Real Time CGM Improves A1c, Time in Range in T2D Patients on Less Intensive Treatment

Greatest improvements in A1c, %TIR, and other glycemic parameters were seen in patients treated with ≤1 medication, in another challenge to current payer restrictions.

Real time continuous glucose monitoring (rtCGM) was associated with signficant improvements in glycemic control in patients with type 2 diabetes (T2D) treated with basal insulin alone or with noninsulin therapies, according to study results recently published in Diabetes Technology & Therapeutics.

While significant reductions in mean hemoglobin A1c (A1c) were achieved regardless of baseline treatment (ie, ≤1 vs ≥2 medications), the greatest improvements in % time in range (%TIR) and % time above range (%TAR) without risk of increased hypoglycemia were seen in study participants treated with ≤1 agent, insulin or noninsulin.

Coauthors of the study, Thomas Grace, MD, and Jay Salyer, APRN-CNP, both of Endocrinology & Diabetes Specialists of Northwest Ohio, state that their findings are consistent with those of similar studies on use of rtCGM for T2D patients treated with less intensive antihyperglycemic regimens and “call into question the relevancy of current rtCGM eligibility criteria that deny insurance coverage to this T2D population.”

Current payer eligibility requirements for rtGGM, according to the study, are daily treatment with ≥3 insulin injections (or pump) and history of blood glucose monitoring 4 times/day. Grace and Salyer write that they designed the current study to investigate the relevance of these criteria to successful use of rtCGM.

The prospective, open-label, interventional single-arm study assessed clinical effects of use of rtCGM use over a period of 6 months in patients with T2D treated with basal insulin alone or with noninsulin therapies. Primary outcomes were changes in A1c, average glucose, glycemic variability, and %TIR, %TAR, and % time below range (%TBR). Changes in body weight and body mass index (BMI) were secondary outcomes of interest.

Patient requirements for study inclusion were a diagnosis of T2D, A1c >7.5% (>58 mmol/mol), and treatment with basal insulin, noninsulin injectable antidiabetic medication, oral antidiabetic medication, and/or diet and exercise. Patients were excluded if they had a diagnosis of type 1 diabetes, an A1c ≤7.5% (≤58 mmol/mol) or were being treated with prandial or premix insulin.

Patient visits were scheduled for initial screening and baseline measures, then clinic visits at 3 and 6 months. Demographic information, biometric measurements, medical and medication history were obtained at the screening visit and blood was drawn for baseline A1c levels.

Each patient was given a rtCGM device (Dexcom G6; Dexcom, Inc., San Diego, CA) and comprehensive training in its use and interpreting device data. All settings were individualized for each patient.

rtCGM data were downloaded and reviewed by patients and investigators at the 3- and 6- month visits. Treatment changes were made in response to problematic glycemic parameters; blood samples and biometric measures were documented.

For all rtCGM metrics, data from the first month of rtCGM use were utilized as surrogate baseline for assessment of changes.


Of the original 43 patients enrolled, 38 had full data available for the final analyses. Average age of the cohort was 55 years, 47% were women, and the majority (97%) were White. Mean weight was 103.5 kg, BMI, 35.6, and average duration of diabetes was ~14 years. Prior to study enrollment, all patients were performing SMBG <3 time/day. Most were treated with metformin (55%) and/or a second agent, ie, basal insulin (42%), a sulfonylurea (39%), DPP-4 inhibitor (32%), GLP-1 agonist (24%), thiazolidinedione (13%), SGLT-2 inhibitor (5%).

Therapy was intensified for 20 of the 38 patients over the 6-month study period and was changed or reduced for 15. There were no severe hypoglycemic events or device-related adverse events reported during the study.

At 6 months, Grace and Salyer report, they saw significant reductions in A1c (Δ-3.0% ± 1.3%, P <.001) with reductions similar in participants treated with ≤1 medication and those treated with ≥2 medications. Reductions in average glucose level, similarly, were significant (Δ -23.6 ± 38.8, P <.001).

From baseline to month 6, across all therapy groups, %TIR increased (15.2 ± 22.3, P< .001) with corresponding reductions in %TAR (−14.9 ± 22.9, P<.001). Moreover, all participants maintained %TBR targets (<4% at 70 mg/dL, <1% at <54 mg/dL). There were no changes observed in glycemic variability.

The greatest improvements in %TIR (17.6 – 16.3, P=0.002) and %TAR (-17.0 – 16.9 0.005) were seen in patients treated with ≤1 medication, insulin or noninsulin.

The researchers also observed significant reductions from baseline to 6 months in body weight (Δ −3.1 ± 6.4 kg, P = 0.002) and BMI Δ −1.1 ± 2.3, P = 0.002).

Grace and Salyer point out a key strength of the study was “the ability to generate evidence of the effectiveness and feasibility of rtCGM use in a real-world, clinical practice setting in patients who are similar to those encountered in clinical practice.” They note, too, several limitations to generalizing their results including the homogeneity of the population, the diversity of baseline A1c and therapy, and the short duration of the study.

They conclude: “Current eligibility criteria established by government and commercial health plans are medically unfounded and deny coverage for the majority of T2D patients who could potentially improve their glycemic control through rtCGM use.”

Reference: Grace T, Salyer J. Use of real time continuous glucose monitoring improves glycemic control and other clinical outcomes in type 2 diabetes patients treated with less intensive therapy. Diabetes Technol Ther. 2022; 24. Published online January 5, 2022.