Real-Time CGM Use Reduces HbA1c, Outpatient Visits in Patients with Type 1 and Type 2 Diabetes

Andrew Karter, PhD

A retrospective cohort study of more than 41,000 insulin-treated patients with diabetes suggests patients with type 1 and type 2 diabetes could benefit from the initiation of real-time continuous glucose monitoring (CGM).

Results of the study indicate use of CGM in patients with diabetes resulted in significant improvements in HbA1c and reductions in emergency department visits and hospitalizations for hypoglycemia, but no significant changes in emergency department visits or hospitalizations for hyperglycemia or for any reason.

"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, in a statement.

With an interest in describing the clinical outcomes associated with CGM initiation in patients with diabetes, Karter and colleagues from the Permanente Medical Group designed a retrospective cohort study to compare use and nonuse in patients with type 1 and type 2 diabetes receiving care at Kaiser Permanente Northern California from 2015-2018. In total, 41,753 patients, including 5673 with type 1 diabetes and 36,080 with type 2 diabetes, were identified for inclusion.

Major eligibility criteria for the study included maintaining continuous health plan membership for 12 months before and after baseline, having pharmacy benefits during the 12 months before baseline, having at least 1 pharmacy dispensing of glucose monitoring test strips during the 12 months before baseline, having at least 1 pharmacy dispensing of insulin during the 6 months before baseline, not using CGM between January 1, 2014, and baseline. A total of 10 endpoints were used as outcomes of interest in the trial and were measured during the 12 months before and 12 months after baseline.

Of the 41,753 patients included in the study, 3806 initiated real-time CGM and 37,947 patients were considered noninitiators. Among the 3806 who initiated real-time CGM use, 3462 had type 1 diabetes and 344 had type 2 diabetes. Among the 37,947 non initiators, 2211 had type 1 diabetes and 35,736 had type 2 diabetes.

Compared to noninitiators, those who initiated real-time CGM had similar mean HbA1c, higher rates of hypoglycemia and hyperglycemia, higher predicted risk of hypoglycemia, and were more likely to have been dispensed glucagon, insulin pen or pump, and long- or rapid-acting insulin. Of note, all patients with type 1 diabetes and 97% with type 2 diabetes were using basal-bolus insulin.

Upon analysis, investigates found mean HbA1c declined from 8.17% to 7.76% among real-time CGM initiators and from 8.28% to 8.19% among noninitiators (adjusted difference-in-differences estimate, -0.40%; 95% CI, -0.48 to -0.32%; P <.001). Additionally, rates of hypoglycemia declined from 5.1% to 3.0% among CGM initiators and increased from 1.9% to 2.3% among noninitiators (difference-in-differences estimate, -2.7%; 95% CI, -4.4 to -1.1%; P=.001).

Investigators noted statistically significant differences in adjusted net changes in the proportion of patients with an HbA1c lower than 7% (adjusted difference-in-differences estimate, 9.6%; 95% CI, 7.1% to 12.2%; P <.001), lower than 8% (adjusted difference-in-differences estimate, 13.1%; 95% CI, 10.2 to 16.1%; P <.001), and higher than 9% (adjusted difference-in-differences estimate, -7.1%; 95% CI, -9.5 to -4.6%; P <.001). Investigators also pointed out a statistically significant difference in the number of outpatient visits (adjusted difference-indifferences estimate, -0.4; 95% CI, -0.6 to -0.2; P <.001) and telephone visits (adjusted difference-in-differences estimate, 1.1; 95% CI, 0.8 to 1.4; P <.001), but no significant difference was observed in regard to rates of hyperglycemia, emergency department visits for any reason, or hospitalizations for any reason.

"We now need to determine whether there are other patients who might also benefit, even if they don't meet all of the Medicare criteria. The newest technology isn't always better for everybody. We need to identify the people who are most likely to benefit,” added Richard Dlott, MD, an endocrinologist and the medical director of population care for The Permanente Medical Group, in the aforementioned statement.

This study, “Association of Real-time Continuous Glucose Monitoring With Glycemic Control and Acute Metabolic Events Among Patients With Insulin-Treated Diabetes,” was published in JAMA.