Improved glucose excursions using an implantable real-time continuous glucose sensor in adults with type 1 diabetes

OBJECTIVE- The capability of emerging glucose sensor technology to continuously monitor glucose levels may provide ways to achieve glycemic targets while reducing hypoglycemia. RESEARCH DESIGN AND METHODS- A first-generation, long-term continuous glucose sensor (DexCom, San Diego, CA) was implanted subcutaneously in 15 patients with type 1 diabetes. Safety, efficacy, and potential benefits were evaluated during a blinded control period and in a study period during which patients had real-time access to the glucose data. RESULTS- The bias differences between self-monitored blood glucose (SMBG) and sensor data were < 15% at 2.8, 4.4, 5.6, 8.3, and 11.1 mmol/l. No procedure or device-related adverse events were observed. Of 15 patients, 13 (87%) had functional sensors during the 12-h simulated home use study with 96% of points in the A and B regions of the Clarke error grid, an R value of 0.88, and a mean absolute relative difference of 16% when retrospectively compared with SMBG. In actual home use, during the blinded control period (50 +/- 16 days) data were not displayed to the patient, whereas during the unblinded study period (44 +/- 17 days) the data were presented to the patient, and alerts were set at 3.1, 5.6, and 11.1 mmol/l. Patients spent a median of 47% less time below 3.1 mmol/l (P < 0.05) and 25% less time above 13.3 mmol/l (P < 0.05) during the nonblinded study period compared with the blinded control period. CONCLUSIONS- The availability of real-time continuous glucose values may help patients reduce their hyperglycemic excursions and lower the risk of hypoglycemia.