Importance: The majority of individuals with type 1 diabetes do not meet recommended glycemic targets.
Objective: To evaluate the effects of continuous glucose monitoring in adults with type 1 diabetes treated with multiple daily insulin injections.
Design, setting, and participants: Open-label crossover randomized clinical trial conducted in 15 diabetes outpatient clinics in Sweden between February 24, 2014, and June 1, 2016 that included 161 individuals with type 1 diabetes and hemoglobin A1c (HbA1c) of at least 7.5% (58 mmol/mol) treated with multiple daily insulin injections.
Interventions: Participants were randomized to receive treatment using a continuous glucose monitoring system or conventional treatment for 26 weeks, separated by a washout period of 17 weeks.
Main outcomes and measures: Difference in HbA1c between weeks 26 and 69 for the 2 treatments. Adverse events including severe hypoglycemia were also studied.
Results: Among 161 randomized participants, mean age was 43.7 years, 45.3% were women, and mean HbA1c was 8.6% (70 mmol/mol). A total of 142 participants had follow-up data in both treatment periods. Mean HbA1c was 7.92% (63 mmol/mol) during continuous glucose monitoring use and 8.35% (68 mmol/mol) during conventional treatment (mean difference, -0.43% [95% CI, -0.57% to -0.29%] or -4.7 [-6.3 to -3.1 mmol/mol]; P < .001). Of 19 secondary end points comprising psychosocial and various glycemic measures, 6 met the hierarchical testing criteria of statistical significance, favoring continuous glucose monitoring compared with conventional treatment. Five patients in the conventional treatment group and 1 patient in the continuous glucose monitoring group had severe hypoglycemia. During washout when patients used conventional therapy, 7 patients had severe hypoglycemia.
Conclusions and relevance: Among patients with inadequately controlled type 1 diabetes treated with multiple daily insulin injections, the use of continuous glucose monitoring compared with conventional treatment for 26 weeks resulted in lower HbA1c. Further research is needed to assess clinical outcomes and longer-term adverse effects.
Trial registration: clinicaltrials.gov Identifier: NCT02092051.