Background Refeeding syndrome occurs after the reintroduction of feeding after a period of starvation. Hyperglycemia and insulin resistance are known consequences of refeeding syndrome, which is an acute condition that usually resolves after the establishment of nutritional requirements. We describe a patient with severe malnutrition who developed persistent hyperglycemia after refeeding, and no other explanation can be found for his condition.

Case Report(s) An 18-year-old male was admitted with severe malnutrition due to an avoidant- restrictive food intake disorder. He developed hyperglycemia (BGM > 400 mg/dL) with glucosuria and ketonuria on day 22 of refeeding. He has a two-generation family history of diabetes. His weight was 36.2 kg (Z-score -5.3), his height was 166.8 cm (Z-score -1.5), and his BMI was 13.2 (Z-score -6.2). There were no signs of insulin resistance. His investigation showed HbA1c 6.4%, a high insulin level of 55.3 mlU/mL and a high c-peptide level of 5.4 ng/mL (normal level: 1.1–5 ng/dl), and autoantibodies were negative (GAD-65, IA-2, Insulin, ZnT8). He was started on an MDI regimen (Lantus 10 units, an ICR of 0.5 u/8 g, and an ISF of 0.5 u/40 mg/dL above a target of 100 mg/dl). He was discharged on nutritional support and insulin. He stopped insulin after 2 months due to hypoglycemia without medical consultation. His subsequent visits showed improvement in weight gain current weight is 52 kg (Z- score -1.8), BMI: 18.7 (Z score -1.3), and persistence of postprandial hyperglycemia (BGM 200–300 mg/dl) with normal FBG 80–100 mg/dl and HbA1c 4.7–5.5%. His genetic testing for MODY is pending.

Conclusion(s) Hyperglycemia and refeeding syndrome are known associations in the literature, but there is a paucity of information regarding this condition. Our patient developed persistent hyperglycemia after severe malnutrition and nutritional rehabilitation. There is still no established explanation for his conditions since T1DM was rolled out.