Differential Diagnosis for Low Blood Glucose with Elevated C-Peptide
Single Most Likely Diagnosis
- Insulinoma: This is a tumor of the pancreas that produces excess insulin, leading to episodes of low blood glucose. The elevated C-peptide level confirms that the insulin is endogenously produced, making insulinoma the most likely diagnosis.
Other Likely Diagnoses
- Factitious Hypoglycemia: This condition occurs when someone intentionally takes insulin or oral hypoglycemic medications, leading to low blood glucose. Elevated C-peptide levels can be seen if the individual is taking oral hypoglycemic agents that stimulate insulin release.
- Reactive Hypoglycemia: Also known as postprandial hypoglycemia, this condition can occur after eating, especially if the meal is high in simple carbohydrates. It is less likely to cause severely low blood glucose but can be a consideration.
- Glycogen Storage Diseases: Certain types of glycogen storage diseases can lead to hypoglycemia due to impaired glycogen breakdown. Elevated C-peptide levels would be expected as these conditions do not directly affect insulin production.
Do Not Miss Diagnoses
- Pituitary or Other Hormonal Imbalances: Certain hormonal deficiencies or excesses (e.g., adrenal insufficiency, growth hormone deficiency) can lead to hypoglycemia. These conditions are critical to identify due to their potential for severe morbidity and mortality if left untreated.
- Critical Illness: Severe illnesses, such as sepsis or liver failure, can cause hypoglycemia. The mechanism may involve impaired glucose production or increased glucose utilization, and C-peptide levels can be elevated due to stress-induced insulin resistance.
Rare Diagnoses
- Beckwith-Wiedemann Syndrome: A rare genetic disorder that can cause hypoglycemia due to pancreatic cell hyperplasia leading to excessive insulin production.
- Pancreatic Nesidioblastosis: A rare condition characterized by an abnormal overgrowth of pancreatic islet cells, leading to excessive insulin production and hypoglycemia.
- Autoimmune Hypoglycemia: A rare condition where autoantibodies against insulin or its receptor cause hypoglycemia. This can be associated with elevated C-peptide levels due to the body's attempt to counteract the hypoglycemic effect.