Differential Diagnosis

• Single most likely diagnosis
  • G) Type 1 diabetes mellitus: The patient's presentation with hyperglycemia (glucose concentration of 750 mg/dL), decreased serum C-peptide concentration, and diabetic ketoacidosis (indicated by shallow and labored breathing, and likely metabolic acidosis given the context) is highly suggestive of Type 1 diabetes mellitus, especially in a pediatric patient. The presence of anti-insulin antibodies further supports this diagnosis.
• Other Likely diagnoses
  • D) Iatrogenic hyperinsulinemia: Although less likely given the context, iatrogenic hyperinsulinemia could present with hypoglycemia, but the hyperglycemic state described doesn't align well with this condition. However, it's considered due to the mention of "anti-insulin bodies," which might be a confusion or misprint but could imply an insulin-related issue.
  • H) Type 2 diabetes mellitus: Though less common in pediatric patients presenting with such severe symptoms, Type 2 diabetes mellitus is a consideration, especially with the rising incidence in younger populations. However, the presence of anti-insulin antibodies and the severity of presentation lean more towards Type 1.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • F) Insulinoma: A rare tumor that produces excess insulin, leading to hypoglycemia, not hyperglycemia. However, in the differential for any severe glucose imbalance, especially with "anti-insulin bodies" mentioned, it's crucial to consider, despite the patient's hyperglycemic state.
  • B) Diabetes insipidus: This condition involves an inability to regulate fluids in the body due to problems with the antidiuretic hormone (ADH). While it can lead to severe dehydration and electrolyte imbalances, the primary presentation is polyuria and polydipsia, not directly aligned with the symptoms described.
• Rare diagnoses
  • A) Autoimmune hypothyroidism: While hypothyroidism can affect glucose metabolism, it is not directly linked to the acute presentation of diabetic ketoacidosis or the specific laboratory findings mentioned.
  • C) Hyperparathyroidism: This condition affects calcium levels and bone health, not directly related to the acute glucose and electrolyte imbalance described.
  • E) Insulin resistance syndrome: Also known as metabolic syndrome, it's a cluster of conditions that increase the risk of heart disease, stroke, and Type 2 diabetes. These conditions are less likely to present acutely as described and are more chronic in nature.