The Continuous Glucose Monitoring System Is Useful for Detecting Unrecognized Hypoglycemias in Patients With Type 1 and Type 2 Diabetes but Is Not Better Than Frequent Capillary Glucose Measurements for Improving Metabolic Control

OBJECTIVE: To evaluate whether the continuous glucose monitoring system (CGMS; MiniMed, Sylmar, CA) is useful for investigating the incidence of unrecognized hypoglycemias in type 1 and type 2 diabetic patients and for improving metabolic control in type 1 diabetic patients. RESEARCH DESIGN AND METHODS: A total of 70 diabetic subjects (40 type 1 and 30 type 2 subjects) were monitored using the CGMS. The number of unrecognized hypoglycemias was registered. Furthermore, the 40 type 1 diabetic patients whose treatment was modified in accordance with the information obtained from the CGMS were compared with a control group of 35 different type 1 diabetic patients using intensive capillary glucose measurements. HbA(1c) levels were measured before the monitoring period and 3 months later. RESULTS: The CGMS detected unrecognized hypoglycemias in 62.5% of the type 1 diabetic patients and in 46.6% of the type 2 diabetic patients. We found that 73.7% of all events occurred at night. HbA(1c) concentrations decreased significantly in both the group of type 1 diabetic subjects monitored with the CGMS (from 8.3 +/- 1.6 to 7.5 +/- 1.2%, P < 0.01) and the control group (from 8.0 +/- 1.4 to 7.5 +/- 0.8%, P < 0.01). The greatest reduction was observed in the subgroup of patients who started continuous subcutaneous insulin infusion therapy, both in the CGMS-monitored and control groups (from 9.4 +/- 2 to 7.2 +/- 1.4% and from 8.1 +/- 1.8 to 7.1 +/- 0.6%, respectively). CONCLUSIONS: The CGMS is useful for detecting unrecognized hypoglycemias in type 1 and type 2 diabetic subjects; however, it is not better than standard capillary glucose measurements for improving metabolic control of type 1 diabetic subjects, regardless of the therapeutic regimen.