Factors Predictive of Use and of Benefit From Continuous Glucose Monitoring in Type 1 Diabetes

OBJECTIVE

To evaluate factors associated with successful use of continuous glucose monitoring (CGM) among participants with intensively treated type 1 diabetes in the Juvenile Diabetes Research Foundation Continuous Glucose Monitoring Randomized Clinical Trial.

RESEARCH DESIGN AND METHODS

The 232 participants randomly assigned to the CGM group (165 with baseline A1C ≥7.0% and 67 with A1C <7.0%) were asked to use CGM on a daily basis. The associations of baseline factors and early CGM use with CGM use ≥6 days/week in the 6th month and with change in A1C from baseline to 6 months were evaluated in regression models.

RESULTS

The only baseline factors found to be associated with greater CGM use in month 6 were age ≥25 years (P < 0.001) and more frequent self-reported prestudy blood glucose meter measurements per day (P < 0.001). CGM use and the percentage of CGM glucose values between 71 and 180 mg/dl during the 1st month were predictive of CGM use in month 6 (P < 0.001 and P = 0.002, respectively). More frequent CGM use was associated with a greater reduction in A1C from baseline to 6 months (P < 0.001), a finding present in all age-groups.

CONCLUSIONS

After 6 months, near-daily CGM use is more frequent in intensively treated adults with type 1 diabetes than in children and adolescents, although in all age-groups near-daily CGM use is associated with a similar reduction in A1C. Frequency of blood glucose meter monitoring and initial CGM use may help predict the likelihood of long-term CGM benefit in intensively treated patients with type 1 diabetes of all ages.Despite recent advances in insulin delivery and home blood glucose monitoring, many individuals with type 1 diabetes fail to achieve recommended A1C target levels (1,2). Further, hypoglycemia is a problem for many patients with type 1 diabetes (3) and can be a significant deterrent to achieving and maintaining tight glycemic control (4,5). Thus, the introduction of real-time continuous glucose monitoring (CGM) systems was received with great interest because these devices may have the potential to increase the proportion of patients who are able to maintain target A1C values while simultaneously limiting their risk of severe hypoglycemia. The first real-time CGM device, the GlucoWatch Biographer (6), was difficult to use, in large part because of skin reaction and frequent skipping of glucose measurements that prevented patients from using it as a tool for day-to-day diabetes management. More recently, several new real-time CGM systems have been introduced that have improved accuracy, functionality, and user tolerance.In a multicenter randomized controlled trial, our Juvenile Diabetes Research Foundation (JDRF) Continuous Glucose Monitoring Study Group evaluated the effectiveness of CGM compared with standard blood glucose monitoring in 451 adults and children ≥8 years old with type 1 diabetes, 322 of whom had baseline A1C ≥7.0% and 129 of whom had baseline A1C <7.0% (7). Among subjects with baseline A1C level ≥7.0%, we found that CGM substantially improved A1C levels during 6 months of follow-up without increasing the frequency of hypoglycemia in adults ≥25 years of age. However, the efficacy of this device as a tool to help participants <25 years of age lower their A1C levels was much more limited (8). Among the subjects with baseline A1C <7.0%, we found that the CGM group had a reduction in hypoglycemia on most measures compared with the control group and was able to maintain mean A1C levels at 6.4%, whereas A1C increased in the control group (9). The present analyses were conducted to determine which demographic, clinical, and psychosocial factors were associated with successful CGM use and A1C improvement in the 232 CGM-group subjects.