ORIGINAL ARTICLE

An inadequate glycaemic response to glucagon is linked to insulin resistance in preterm infants?

L Jackson, A Burchell, A McGeechan and R Hume

Departments of Obstetrics and Gynaecology and Child Health, Tayside Institute of Child Health, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, Scotland, UK

Correspondence to:
Correspondence to:
Professor R Hume, Tayside Institute of Child Health, University of Dundee, Ninewells Hospital & Medical School, Dundee DD1 9SY, UK;
r.hume{at}dundee.ac.uk

Aims: To define clinical, metabolic, and hormonal characteristics of preterm infants relative to glucagon responsiveness.

Methods: Two phase study of 78 preterm infants (25–36 weeks gestation) on regular four hourly feeds anticipating discharge home at 36 weeks mean corrected gestation. In phase 1 infants were fasted until hypoglycaemic, or maximally for eight hours. Endocrine and metabolic profiles were obtained at completion. Phase 2 was performed the following day. A feed was omitted and replaced by a bolus dose of intravenous glucagon (100 µg/kg). Main outcome measures were measurements of blood glucose and lactate concentrations, taken immediately pre-glucagon, and thereafter every 15 minutes for 60 minutes. A rise in glucose concentration of >1 mmol/l (55 infants) was defined as an adequate response to glucagon. An inadequate glycaemic response was <1 mmol/l (23 infants).

Results: Several differences in fasting blood glucose and hormone concentrations were identified in infants with an inadequate glycaemic response to glucagon compared to those with an adequate response: relative fasting hyperglycaemia (mean 3.7 v 3.3 mmol/l, p = 0.008); fasting hyperinsulinaemia (mean 4.3 v 2.6 mU/l, p = 0.014); an increased insulin:glucagon ratio (0.19 v 0.11, p = 0.014), and a lower insulin sensitivity QUICKI index (0.19 v 0.22, p = 0.04). There was no distinctive phenotype to reliably predict response to glucagon.

Conclusion: Some preterm infants show an inadequate glycaemic response to glucagon and have features suggestive of insulin resistance. The potential long term implications of such insulin resistance may have appreciable public health consequences.

Keywords: preterm; glucose; insulin; glucagon; insulin resistance

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