The definition of neonatal hypoglycaemia is capillary plasma glucose <2.6 mmol/L.
The threshold for invasive treatment (nasogastric feeds or IV Dextrose) is glucose <2.0 mmol/L on two consecutive readings despite maximal support for feeding, or if the baby is not feeding effectively.
Any baby with clinical signs of hypoglycaemia, should be treated with IV Dextrose as soon as possible.
Reference: National Institute for Health and Clinical Excellence (2015). Diabetes in pregnancy: Management of diabetes and its complications from preconception to the postnatal period. Version 2.1. Nice Guideline (NG) 3. London: NICE.