When carrying out medical examinations, we often encounter the so-called“steeptype plasma glucose subjects”who show a high value of 1-hour postprandial plasmaglucose (1-hr PPG). Therefore, it is considered that there is a possibility of large dispersion of the difference or the change ratio of plasma glucose before and after test medicine is given to subjects in order to carry out a test without the classification of diabetes mellitus for the subjects of diabetes mellitus (DM) or impaired glucose tolerance (IGT) especially in the clinical test of a phase one study. Here, it is considered whether or not subjects are required to be classified by DM, by carrying out 75 g oral glucose tolerance test (OGTT) which is widely acknowledged and applied as the most leading diagnostic method of DM when the clinical study of a cure for DM is carried out.
This particular research included 125 men who were judged to be healthy in the medical examination. Their average age was 32.6±5.1 (mean±SD). As a metabolic function test for plasma glucose, 75 g OGTT was given, and the values of FPG, 1-hr PPG, and 2-hr PPG were measured. Simultaneously, the measurement of HbA
1c was carried out. In terms of the classification of 75 g OGTT (OGTT type), the Japan Diabetes Society (JDS) classified the type based upon“The Classification and Diagnostic Criteria of Diabetes Mellitus”which was revised in May 1999 as follows: JDS classified normal glucose tolerance (NGT-1) into a group of both normal type and a 1-hour value of less than 180 mg/dl. Also, JDS classified NGT-2 into a group of a 1-hour value of more than 180 mg/di after plasma glucose loading in the normal type defined by JDS.
When the proportion of both FPG and OGTT type based upon HbA
1c was examined, 1-hr PPG became 212.6±5.4 (mean±SE) mg/dl in NGT-2 and 203.0±8.0 mg/dl in IGT, respectively. Compared with FPG and 2-hr PPG, no remarkable difference was found between the values of both NGT-2 and IGT in 1-hr PPG. Also, 98 subjects (78.4%) out of all 125 subjects showed both FPG<110 mg/dl and HbA
1c≤5.8%. The details of this particular result are as follows: NGT-1 59 subjects (60.2%), NGT-2 18 subjects (18.4%), IGT 18 subjects (18.4%), and DM 3 subjects (3.1%). Furthermore, 36 subjects aged 20-29 were examined similarly and the results showed NGT-1 18 subjects (50.0%), NGT-2 4 subjects (11.1%), IGT 5 subjects (13.9%), and DM 9 subjects (25.0%).
In conclusion, in the clinical study of a cure for diabetes mellitus, it is important to classify subjects for diabetes mellitus in order to grasp the dispersion of test data more precisely as one of the means. Also, just like IGT, attention must be given to the indication of a high value of 1-hr PPG under the management of a clinical study even if 1-hr PPG is considered to be the normal type in the above diagnostic criteria.
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