Table 1.
Laboratory Investigations Performed in Our Patient with Insulin Autoimmune Syndrome (IAS)
| Analyte | Patient Result | Reference Range |
|---|---|---|
| During a spontaneous episode of symptomatic hypoglycemia | ||
| Serum glucose | 2.5 mmol/L (45 mg/dL) | 3.6–7.8 mmol/L |
| β-hydroxybutyrate | < 0.30 mmol/L (< 3.1 mg/dL) | < 0.30 mmol/L |
| Insulin | 54,930 pmol/L (7,909 μIU/mL) | < 10 pmol/L when glucose ≤ 2.7 mmol/L |
| C-peptide | 4,104 pmol/L (12.4 ng/mL) | 230–990 pmol/L |
| Insulin/C-peptide molar ratio | 13.4 | < 1 |
| Selective arterial calcium stimulation test | ||
| Insulin (all specimens) | > 34,000 pmol/L (> 4,895 μIU/mL) | – |
| C-peptide (all specimens) | > 5,000 pmol/L (> 15 ng/mL) | – |
| Other laboratory test results | ||
| Liver function | Unremarkable | – |
| Kidney function | Unremarkable | – |
| Hemoglobin A1c | 5.4 % | 4.8–6.2 % |
| ACTH stimulation test | Adequate cortisol response | – |
| Heterophile antibodies | Negative | – |
| Insulin autoantibodies | > 50 kU/L (> 50 U/mL) | < 0.4 kU/L |
| Rheumatoid factor | < 30 IU/mL | < 30 IU/mL |
| Antinuclear antibodies | Negative | – |
| Serum protein electrophoresis | No paraprotein detected | – |