Continuous Glucose Monitoring vs Blood Glucose Meter Monitoring in Type 2 Diabetes

CGM, diabetes
Close-up of young Caucasian woman with type 1 diabetes holding smart phone to swipe sensor on her arm for glucose concentration data.
Researchers studied the effectiveness of continuous glucose monitoring in adults with type 2 diabetes treated with basal insulin without prandial insulin in primary care practices.

Continuous glucose monitoring (CGM) was associated with better glycemic control than blood glucose meter (BGM) monitoring, according to results of a randomized clinical trial that were published in JAMA.

Adults (N=175) with type 2 diabetes who had poor glycemic control were recruited at 15 centers in the United States from July 30, 2018, to October 30, 2019. Prior to randomization, participants used a CGM device that recorded glucose trends for up to 10 days.

Participants were randomly assigned in a 2:1 ratio to continue using the CGM or to switch to a BGM. The CGM group used a Dexcom G6 CGM System that assessed blood glucose every 5 minutes, and the BGM group was instructed to test fasting and postprandial glucose 1 to 3 times daily.

Patients in the CGM and BGM cohorts had a mean age of 56 (SD, 9) and 59 (SD, 9) years, 53% and 46% were women, 43% and 56% were White, they had been diagnosed with diabetes 14 (SD, 9) and 15 (SD, 10) years previously, and hemoglobin A1c (HbA1c) at baseline was 9.2% (SD, 1.0%) and 9.0% (SD, 0.9%), respectively.

At 8 months, HbA1c had decreased to 8.0% (SD, 1.4%) in the CGM and 8.4% (SD, 1.3%) in the BGM cohorts (P =.02).

The CGM cohort was associated with increased time in the 70 to 180 mg/dL glucose range (risk-adjusted difference [RAD], 15%; 8% to 23%; P <.001), decreased time in the >250 mg/dL glucose range (RAD, -16%; 95% CI, -21% to -11%; P <.001), decreased mean glucose (RAD, -26 mg/dL; 95% CI, -41 to -12 mg/dL; P <.001), and decreased time in the <54 mg/dL glucose range (RAD, -0.10%; 95% CI, -0.15% to -0.04%; P =.001).

Using CGM did not lead to a decreased use of diabetes medications or a lower total daily insulin dose.

At least 1 adverse event was reported by 26% and 20% of the participants in the CGM and BGM cohorts, respectively. Serious adverse events were reported by 9% of each group, severe hypoglycemic events by 1 participant in each group, and 1 diabetic ketoacidosis event by a participant in the CGM cohort.

This study may have been limited by the fact that some of the 8-month follow-up visits were performed virtually due to the COVID-19 pandemic.

These data indicated that patients with type 2 diabetes who had poor glycemic control may have achieved more stable blood glucose concentrations by using a CGM system.

Disclosure: This research was supported by Dexcom Inc. Please see the original reference for a full list of disclosures.


Martens T, Beck RW, Bailey R, et al; MOBILE Study Group. Effect of continuous glucose monitoring on glycemic control in patients with type 2 diabetes treated with basal insulin: a randomized clinical trial. JAMA. 2021;325(22):2262-2272. doi:10.1001/jama.2021.7444