Characteristics of OGTT and Correlation Between the Insulin to C-Peptide Molar Ratio, HOMA-IR, and Insulin Antibodies in T2DM Patients

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.