglycaemic neonates were obtained from leftover blood, and for insulin-treated neonates, additional blood was collected at the same time as the patients’ routine 4 hourly blood glucose test over a 24-hour period (six samples).
Main outcome measures Blood samples were collected, plasma was analysed for insulin and C-peptide and was measured in temporal association with BGC.
Results The euglycaemic neonates had a mean PMA (SD) of 28 (1.4) weeks and the insulin-treated neonates had 25.5 (1.8) weeks. C-peptide plasma concentrations were significantly lower (p<0.01) in the insulin-treated hyperglycaemic neonates (51.7 (100) pmol/L; 200(208) pmol/L) indicating lower insulin production. Insulin plasma concentrations (r=−0.38), BGC (r=−0.38), C-peptide plasma concentrations (r=0.36) and insulin/C-peptide ratios (r=−0.49) were all significantly affected by PMA (p<0.01). As expected, insulin plasma concentrations were higher in the insulin-treated hyperglycaemic neonates (156 (161) pmol/L; 93.2 (63.1) pmol/L, p<0.01) confirming that intravenous exogenous insulin reached these neonates.
Conclusions This study demonstrates that preterm neonates exhibit insulin resistance, hyperglycaemic neonates have lower insulin production than euglycaemic neonates and treatment with exogenous insulin did not appear to suppress insulin production in these neonates.
- insulin resistance
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Contributors ERS: substantial contribution to conception and design, acquisition of data, analysis and interpretation of data, drafted the initial manuscript and approved the final manuscript as submitted. DMR: substantial contribution to conception and design, supervised data collection, analysis and interpretation of data, reviewed and revised the manuscript and approved the final manuscript as submitted. BJW: substantial contribution to conception and design, supervised data collection, critically reviewed the manuscript and approved the final manuscript as submitted. RSB: substantial contribution to conception and design, supervised data collection, critically reviewed the manuscript and approved the final manuscript as submitted. NJM: substantial contribution to conception and design, analysis and interpretation of data, reviewed and revised the manuscript and approved the final manuscript as submitted.
Funding The School of Pharmacy, University of Otago for a PhD stipend for ERS. New Zealand Pharmacy Education and Research Foundation (NZPERF) for funding of the assay kits.
Competing interests None declared.
Patient consent Parental/guardian consent obtained.
Ethics approval Lower South Regional Ethics Committee, New Zealand.
Provenance and peer review Not commissioned; externally peer reviewed.
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