Insulin/C-peptide molar ratio is not influenced by plasma glucose level in patients with EIAS

Abstract Background Exogenous insulin antibody syndrome (EIAS) can lead to induction of insulin antibody and sequentially recurrent hypoglycemia in patients with type 2 diabetes mellitus (T2DM). Insulin to C-peptide molar ratio (I/C ratio) is used to judge the reason of hypoglycemia when it occurs, however its change under different glucose level in EIAS is unknown. Methods Data from patients with T2DM and EIAS who were admitted to the department of endocrinology were retrospectively analyzed from January 2018 to March 2020. Results A total of 16 patients with T2DM and EIAS were included. All patients reported symptoms of hypoglycemia. The average age of the EIAS patients was 65.7 ± 9.6 years, and the average duration of diabetes was 14.2 ± 7.3 years. Among these patients, 6 were using Novolin 30R, 4 were using with Humalog Mix 25, 2 were using with Novolin N, NovoMix30, Humalog and Lantus, respectively. Patients were then divided into one group with detected hypoglycemia and the other group with undetected hypoglycemia. No significant differences were observed between the two groups in terms of liver and kidney functions, hemoglobin and HbA1c. Similarly, no differences were found in levels of insulin and C-peptide, as well as I/C ratio when the glucose level changed. All 16 patients ceased insulin therapy, and no hypoglycemia occurred after transition to oral drugs. Conclusion I/C ratio is not influenced by plasma glucose level in patients with T2DM and EIAS. Therefore, it could be tested regardless of glucose level in patients with EIAS.