Prolonged Fasting Hypoglycemia Due to Insulin Antibodies in Patient With Non-Insulin-Dependent Diabetes Mellitus: Effect of Insulin Withdrawal on Insulin-Antibody—Binding Kinetics

Fasting hypoglycemia, which persisted for 3 days after insulin treatment was stopped,occurred in a patient with non-insulin-dependent diabetes mellitus who had inappropriate plasma free-insulin levels (18–25 μU/ml) and extremely high antibody-bound insulin (>20,000 μU/ml) but normal counterregulatory hormone secretion and plasma C-peptide levels. The amount of antibody-bound insulin decreased in a biphasic pattern over13 mo of observation with an initial half-life of 35 days and a more gradual decrease with a half-life of 160 days. The number of high-affinity antibody binding sites was virtually identical to the amount of antibody-bound insulin in the patient's plasma. We conclude that the patient's fasting hyperinsulinemia and hypoglycemia were due to release of antibody-bound insulin.