Continuous glucose monitoring in children with type 1 diabetes.

OBJECTIVE: To examine the feasibility of daily use of a continuous glucose monitor, the FreeStyle Navigator Continuous Glucose Monitoring System ("Navigator"), in children with type 1 diabetes (T1D). STUDY DESIGN: After a masked Navigator was used for 4 to 7 days to establish a baseline level of glycemic control, 30 insulin pump users with T1D (average age 11.2 years) were asked to use the Navigator daily for 13 weeks. RESULTS: Subjects averaged 149 h/wk of Navigator use during the first 4 weeks, which decreased slightly to 134 h/wk during weeks 9 to 13 (P = .006). Mean hemoglobin A1c improved from 7.1% at baseline to 6.8% at 13 weeks (P = .02), and the percentage of glucose values between 71 and 180 mg/dL increased from 52% to 60% (P = .01). Subjects and parents reported high satisfaction with the Navigator on the Continuous Glucose Monitor Satisfaction Scale. Two subjects had severe skin reactions related to sensor mount adhesive. CONCLUSION: This study indicates that incorporating real-time continuous glucose monitoring into the daily treatment of children with T1D is feasible. The results provide a compelling rationale for conducting a randomized trial of daily use of a continuous glucose monitor in children with T1D.

Impact of exercise on overnight glycemic control in children with type 1 diabetes mellitus.

OBJECTIVE: To examine the effect of exercise on overnight hypoglycemia in children with type 1 diabetes mellitus (T1DM). STUDY DESIGN: At 5 clinical sites, 50 subjects with T1DM (age 11 to 17 years) were studied in a clinical research center on 2 separate days. One day included an afternoon exercise session on a treadmill. On both days, frequently sampled blood glucose levels were measured at the DirecNet central laboratory. Insulin doses were similar on both days. RESULTS: During exercise, plasma glucose levels fell in almost all subjects; 11 (22%) developed hypoglycemia. Mean glucose level from 10 pm to 6 am was lower on the exercise day than on the sedentary day (131 vs 154 mg/dL; P=.003). Hypoglycemia developed overnight more often on the exercise nights than on the sedentary nights (P=.009), occurring on the exercise night only in 13 (26%), on the sedentary night only in 3 (6%), on both nights in 11 (22%), and on neither night in 23 (46%). Hypoglycemia was unusual on the sedentary night if the pre-bedtime snack glucose level was>130 mg/dL. CONCLUSIONS: These findings indicate that overnight hypoglycemia after exercise is common in children with T1DM and support the importance of modifying diabetes management after afternoon exercise to reduce the risk of hypoglycemia.

Lack of accuracy of continuous glucose sensors in healthy, nondiabetic children: results of the Diabetes Research in Children Network (DirecNet) accuracy study.

OBJECTIVE: The workup of hypoglycemia requires frequent glucose sampling. We designed these studies to determine if the Continuous Glucose Monitoring System (CGMS) and the GlucoWatch G2 Biographer (GW2B) are sufficiently accurate to use in nondiabetic children. Study design Fifteen healthy children (aged 9-17 years, 11 boys) wore a GW2B and a CGMS during a 24-hour period, and reference serum glucose was measured hourly during the day and half-hourly overnight. RESULTS: Compared with the reference glucose, the median absolute difference in concentrations measured by the GW2B (487 pairs) was 13 mg/dL, and the difference measured by the CGMS was 17 mg/dL (668 pairs), with 30% and 42% of values using the GW2B and CGMS, respectively, deviating >20 mg/dL from the reference value. The GW2B reported values <60 mg/dL in 73% of subjects, the CGMS in 60% of subjects. In none of these episodes was serum glucose truly low. Spurious high glucose concentrations also were observed with the sensors. The mean reference glucose was lowest at 5 am (89 mg/dL) and highest at 11:30 pm (106 mg/dL) during the 24-hour period. CONCLUSIONS: Neither the CGMS nor the GW2B is accurate enough to establish population standards of the glycemic profile of healthy children and cannot be recommended in the workup of hypoglycemia in nondiabetic youth.