Patient-Oriented Evidence That Matters
Continuous Glucose Monitoring Adds Little Benefit, Especially in Adults
Am Fam Physician. 2021 Jun 1;103(11):697.
Do continuous glucose monitoring devices improve glucose control?
Only patients using intensive insulin therapy who are unsure of when they are extremely hypoglycemic or hyperglycemic should use continuous glucose monitoring. In patients who have diabetes mellitus who are treated with intensive insulin regimens, continuous glucose monitoring modestly decreases A1C in short-term, unmasked studies. The effect goes away when pregnant women and children are excluded from the analysis. Patients with type 2 diabetes made up only 19% of the total number of patients and were not analyzed separately. This meta-analysis had many reasons for not combining the results of the 15 studies—differences in patient demographics, high risk of bias, and extreme heterogeneity of results across the studies. (Level of Evidence = 1a−)
The authors searched four databases, including a trial registry and the Cochrane Registry, to identify 15 randomized trials that enrolled a total of 2,461 patients and followed up for three to nine months. Only three of the included studies comprised patients with type 2 diabetes, all of whom were treated with multiple daily doses of insulin; they accounted for only 19% of the total number of patients. Two researchers decided on study eligibility and extracted the data independently. There was very high heterogeneity among the patient characteristics across the studies. Ages ranged from 11.4 to 67 years, patients had type 1 or type 2 diabetes, and pregnant women were enrolled. There was very high heterogeneity (I2 greater than 90%) for most outcomes. The risk of bias was high for all of the studies because patients and the outcome assessors were aware of whether patients had continuous glucose monitoring. On average (with great variability), A1C decreased by 0.17% (which may translate into approximately 0.5 percentage points) with continuous glucose monitoring, but this difference went away when children and pregnant women
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