Glucose sensor evaluation of glycemic instability in pediatric type 1 diabetes mellitus.
Maintaining blood glucose (BG) levels within the target range can be an elusive goal in children with type 1 diabetes mellitus (DM). To identify factor(s) that may contribute to glycemic instability, we analyzed the Continuous Glucose Monitoring System (CGMS) (Medtronic MiniMed, Northridge, CA) profiles of a group of children with type 1 DM and a history of frequent BG fluctuations and hypoglycemia. A total of 30 (17 girls, 13 boys) pediatric patients with a history of frequent BG fluctuations and hypoglycemia (mean age, 10.5 +/- 0.7 years; duration, 5.0 +/- 0.6 years), on three to four injections of insulin daily or insulin pump therapy, were evaluated by the CGMS. The mean BG (MBG), absolute means of daily differences (MODD), mean amplitude of glycemic excursion (MAGE), and number of hypoglycemic events (BG <60 mg/dL) for 48 h were calculated in each patient. There was a significant correlation between MBG and glycosylated hemoglobin (HbA1c) (r(2) = 0.22, p < 0.009). There was also a significant correlation between severity of lipohypertrophy and glycemic control (HbA1c) (r(2) = 0.20, p < 0.01). The MODD values had a positive correlation with the severity of injection site lipohypertrophy (r(2) = 0.37, p < 0.0003). The MAGE values had a positive correlation with bolus:basal insulin ratio (r(2) = 0.22, p < 0.009) and number of hypoglycemic events (r(2) = 0.21, p < 0.008), independent of age, MBG, and glycemic control. The 48-h CGMS profile can help characterize day-to-day and within-day BG variability and identify factors influencing glycemic instability in pediatric type 1 DM.