From the Research
For a patient with severe persistent hypoglycemia, the initial lab workup should include a comprehensive metabolic panel, complete blood count, and a critical sample drawn during a hypoglycemic episode that includes plasma glucose, insulin, C-peptide, proinsulin, beta-hydroxybutyrate, and sulfonylurea screen, as recommended by the most recent guidelines 1. The initial workup is crucial in determining the underlying cause of hypoglycemia.
- A comprehensive metabolic panel can help identify any electrolyte imbalances or kidney function abnormalities that may be contributing to hypoglycemia.
- A complete blood count can help identify any underlying infections or inflammatory conditions that may be causing hypoglycemia, as suggested by a recent literature review on the usefulness of complete blood count in assessing cardiovascular and metabolic diseases 2.
- The critical sample drawn during a hypoglycemic episode should include plasma glucose, insulin, C-peptide, proinsulin, beta-hydroxybutyrate, and sulfonylurea screen to differentiate between exogenous insulin administration, endogenous hyperinsulinism, and other metabolic disorders causing hypoglycemia. Additional tests that may be necessary include:
- Insulin antibodies to evaluate for autoimmune causes of hypoglycemia
- Cortisol, growth hormone, and glucagon levels to evaluate for endocrine disorders
- Measuring IGF-1, IGF-2, and their ratio to help identify non-islet cell tumors
- Genetic testing for suspected hereditary conditions like insulinomas or genetic defects in insulin regulation
- Imaging studies such as CT, MRI, or endoscopic ultrasound if an insulinoma or other tumor is suspected, as discussed in a recent review on hypoglycemia in diabetes 3. The timing of sample collection during hypoglycemia is crucial, as it provides the most diagnostic information when hormonal counter-regulatory responses are active, and continuous glucose monitoring (CGM) can be useful in detecting hypoglycemia, especially in patients with impaired awareness of hypoglycemia, as shown in a recent study on CGM-recorded hypoglycemia 4.