Differential Diagnosis for Heart Palpitations and Fluctuating Blood Sugar

• Single most likely diagnosis:
  • Anxiety or Stress-Related Palpitations: The patient's symptoms of heart palpitations at night, trouble falling asleep, and lightheadedness without any obvious cardiac triggers suggest a possible anxiety or stress-related component. The random onset of palpitations and the absence of other cardiac symptoms like chest pain or shortness of breath further support this diagnosis.
• Other Likely diagnoses:
  • Reactive Hypoglycemia: Given the patient's complaint of "fluctuating blood sugar" and feeling ill after consuming sugary or high-carb foods, reactive hypoglycemia is a possible diagnosis. This condition is characterized by symptoms that occur after eating, due to an excessive insulin response, leading to low blood sugar.
  • Hyperthyroidism: Although not directly related to the complaint of fluctuating blood sugar, hyperthyroidism can cause heart palpitations, anxiety, and an increased heart rate, which might be exacerbated at night. The absence of other symptoms like weight loss or exophthalmos does not rule out this diagnosis entirely.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
  • Cardiac Arrhythmias (e.g., Atrial Fibrillation, Supraventricular Tachycardia): Although the patient denies chest pain or shortness of breath, cardiac arrhythmias can sometimes present with palpitations and lightheadedness alone. These conditions require prompt diagnosis and treatment to prevent complications like stroke or heart failure.
  • Pheochromocytoma: A rare tumor of the adrenal gland that can cause episodic palpitations, hypertension, and sweating. Although the patient denies diaphoresis, this diagnosis is critical not to miss due to its potential for severe hypertension and cardiac complications.
• Rare diagnoses:
  • Insulinoma: A rare tumor of the pancreas that produces excess insulin, leading to episodes of hypoglycemia. The patient's complaint of feeling ill after sugary foods could be a manifestation of hypoglycemia, but this diagnosis is less likely without more specific symptoms like confusion or loss of consciousness during episodes.
  • Postural Orthostatic Tachycardia Syndrome (POTS): Characterized by a rapid increase in heart rate upon standing, POTS could potentially cause palpitations and lightheadedness. However, the patient's symptoms primarily occur at night while lying down, making this diagnosis less likely.