Relationship of Fasting and Hourly Blood Glucose Levels to HbA1c Values
Safety, accuracy, and improvements in glucose profiles obtained using a 7-day continuous glucose sensor
- Satish Garg, MD1 and
- Lois Jovanovic, MD2
- 1Barbara Davis Center for Childhood Diabetes, University of Colorado at Denver and Health Sciences Center, Aurora, Colorado
- 2Sansum Diabetes Research Institute, Santa Barbara, California
- Address correspondence and reprint requests to Satish Garg, MD, Professor of Medicine and Pediatrics, Barbara Davis Center for Childhood Diabetes, University of Colorado at Denver and Health Sciences Center, 1775 N. Ursula St. A140, Aurora, CO 80010. E-mail: satish.garg{at}uchsc.edu
Abstract
OBJECTIVE—In this study, we evaluated the safety and efficacy of 7-day transcutaneous, real-time, continuous glucose monitoring (CGM) in subjects with insulin-requiring diabetes.
RESEARCH DESIGN AND METHODS—Eighty-six subjects were enrolled at five U.S. centers. Subjects wore a sensor inserted under the skin of the abdomen for 7 days during each of three consecutive periods. Data were blinded during period 1 and unblinded during periods 2 and 3.
RESULTS—Of the 6,811 matched self-monitoring of blood glucose to sensor values prospectively analyzed, 97.2% fell in the Clarke error grid zones A and B, and median absolute relative difference was 11.4%. After unblinding, subjects reduced time spent at <55 mg/dl by 0.3 h/day, reduced time spent at >240 mg/dl by 1.5 h/day, and increased time in the target zone (81–140 mg/dl) by 1.4 h/day (P < 0.05 for all three comparisons). Improvements were seen in both types 1 and 2 diabetes and with use of both multiple daily injections and continuous subcutaneous insulin infusion. Modal day graphs were generated in six groups of subjects based on HbA1c (A1C) (≤6, 6–7, 7–8, 8–9, 9–10, and >10%). Mean glucose levels from midnight to 7:00 a.m. (fasting and dawn phenomenon periods) were only normal for subjects with A1C ≤6%. All other groups were hyperglycemic during this and all periods. Reductions in overall mean glucose were achieved for the four highest A1C groupings with unblinded device use.
CONCLUSIONS—This is the first report of a real-time, transcutaneous glucose sensor that functioned for 7 days. The use of CGM in the unblinded phase resulted in improvements in target-range glycemia across all A1C values.
- ARD, absolute relative difference
- CGM, continuous glucose monitoring
- CSII, continuous subcutaneous insulin infusion
- MDI, multiple daily injections
- SMBG, self-monitoring of blood glucose
Footnotes
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S.G. and L.J. have received research funding to their respective institutes from DexCom, are on the advisory board for DexCom, and have received honoraria for various educational activities from DexCom.
A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances.
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C Section 1734 solely to indicate this fact.
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- Accepted August 28, 2006.
- Received June 30, 2006.
- DIABETES CARE
