24-Hour Glycemic Variations in Drug-Naïve Patients with Type 2 Diabetes: A Continuous Glucose Monitoring (CGM)-Based Study

OBJECTIVE To investigate a 24-hour glycemic variation in drug-naïve, type 2 diabetic patients by using CGM. METHODS A total of 30 inpatients with type 2 diabetes were included in the study to analyze the 24-hour CGM data. RESULTS The patients' median age was 58 years old (interquartile range: 42-66 years), and their median HbA1c value was 7.6 (6.7-8.8)%. The median time to postprandial peak glucose levels(Peak Time) for each meal was 70-85 minutes, with the range of postprandial glucose increases(Increase Range) for each meal being 83-109 mg/dL. There was a significant positive correlation between the HbA1c values and Increases Range, Peak Time observed after breakfast and dinner, respectively. When the patients were stratified by a median HbA1c value of 7.6% into 2 groups, Increases Range and Peak Time, after breakfast, were shown to be significantly higher in the high-HbA1c group (H) than in the low-HbA1c (L) group. When the subjects were divided into four groups according to HbA1c levels:1 (<7.0%, n = 8), 2 (7.0-7.9%, n = 8), 3 (8.0-8.9%, n = 8), and 4 (≥9%, n = 6), the average glucose level, pre-meal glucose level and postprandial peak glucose level increased steadily from group 1 to 4 in a stepwise manner. CONCLUSIONS In drug-naïve, Japanese type 2 diabetic patients, the Peak Time and the Increase Range were maximal after dinner. It was shown that the greater the HbA1c values, the longer Peak time and the higher Increase Range after breakfast and dinner. The average glucose level, pre meal glucose level and postprandial peak glucose level increased steadily as HbA1c level increased.