What IGF-2/IGF-1 ratio is most suggestive of Non-Islet Cell Tumor Hypoglycemia (NICTH)?

33-year-old female with a PMH of obesity, C6 syringomyelia, narcolepsy, fibromyalgia, PTSD, depression, idiopathic intracranial hypertension (pseudotumor cerebri), PCOS, and prediabetes who presents for evaluation of possible hypoglycemia. Labs: HbA1c was 5.3%, Fasting evaluation showed glucose 93 mg/dL, insulin 11.9 µIU/mL, C-peptide 2.91 ng/mL, proinsulin <2 pmol/L, β-hydroxybutyrate 0.12 mmol/L, negative insulin antibodies, and negative sulfonylurea screen. IGF-1 was 213 ng/mL (reference 83–280), and IGF-2 was mildly elevated at 592 ng/mL (reference 180–580).