Analysis of 24-Hour Glycemic Excursions in Patients with Type 1 Diabetes by Using Continuous Glucose Monitoring

Background: Little information is available regarding postprandial glycemic excursions and hypoglycemia in Japanese patients with type 1 diabetes (T1D). Methods: Four male and eight female patients who were on intensive therapy with rapid-acting insulin plus basal insulin underwent retrospective continuous glucose monitoring (CGM). Clinical characteristics (median) of the patients were as follows: age, 40.5 years; body mass index, 22.2 kg/m(2); urinary C-peptide, 0.75 mu g/day; hemoglobin A1c (HbA1c) after 2 months of CGM, 6.5%; and total insulin dose, 40.0 units. Results: The largest glycemic excursions were observed after breakfast. The time intervals from the start of each meal to the highest postprandial glucose levels peaked at 65-100 min. Hypoglycemia (blood glucose <70 mg/dL) was observed for more than 100 min per 24-h period. HbA1c and 24-h mean glucose levels were significantly correlated (r = 0.727, P = 0.007). The 12 participants were divided into two groups by HbA1c level after 2 months: those whose HbA1c exceeded the median of HbA1c (HbA1c > 6.5%) (n = 6) and those whose HbA1c fell below the median (HbA1c < 6.5%) (n = 6). The premeal glucose levels/the highest postprandial glucose levels after breakfast were insignificantly higher in the HbA1c > 6.5% group (183/247 mg/dL, respectively) than in the HbA1c < 6.5% group (117/221mg/dL, respectively). The duration of hypoglycemia lasted longer in the HbA1c < 6.5% group, with these episodes often occurring during the nighttime. Conclusions: These findings suggest that preventing nighttime hypoglycemia and correcting glucose spikes after breakfast are required in patients with T1D receiving intensive therapy to stabilize and improve glycemic control.