Symptoms & Emergency Warning Signs

When your child has a condition that causes hypoinsulinemic hypoglycemia (low blood sugar without ketones), the most important tool you have is the ability to recognize symptoms early. Because infants and toddlers cannot tell you they “feel low,” you must rely on subtle changes in their behavior and physical appearance.

Recognizing Low Blood Sugar (Hypoglycemia)

In infants, hypoglycemia is often “silent” or presents with very general symptoms that could easily be mistaken for hunger or tiredness ^[1]. Research shows that even experienced doctors cannot always tell a child is low just by looking at them; regular glucose monitoring is essential ^[2].

Common early signs in infants and toddlers include:

• Jitteriness or Tremors: Shaking or “jumpy” movements in the arms or legs ^[3].
• Poor Feeding: A sudden lack of interest in the bottle or breast, or a weak suck ^[1].
• Irritability: Unusual or inconsolable crying.
• Lethargy: Being exceptionally sleepy, difficult to wake up, or “floppy” (low muscle tone) ^[3].
• Temperature Instability: Feeling unusually cold to the touch.

Identifying Hemihypertrophy (Overgrowth)

Hemihypertrophy (also called lateralized overgrowth) means that one side or part of the body is larger than the other ^[4]. This happens because the insulin signaling pathway causes cells to grow faster in certain areas ^[5].

What parents should look for:

• Limb Asymmetry: One leg may be longer or thicker than the other. You may notice one shoe fits tighter than the other or one pant leg appears shorter ^[6].
• Facial Asymmetry: One cheek or one side of the tongue (macroglossia) may appear larger. This can sometimes lead to difficulty swallowing or noisy breathing ^[7][8].
• Trunk Asymmetry: One side of the abdomen or chest may seem more prominent than the other ^[9].

Red Flags: When to Call 911 Immediately

Severe, prolonged low blood sugar can lead to hypoglycemic brain injury, which may cause long-term challenges like developmental delays or seizures ^[10][11].

Seek emergency medical care immediately if your child experiences:

• Seizures: Jerking movements, staring spells, or eyes rolling back ^[11].
• Apnea: Pauses in breathing or blue-tinted skin/lips ^[10].
• Unresponsiveness: You cannot wake the child or they do not react to your voice or touch.
• Vomiting with Low Blood Sugar: If your child cannot keep down sugar-containing fluids or food, they need an IV immediately ^[12].

The Emergency Protocol

Every family must have a written “Low Sugar Action Plan” completed by their clinician. In general, the protocol follows these steps:

1. Check: If you suspect a low, check the blood sugar immediately.
2. Treat (If Conscious): If the child is awake and can swallow safely, give a fast-acting sugar as directed by your doctor ^[13].
3. Rescue (If Unconscious or Seizing): Do NOT put food or liquid in their mouth. Administer Glucagon if it has been prescribed for you ^[14]. Do not delay rescue treatment or glucagon to wait for a fingerstick if the child is symptomatic.
4. Call: Call 911 or your local emergency number immediately while rescue treatment is being given.

Sick Day Rules

Minor illnesses like a common cold or a stomach bug are much more dangerous for a child with this condition. Fever and infection increase the body’s demand for sugar, while vomiting makes it impossible to provide that sugar orally ^[12].

• Never Fast: Even if they aren’t hungry, they must continue to receive sugar. Use small, frequent sips of clinician-prescribed sugar-containing liquids ^[15].
• Increase Monitoring: Check blood sugar more frequently (e.g., every 1–2 hours) during an illness, as directed by your plan ^[16].
• Low Threshold for ER: If your child is unable to retain their prescribed feed or has repeated low readings, contact the emergency team or go to the emergency room for IV Dextrose (sugar water) ^[17]. Explain to the ER staff that your child has a “metabolic emergency” and cannot tolerate fasting ^[12].