Intravenous glucose tolerance test and anti-GAD65 antibodies in the diagnosis of the type of diabetes mellitus

The aim of the present study was to evaluate the importance of the phases of insulin secretion, measured during an intravenous glucose tolerance test (IVGTT), and anti‐GAD65 antibodies as a beta‐cell autoimmune marker, in the proper early diagnosis of the type of diabetes in normal‐weight patients aged 30–45 years. Forty‐two newly diagnosed diabetic patients (25 males and 17 females), of mean age 37.2±6.9 years and BMI 24.4±2.7kg/m2, were enrolled in the study; 19 subjects with normal glucose tolerance, of mean age 36.8±7.4 years and mean BMI 24.3±2.3 kg/m2, served as a control group. Using the data from IVGTT and anti‐GAD65 antibodies, the diabetic patients were divided into two groups—type 1 diabetic patients (n=19), showing loss of first (FPIS) and second (SPIS) phases of insulin secretion: 12.9±5.1mU/L versus 134.4±43.7mU/L in the control group, p < 0.001; and 15.4±6.4mU/L versus 64.4±23.6mU/L in the control group, p