Clinical presentation

• Hyperglycaemia is usually picked up incidentally on routine blood glucose assessment or in response to finding glycosuria.

• It may be noted as part of the workup of a sick baby.

Definition of hyperglycaemia

The upper end of the ‘normal’ range for blood sugar has not been clearly defined in neonatal practice, although levels of >7 mmol/L are unusual in healthy term babies. Most neonatologists would treat by reducing sugar intake or with insulin if the blood sugar is >10–12 mmol/L, especially if there is significant glycosuria causing an osmotic diuresis, particularly in sick preterm babies. However, tighter glucose control in intensive care patients may be more appropriate.

Approach to the problem

Hyperglycaemia usually occurs in very preterm or small-for-gestational age (SGA) babies due to impaired insulin secretion and/or insulin resistance as well as immaturity of the liver enzymes involved in glucose metabolism (dysregulation of glucose homeostasis).

If hyperglycaemia occurs out of context (such as a previously healthy appropriate-for-gestational-age, enterally fed infant), the cause needs to be identified.

Differential diagnosis

Commonly

• Iatrogenic from excessive intravenous glucose delivery

• Impaired glucose homeostasis in preterm/SGA baby

• Sepsis

• Stress

• Drugs particularly corticosteroids

Rarely

• Transient neonatal diabetes

• Permanent neonatal diabetes

• Pancreatic agenesis

Investigations

• Measure the true blood glucose to confirm the diagnosis.

• Calculate the glucose infusion rate (see Appendix 1) to exclude excessive glucose delivery.