Todd M. Gross

Performance Evaluation of the MiniMed® Continuous Glucose Monitoring System During Patient Home Use

BACKGROUND The recent availability of a continuous glucose monitor offers the opportunity to match the demands of intensive diabetes management with a period of equally intensive blood glucose monitoring. The present study evaluates the performance of the MiniMed continuous glucose monitoring system (CGMS) in patients with diabetes during home use. METHODS Performance data and demographic information were obtained from 135 patients who were (mean +/- SD) 40.5+/-14.5 years old, had an average duration of diabetes of 18.0+/-9.8 years, 50% were female, 90% were Caucasian, and 87% of whom had been diagnosed with type 1 diabetes. Patients were selected by their physician, trained on the use of the CGMS and wore the device at home for 3 days or more. The performance of the CGMS was evaluated against blood glucose measurements obtained using each patients home blood glucose meter. Evaluation statistics included correlation, linear regression, mean difference and percent absolute difference scores, and Clarke error grid analysis. RESULTS The CGMS values were compared to 2477 SMBG tests (r = 0.91, slope = 0.93, intercept = 14.5 mg/dL, mean absolute difference = 18.0%+/-19.8%). Clarke error grid analysis showed 96.2% of the data pairs falling within the clinically acceptable regions (zones A and B). CONCLUSIONS These results demonstrate the agreement of the CGMS to blood glucose meter values, under conditions of home use, in patients selected by their physicians as candidates for continuous monitoring. The detailed glucose information provided by the CGMS should make successful management of diabetes more easily achieved.

Efficacy and reliability of the continuous glucose monitoring system.

S-19 TIGHT CONTROL OF GLUCOSE has been shown to reduce both microvascular and macrovascular complications of diabetes mellitus,1–3 yet euglycemia is achieved only by a minority of patients.4 Intensive control of blood glucose cannot be achieved without vigilant attention to blood glucose levels.5Consequently, the goal of achieving normoglycemia has stimulated the search for optimal methods of monitoring changes in glucose levels in response to food, exercise, insulin, and antidiabetes medications. When it was first introduced, the technique of self-monitored blood glucose (SMBG) testing of capillary blood via fingerstick represented a major advance in methods of monitoring and improving glycemic control. Now that intensive therapy has become the standard of care for both type 1 and type 2 diabetes, SMBG has been established as a cornerstone of patient management. Current American Diabetes Association (ADA) guidelines recommend SMBG testing at least three to four times each day in patients with type 1 diabetes and at least once a day in patients with type 2 diabetes who cannot be managed with diet and exercise alone.6 Unfortunately, there are many impediments to adequate SMBG practice, including patient education and motivation, as well as improper technique.7,8 But even highly motivated patients who carefully perform frequent fingerstick measurements may miss substantial fluctuations in glucose levels, particularly episodes of nocturnal hypoglycemia. Furthermore, the blood glucose meters that are available today do not consistently achieve either the ADA or the Food and Drug Administration (FDA) goals for meter accuracy.9,10 The recent development of a method for continuously and automatically measuring glucose levels offers a dramatic improvement in the ability to monitor blood glucose—and, thus, intensively manage diabetes. The MiniMed® Continuous Glucose Monitoring System (CGMS, MiniMed Inc., Northridge, CA) is the first commercially available continuous glucose monitor. In this chapter, we summarize the results of a multicenter clinical evaluation of the CGMS, the results of a pilot study demonstrating the efficacy of the CGMS in diabetes management, and the results of a large postmarketing surveillance study confirming the performance of the CGMS during its initial commercial use.

Use of the Continuous Glucose Monitoring System to Guide Therapy in Patients With Insulin-Treated Diabetes: A Randomized Controlled Trial

OBJECTIVE To show improved glycemic control in patients with insulin-treated diabetes after adjustments to the diabetes management plan based on either continuous glucose monitoring using the Continuous Glucose Monitoring System (CGMS) or frequent self-monitoring of blood glucose (SMBG) using a home blood glucose meter. PATIENTS AND METHODS From January to September 2000, patients aged 19 to 76 years with insulin-treated diabetes were assigned to insulin therapy adjustments based on either CGMS or SMBG values. At the end of the study, patients in both groups used the CGMS for 3 days; these values were used to calculate measures of hypoglycemia. Repeated-measures analysis of variance with post hoc comparisons were used to test differences in hemoglobin A1c levels and hypoglycemia between the 2 study groups. RESULTS A total of 128 patients were enrolled in the study. Nineteen discontinued study participation, leaving 51 in the CGMS group and 58 in the SMBG group. No significant differences were noted in demographics or baseline characteristics between the 2 groups. There were no significant differences in hemoglobin A1c levels between the CGMS group and the SMBG group at baseline (9.1% +/- 1.1% vs 9.0% +/- 1.0%, P = .70), and both groups showed statistically significant (P < .001) and similar (P = .95) improvement in hemoglobin A1c levels after 12 weeks of study. However, the CGMS group had a significantly shorter duration of hypoglycemia (sensor glucose, < or = 60 mg/dL) at week 12 of the study (49.4 +/- 40.8 vs 81.0 +/- 61.1 minutes per event, P = .009). CONCLUSION Use of the CGMS to guide therapy adjustments in patients with insulin-treated diabetes reduces the duration of hypoglycemia compared with therapy adjustments guided by SMBG values alone.