The study in JAMA notes that CGM is now standard of care for patients with type 1 diabetes because of better glucose control.
“The improvement in blood sugar control was comparable to what a patient might experience after starting a new diabetes medication,” said the study’s lead author Andrew J. Karter, PhD, a senior research scientist with the Kaiser Permanente Northern California Division of Research.
Dr. Karter and colleagues sought to estimate clinical outcomes of real-time CGM initiation. To do so, the study team used an exploratory retrospective cohort study to determine changes in outcomes associated with real-time CGM initiation.
Included in the study were 41,753 participants with insulin-treated diabetes; 5,673 diagnosed with type 1 diabetes and 36,080 diagnosed with type 2. Patients received care from a Northern California integrated healthcare delivery system between 2014 and 2019. All had no prior CGM use and self-monitored their blood glucose levels.
The authors note that 3,806 patients—mean age, 42.4 years; 51% female; 91% type 1, 9% type 2—initiated real-time CGM, while 37, 947 patients—mean age, 63.4 years; 49% female; 6% type 1, 94% type 2—did not. The prebaseline mean HbA1c was lower among real-time CGM initiators than among noninitiators, but real-time CGM initiators had higher prebaseline rates of hypoglycemia and hyperglycemia,” the researchers explain.
The study team looked at a range of endpoints measured during the 12 months before and 12 months after baseline:
• Hemoglobin A1c (HbA1c)
• Hypoglycemia (emergency department or hospital utilization)
• Hyperglycemia (emergency department or hospital utilization)
• HbA1c levels lower than 7%, lower than 8%, and higher than 9%
• Emergency department encounter or more for any reason
• Hospitalization or more for any reason
• Number of outpatient visits and telephone visits
Results indicate that mean HbA1c declined among real-time CGM initiators from 8.17% to 7.76%, while dropping 8.28% to 8.19% among noninitiators (adjusted difference-in-differences estimate, −0.40%; 95% CI, −0.48% - −0.32%; P <.001).
In addition, hypoglycemia rates declined among real-time CGM initiators from 5.1% to 3.0%, although it increased among noninitiators from 1.9% to 2.3% (difference-in-differences estimate, −2.7%; 95% CI, −4.4% - −1.1%; P = .001).
No statistically significant differences in the adjusted net changes in the proportion of patients with HbA1c lower than 7% (adjusted difference-in-differences estimate, 9.6%; 95% CI, 7.1%-12.2%; P <.001), lower than 8% (adjusted difference-in-differences estimate, 13.1%; 95% CI, 10.2%-16.1%; P <.001), and higher than 9% (adjusted difference-in-differences estimate, −7.1%; 95% CI, −9.5% - −4.6%; P < .001) were determined. Nor were there significant variations in the number of outpatient visits (adjusted difference-in-differences estimate, −0.4; 95% CI, −0.6 - −0.2; P <.001) and telephone visits (adjusted difference-in-differences estimate, 1.1; 95% CI, 0.8-1.4; P <.001), the authors point out.
“Initiation of real-time CGM was not associated with statistically significant changes in rates of hyperglycemia, emergency department visits for any reason, or hospitalizations for any reason,” the study adds.
On the other hand, researchers advise that “insulin-treated patients with diabetes selected by physicians for real-time continuous glucose monitoring compared with noninitiators had significant improvements in hemoglobin A1c and reductions in emergency department visits and hospitalizations for hypoglycemia.”
Reducing hypoglycemia is important because it is linked with risk for falls, cardiovascular disease, dementia, and death, the authors note.
“Blood sugar levels that go too low can be dangerous,” said senior author Richard Dlott, MD, an endocrinologist and the medical director of population care for The Permanente Medical Group. “This study shows that continuous glucose monitors helped people stay close to their glucose targets without going too low.”
To qualify now for CGM under Medicare guidelines, a patient generally must give themselves three or more shots of insulin daily or use an insulin pump, perform blood glucose testing four or more times a day, and consistently communicate with a diabetes team every 3 to 6 months.
“Selective prescribing of continuous glucose monitors may partially explain the benefits we saw in these patients with type 2 diabetes,” explained Dr. Karter, who is also the associate director for the Health Delivery Systems Center for Diabetes Translational Research, sponsored by the National Institute of Diabetes and Digestive and Kidney Diseases. “Doctors appeared to have preferentially prescribed monitors to patients with a history of hypoglycemia or at high risk of hypoglycemia.”
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