Differential Diagnosis
- Single most likely diagnosis:
- Gestational Diabetes Mellitus (GDM) - Although the patient's glucose levels during daily tracking are within a relatively normal range, the 2-hour glucose tolerance test result of 10 mmol/L exceeds the typical threshold for a diagnosis of GDM. The subsequent drop to near hypoglycemic levels could be indicative of an exaggerated insulin response, which is sometimes seen in GDM.
- Other Likely diagnoses:
- Reactive Hypoglycemia - The patient's glucose level drops significantly from 10 mmol/L at 2 hours to 3.3 mmol/L by 2.5 hours during the glucose tolerance test, suggesting an excessive insulin release in response to glucose ingestion.
- Insulin Resistance with Normal Glucose Tolerance - Despite the abnormal glucose tolerance test result, the patient's daily glucose logs show relatively normal glucose levels, which might indicate insulin resistance without overt diabetes.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
- Insulinoma - Although rare, an insulinoma (a tumor of the pancreas that produces excess insulin) could cause the observed pattern of glucose elevation followed by a significant drop. This condition would require prompt diagnosis and treatment to avoid severe hypoglycemic episodes.
- Other Pancreatic Pathologies (e.g., pancreatic neuroendocrine tumors) - Similar to insulinoma, other rare pancreatic tumors could lead to abnormal glucose regulation and should be considered in the differential diagnosis.
- Rare diagnoses:
- Late-Onset Congenital Hyperinsulinism - A rare condition characterized by excessive insulin secretion, which could lead to the observed glucose patterns. However, this diagnosis is more typical in neonates and young children.
- Other Endocrine Disorders (e.g., adrenal insufficiency, hypopituitarism) - Certain endocrine disorders can affect glucose metabolism, although they are less likely to present with the specific pattern of glucose elevation followed by a drop as seen in this patient.