Effect of Continuous Glucose Monitoring on Glycemic Control in Adolescents and Young Adults With Type 1 Diabetes: A Randomized Clinical Trial

Abstract

Importance: Adolescents and young adults with type 1 diabetes exhibit the worst glycemic control among individuals with type 1 diabetes across the lifespan. Although continuous glucose monitoring (CGM) has been shown to improve glycemic control in adults, its benefit in adolescents and young adults has not been demonstrated.

Objective: To determine the effect of CGM on glycemic control in adolescents and young adults with type 1 diabetes.

Design, setting, and participants: Randomized clinical trial conducted between January 2018 and May 2019 at 14 endocrinology practices in the US including 153 individuals aged 14 to 24 years with type 1 diabetes and screening hemoglobin A1c (HbA1c) of 7.5% to 10.9%.

Interventions: Participants were randomized 1:1 to undergo CGM (CGM group; n = 74) or usual care using a blood glucose meter for glucose monitoring (blood glucose monitoring [BGM] group; n = 79).

Main outcomes and measures: The primary outcome was change in HbA1c from baseline to 26 weeks. There were 20 secondary outcomes, including additional HbA1c outcomes, CGM glucose metrics, and patient-reported outcomes with adjustment for multiple comparisons to control for the false discovery rate.

Results: Among the 153 participants (mean [SD] age, 17 [3] years; 76 [50%] were female; mean [SD] diabetes duration, 9 [5] years), 142 (93%) completed the study. In the CGM group, 68% of participants used CGM at least 5 days per week in month 6. Mean HbA1c was 8.9% at baseline and 8.5% at 26 weeks in the CGM group and 8.9% at both baseline and 26 weeks in the BGM group (adjusted between-group difference, -0.37% [95% CI, -0.66% to -0.08%]; P = .01). Of 20 prespecified secondary outcomes, there were statistically significant differences in 3 of 7 binary HbA1c outcomes, 8 of 9 CGM metrics, and 1 of 4 patient-reported outcomes. The most commonly reported adverse events in the CGM and BGM groups were severe hypoglycemia (3 participants with an event in the CGM group and 2 in the BGM group), hyperglycemia/ketosis (1 participant with an event in CGM group and 4 in the BGM group), and diabetic ketoacidosis (3 participants with an event in the CGM group and 1 in the BGM group).

Conclusions and relevance: Among adolescents and young adults with type 1 diabetes, continuous glucose monitoring compared with standard blood glucose monitoring resulted in a small but statistically significant improvement in glycemic control over 26 weeks. Further research is needed to understand the clinical importance of the findings.

Trial registration: ClinicalTrials.gov Identifier: NCT03263494.

Conflict of interest statement

Conflict of Interest Disclosures: Dr Laffel reported receiving personal fees from NovoNordisk, Eli Lilly, Sanofi, Insulet, Convatec, Dexcom, Medtronic, Roche, Boehringer Ingelheim, and Insulogic outside the submitted work. Dr Beck reported receiving grants and nonfinancial support from Dexcom; consulting fees paid to his institution from Bigfoot BioMedical, Insulet, and Eli Lilly; grants and consulting fees paid to his institution from Tandem Diabetes Care; and nonfinancial support from Roche and Ascencia outside the submitted work. Dr Clements reported receiving personal fees from Glooko, Medtronic, and Eli Lilly outside the submitted work. Dr Criego reported receiving grants from DexCom, Medtronic, Insulet, Juvenile Diabetes Research Foundation, the National Institutes of Health, and Abbott and study supplies from Eli Lilly outside the submitted work. Dr DeSalvo reported receiving personal fees and nonfinancial support from Dexcom. Dr Hood reported receiving grants from Dexcom and personal fees from Lifescan Diabetes Institute outside the submitted work. Dr Liljenquist reported receiving grants and nonfinancial support from Abbott and Medtronic outside the submitted work. Dr Messer reported receiving personal fees from Tandem Diabetes Care, Dexcom, Capillary Biomedical, and Clinical Sensors outside the submitted work. Dr Sherr reported receiving grants and personal fees from Medtronic Diabetes and Insulet and personal fees from Sanofi, Eli Lilly, and Bigfoot Biomedical outside the submitted work. Dr Wadwa reported receiving grants, personal fees, and nonfinancial support from Eli Lilly and Dexcom; grants from Bigfoot Biomedical; personal fees from Medtronic; and grants and nonfinancial support from MannKind Corporation, Nordisk, and Tandem Diabetes Care outside the submitted work. Dr Weinstock reported receiving grants from Insulet Corporation, Tolerion Inc, Eli Lilly, Medtronic, Diasome Pharmaceuticals, Boehringer Ingelheim, Oramed Ltd, and Mylan GmbH and personal fees from Insulogic outside the submitted work. Dr Willi reported serving on a data safety monitoring board for the National Institute of Diabetes and Digestive and Kidney Diseases/National Institutes of Health and serving on an advisory panel for Roche Diagnostics outside the submitted work. No other disclosures were reported.

Figures

Figure 1.. Flow of Participants in a Study of the Effect of Continuous Glucose Monitoring (CGM) vs Standard Blood Glucose Monitoring (BGM) on Glycemic Control in Adolescents and Young Adults With Type 1 Diabetes

Information on patients screened but not enrolled was not collected for this study. One participant in the BGM group and 1 participant in the CGM group were determined to be ineligible following randomization (inadequate hours of data during CGM run-in for the CGM participant and real-time CGM used within 3 months prior for the BGM participant). One participant in the BGM group initiated real-time CGM before completing the 26-week visit and was analyzed as randomized. Missing data for the primary outcome were handled by direct likelihood, which maximizes the likelihood function integrated over possible values of the missing data. All participants had data for at least 1 point and were included in the model.

Figure 2.. Hemoglobin A1c Levels During a Study of the Effect of Continuous Glucose Monitoring on Glycemic Control in Adolescents and Young Adults With Type 1 Diabetes

The top and bottom of the boxes denote the 25th and 75th percentile, the line represents the median, and the dot represents the mean. The whiskers represent the minimum and maximum values after removing outliers.