Improvement in Glycemic Excursions With a Transcutaneous, Real-Time Continuous Glucose Sensor
A randomized controlled trial
- Satish Garg, MD1,
- Howard Zisser, MD2,
- Sherwyn Schwartz, MD3,
- Timothy Bailey, MD4,
- Roy Kaplan, MD5,
- Samuel Ellis, PHARMD1 and
- Lois Jovanovic, MD2
- 1Barbara Davis Center for Childhood Diabetes, University of Colorado Health Sciences Center, Denver, Colorado
- 2Sansum Diabetes Research Institute, Santa Barbara, California
- 3Diabetes & Glandular Disease Research Associates, San Antonio, Texas
- 4North County Endocrine Group, Escondido, California
- 5East Bay Clinical Trial Center, Concord, California
- Address correspondence and reprint requests to Satish Garg, MD, Professor of Medicine and Pediatrics, Barbara Davis Center for Childhood Diabetes, University of Colorado Health Sciences Center, 1775 N. Ursula St., A140, Aurora, CO 80010. E-mail:
OBJECTIVE—Hypoglycemia and wide glucose excursions continue to be major obstacles to achieving target HbA1c values and the associated reductions in long-term complications (and economic costs) in people with insulin-treated diabetes. In this study we evaluated the accuracy, safety, and clinical effectiveness of a continuous glucose-sensing device.
RESEARCH DESIGN AND METHODS—A total of 91 insulin-requiring patients with type 1 (n = 75) and type 2 (n = 16) diabetes were enrolled in this multicenter randomized study. Subjects wore a transcutaneous, 3-day, continuous glucose-sensing system for three consecutive 72-h periods. Subjects were randomly assigned (1:1 ratio) to either a control group (continuous glucose data not provided) or a display group (continuous glucose data not provided during period 1 but displayed during periods 2 and 3). During periods 2 and 3, patients in the display group had real-time access to sensor glucose values, could review glucose trends over the preceding 1, 3, and 9 h, and were provided with high (≥200 mg/dl) and low (≤80 mg/dl) alerts and a low (≤55 mg/dl) alarm. Sensors were inserted by patients, and both groups used (or wore) the system during daily activities. Device accuracy was assessed by comparing continuous glucose values to paired self-monitoring of blood glucose (SMBG) meter readings. Clinical effectiveness was evaluated by analyzing between-group (control vs. display, periods 2 and 3) and within-group (display, period 1 vs. period 3) differences in time spent in high, low, and target (81–140 mg/dl) glucose zones.
RESULTS—When prospective, real-time sensor values were compared with SMBG values, 95.4% of 6,767 paired glucose values fell within Clarke error grid A and B zones. Pearson’s correlation coefficient was 0.88, and mean and median absolute relative differences were 21.2 and 15.9%, respectively. No systematic bias was detected at any of the prespecified glucose levels (50, 80, 100, 150, and 200 mg/dl). When compared with control subjects, the display group spent 21% less time as hypoglycemic (<55 mg/dl), 23% less time as hyperglycemic (≥240 mg/dl), and 26% more time in the target (81–140 mg/dl) glucose range (P < 0.001 for each comparison). Nocturnal (10:00 p.m. to 6:00 a.m.) hypoglycemia, as assessed at two thresholds, was also reduced by 38% (<55 mg/dl; P < 0.001) and 33% (55–80 mg/dl; P < 0.001) in the display group compared with control subjects.
CONCLUSIONS—We conclude that real-time continuous glucose monitoring for periods up to 72 h is accurate and safe in insulin-requiring subjects with type 1 and type 2 diabetes. This study demonstrates that availability of real-time, continuously measured glucose levels can significantly improve glycemic excursions by reducing exposure to hyperglycemia without increasing the risk of hypoglycemia, which may reduce long-term diabetes complications and their associated economic costs.
- ARD, absolute relative difference
- DCCT, Diabetes Control and Complications Trial
- SMBG, self-monitoring of blood glucose
- Received September 8, 2005.
- Accepted October 3, 2005.
- DIABETES CARE