What is a common symptom of hypoglycemia in a newborn?

Cyanosis is indeed a common symptom of hypoglycemia in a newborn. When a newborn experiences low blood sugar levels, the body may not receive enough glucose to meet its energy demands, leading to inadequate oxygen delivery to tissues. This can manifest as a bluish discoloration of the skin, especially around the lips and extremities, indicating a potential oxygen deficit in the newborn. Cyanosis serves as a critical sign that necessitates further assessment and intervention to address the underlying hypoglycemia and ensure the newborn's safety and health.

In contrast, high muscle tone is generally not associated with hypoglycemia; rather, low muscle tone is often observed due to the metabolic imbalance. Normal feeding would suggest that the newborn is stable and not experiencing hypoglycemia, and a rash does not correlate directly with low blood sugar levels. Thus, cyanosis stands out as a significant and observable symptom in the context of hypoglycemia in newborns.