Purpose The purpose of our study was to analyze the characteristics of OGTT and the correlation between the insulin to C-peptide molar ratio (ICPR), HOMA-IR and insulin antibodies (IAs) in T2DM patients. Patients and Methods A total of 77 T2DM patients were included and divided into the IA+ group (25 patients) and IA- group (52 patients). The values of serum glucose, insulin, and C-peptide testing during 2-h OGTT were summarized comparatively, and ROC was made to analyze the predictive value of ICPR for IAs. Results At each time point of OGTT, there was no significant difference in serum glucose and C-peptide changes (p>0.05). Serum insulin levels in positive patients were elevated or not at different time points of the OGTT but ICPR was significantly different (P<0.05) in the two groups. Spearman correlation coefficient analysis showed that the presence of insulin antibodies was correlated with ICPR, but not with HOMA-IR, and ICPR-2h had a better prediction capacity (AUC=0.735, the optimal cutoff-point=0.11, Se=0.760, Sp=0.635). Conclusion T2DM patients with IAs showed no difference in serum glucose and serum C-peptide changes, but elevated or not insulin levels on the OGTTs, compared with negative patients. ICPR-2h can be a preliminary diagnostic index to timely predict IAs in T2DM patients.

Purpose This study aimed to further quantify the relationship between insulin antibodies (IAs) and the 2-hour insulin to C-peptide molar ratio (2h-ICPR) using a multiple linear regression model in T2DM patients. Methods A total of 274 T2DM patients from April 2019 to December 2022 in Xiang’an Hospital of Xiamen University were included in this study. Multiple Linear Model Fitting was conducted on the candidate independent variables (age, BMI, HbA1c, and 2h-ICPR) for the multiple linear regression. The linear relationship between insulin antibodies (IAs) and the significant independent variables was presented by making multiple linear regression equations. Results The total demographic characteristics of the included patients were as follows: age (51.92±13.10 years), BMI (24.94±3.99 kg/m 2 ), HbA1c (9.70±2.39%), 2h-ICPR (0.12±0.11), and IAs (0.37±1.12COI). Linear relationships of independent variables: age ( r =0.163, p=0.007), 2h-ICPR ( r =0.259, p=0.001), BMI ( r =0.007, p=0.907) and 2h-ICPR ( r =0.092, p=0.129). Multiple linear regression: age (unstandardized β=0.014, 95% CI: 0.004–0.024, p=0.004), 2h-ICPR (unstandardized β=2.758, 95% CI: 1.555–3.962, p≤0.001). The regression equation: . Conclusion The quantitative relationship between 2h-ICPR and insulin antibodies was . 2h-ICPR can be a preliminary screening indicator for insulin antibody testing in patients with type 2 diabetes.