Effect of Continuous Glucose Monitoring on Glycemic Control in Patients With Type 2 Diabetes Treated With Basal Insulin
Authors: Thomas Martens, Roy W. Beck, Ryan Bailey, Katrina J. Ruedy, Peter Calhoun, Anne L. Peters, Rodica Pop-Busui, Athena Philis-Tsimikas, Shichun Bao, Guillermo Umpierrez, Georgia Davis, Davida Kruger, Anuj Bhargava, Laura Young, Janet B. McGill, Grazia Aleppo, Quang T. Nguyen, Ian Orozco, William Biggs, K. Jean Lucas, William H. Polonsky, John B. Buse, David Price, Richard M. Bergenstal, Anders Carlson, Sharon Chambers, Shoua Yang, Marian Sue Kirkman, Alexander Kass, Rachael Fraser, Terra Cushman, Clementina Ramos, Maria Magar, Martha Walker, Sara Serafin-Dokhan, Maamoun Salam, Stacy Hurst, Mary Jane Clifton, Jelena Kravarusic, Anupam Bansal, Candice Fulkerson, Lynn Ang, Caroline Richardson, Kara Mizokami-Stout, Jake Reiss, Virginia Leone, Kirstie Stifel, George Dailey, Amy Change, James McCallum, Maria Isabel Garcia, Dianne Davis, Cynthia Lovell, Connie Root, Freida Toler, Lori Wilhelm, Robin Eifert, Lorena Murguia, Becky Cota, Loida Nguyen, Randie Lipski, Mary Katherine Lawrence, Adelle Fournier, Matthew Carter, Stephanie Hoover, Nathan Cohen, Thomas Mouse, Jessica Rusnak, Tiffany Campos, Nelly Njeru, Tom Arant, Stayce E. Beck, Andrew Balo
Journal: JAMA (2021)

<h3>Importance</h3> Continuous glucose monitoring (CGM) has been shown to be beneficial for adults with type 2 diabetes using intensive insulin therapy, but its use in type 2 diabetes treated with basal insulin without prandial insulin has not been well studied. <h3>Objective</h3> To determine the effectiveness of CGM in adults with type 2 diabetes treated with basal insulin without prandial insulin in primary care practices. <h3>Design, Setting, and Participants</h3> This randomized clinical trial was conducted at 15 centers in the US (enrollment from July 30, 2018, to October 30, 2019; follow-up completed July 7, 2020) and included adults with type 2 diabetes receiving their diabetes care from a primary care clinician and treated with 1 or 2 daily injections of long- or intermediate-acting basal insulin without prandial insulin, with or without noninsulin glucose-lowering medications. <h3>Interventions</h3> Random assignment 2:1 to CGM (n = 116) or traditional blood glucose meter (BGM) monitoring (n = 59). <h3>Main Outcomes and Measures</h3> The primary outcome was hemoglobin A<sub>1c</sub>(HbA<sub>1c</sub>) level at 8 months. Key secondary outcomes were CGM-measured time in target glucose range of 70 to 180 mg/dL, time with glucose level at greater than 250 mg/dL, and mean glucose level at 8 months. <h3>Results</h3> Among 175 randomized participants (mean [SD] age, 57 [9] years; 88 women [50%]; 92 racial/ethnic minority individuals [53%]; mean [SD] baseline HbA<sub>1c</sub>level, 9.1% [0.9%]), 165 (94%) completed the trial. Mean HbA<sub>1c</sub>level decreased from 9.1% at baseline to 8.0% at 8 months in the CGM group and from 9.0% to 8.4% in the BGM group (adjusted difference, −0.4% [95% CI, −0.8% to −0.1%];<i>P</i> = .02). In the CGM group, compared with the BGM group, the mean percentage of CGM-measured time in the target glucose range of 70 to 180 mg/dL was 59% vs 43% (adjusted difference, 15% [95% CI, 8% to 23%];<i>P</i> &lt; .001), the mean percentage of time at greater than 250 mg/dL was 11% vs 27% (adjusted difference, −16% [95% CI, −21% to −11%];<i>P</i> &lt; .001), and the means of the mean glucose values were 179 mg/dL vs 206 mg/dL (adjusted difference, −26 mg/dL [95% CI, −41 to −12];<i>P</i> &lt; .001). Severe hypoglycemic events occurred in 1 participant (1%) in the CGM group and in 1 (2%) in the BGM group. <h3>Conclusions and Relevance</h3> Among adults with poorly controlled type 2 diabetes treated with basal insulin without prandial insulin, continuous glucose monitoring, as compared with blood glucose meter monitoring, resulted in significantly lower HbA<sub>1c</sub>levels at 8 months. <h3>Trial Registration</h3> ClinicalTrials.gov Identifier:NCT03566693