Nocturnal hypoglycemia detected with the Continuous Glucose Monitoring System in pediatric patients with type 1 diabetes

Objective: To use the Continuous Glucose Monitoring System (CGMS, MiniMed, Sylmar, Calif) to determine if bedtime blood glucose levels were associated with the occurrence of nocturnal hypoglycemia. Study design: Patients (n = 47, 18 boys, mean age 11.8 +/- 4.6 years) with type I diabetes used CGMS For 167 nights. Data were analyzed for glucose less than or equal to40 or less than or equal to50 mg/dL, comparing bedtime blood glucose levels of less than or equal to100 or >100 mg/dL and less than or equal to150 or >150 mg/dL. Results: A glucose value of: less than or equal to40 mg/dL occurred on 27% of nights and less than or equal to50 mg/dL on 35% of nights. There was a 2-fold increase (45% vs 22%, P = .015) in the incidence of hypoglycemia with a bedtime glucose : 100 mg/dL and a 1.7-fold increase (46% vs 26%, P = .01) with a value of less than or equal to150 mg/dL; most episodes occurred between 9 I'm and 1 AM. There was no difference in hypoglycemia duration (86.4 minutes For glucose less than or equal to100 mg/dL vs 84.5 minutes for >100 mg/dL, P = NS), and no bedtime glucose value between 110 and 300 mg/dL decreased the incidence of nocturnal hypoglycemia to less than or equal to10%. The incidence of nocturnal hypoglycemia was similar for patients using Insulin pump and injection therapy,, and there was no correlation between hemoglobin A1c and incidence or duration of hypoglycemia. Conclusions: Nocturnal hypoglycemia is frequent, of long duration, associated with bedtime glucose Values less than or equal to 100 to 150 mg/dL, and predominately in the early part of the night. CGMS is a useful tool to diagnose asymptomatic nocturnal hypoglycemia.