Continuous Glucose Monitoring and Intensive Treatment of Type 1 Diabetes

Background:  Continuous glucose monitoring has not been established in patients with type 1 diabetes, but blood glucose monitoring is an important part of diabetes management and should be included in an intensive treatment regimen to achieve target hemoglobin levels (A1C).  

Objective:  The purpose of the study was to determine the value of continuous glucose monitoring in the management of type 1 diabetes mellitus.

Methods:  The study was a multi-center, randomized open label trial conducted at 10 centers in the United States.  Patients were eligible for enrollment if they were > 8 years old, had received a diagnosis of type 1 diabetes one year before randomization, either used an insulin pump or received at least 3 daily insulin injection, had a A1C level of 7.0% to 10%, and have been performing home blood glucose monitoring at least 3 times a day.  Three-hundred and twenty-two patients were randomized to use either one of the three continuous glucose monitors (165 patients) or a blood glucose meter and test strips (157 patients). Patients were then divided into three age groups within the experimental and control groups.  Patients were 25 years and older (98 patients), 15-24 years of age (110 patients) and 8-14 years of age (114 patients).  Hemoglobin levels were assessed at baseline and weeks 13 and 26. Power was assessed to be 90 % in this study. The primary outcome measure for this study was a change in the mean hemoglobin level from baseline to 26 weeks.  Secondary endpoints included: a relative decrease in A1C of > 10% at 26 weeks, 26 week A1C levels of less than 7%, an absolute decrease of A1C < 0.5%, a relative increase of A1C > 10%, an absolute increase of A1C > 0.5%, adverse events and frequency of sensor use.

Results:  There was a significant between-group difference in the change of A1C seen in patients that are 25 years and older (mean difference in change -0.53%; 95% Confidence interval [CI], -0.71 to -0.35; P<0.001) but no significant difference in those 15 to 24 years of age (0.08%; 95% CI, -0.17 to 0.33; P=0.52) nor in the 8 to 14 years age group (-0.13%; 95% CI, -0.38 to 0.11; P=0.29).  With regards to the secondary endpoints, at week 26 the 25 and older continuous monitoring group had improvements in almost all measures of glycemic control compared to the control group.  The patients in the continuous monitoring group age 15-24 had no significant improvements over the control group and patients in the 8-14 age group had no significant improvements over the control group except more patients had a reduction of 10% or more in their A1C levels from baseline (P=0.04).  The authors concluded that continuous glucose monitoring can be associated with improved glycemic control in adults with type 1 diabetes and that further work is needed to identify barriers to the effectiveness of continuous monitoring in children and adolescents.

Strengths:  The study had potential for conflict of interest but these conflicts did not appear to affect or influence the study’s objective, methods or conclusions. They reported on hypoglycemia and other adverse events and the rationale of the study was appropriate. 

Weaknesses:  The study was not blinded.  The majority of the study’s patient/guardian population was Caucasian and college educated and the patients had better than average hemoglobin levels for patients with type 1 diabetes.  This may limit the applicability of the results to the general population. The study would have been stronger if they took patients diet and exercise routines into account.  Compliance was not discussed.

Conclusion:  Continuous glucose monitoring is associated with improved glycemic control in adults over age 25 with type 1 diabetes but further studies are needed to determine their effectiveness in children, adolescents and young adults.  It is important to note that currently continuous glucose monitors are not as accurate as blood glucose meters.

Beck RW, Chase HP, Giallo-Scharer L, Messer V, Tamborland WV, et al. Continuous Glucose Monitoring and Intensive Treatment of Type 1 Diabetes. N Engl J Med 2208;359:1464-76.

Nereah Wakala, Pharm D. Candidate