Before the study, 107 (61.1%) patients were taking oral or noninsulin DM medication only, 4 (2.3%) were on insulin only, and 64 (36.6%) were prescribed both insulin and oral/noninsulin antihyperglycemics. Noninsulin and oral antihyperglycemic regimens included combinations of biguanide, dipeptidyl peptidase- 4 inhibitor, sodium-glucose cotransporter-2 inhibitor, sulfonylurea, meglitinide, β-glucosidase inhibitor, glucagon-like peptide-1 (GLP-1) analog, and thiazolidinedione drug classes. Nearly 70% (122) had no reported changes in DM treatment beyond dosage titrations. Among these patients, 18 (10.3%) were on an insulin pump for the duration of the study. Among the 53 (30.3%) patients who had changes in treatment, 31 (17.7%) transitioned from insulin injections to an insulin pump, 13 (7.4%) changed from 1 insulin injection to another (ie, addition of long-acting insulin, transition to u500 insulin, changing from 1 insulin category or brand to another), 8 (4.6%) began an oral/noninsulin antihyperglycemic, 4 (2.3%) began insulin injections, 13 (7.4%) discontinued noninsulin or oral antihyperglycemics, and 2 (1.1%) discontinued insulin during the study period.
Data showed that 113 (64.5%) patients had no changes in antihypertensives. The remaining 62 (35.4%) had the following adjustments: 14 (8%) increased dose of current medication(s), 9 (5.1%) decreased dose of current medication(s), 8 (4.6%) discontinued all antihypertensive medications, 10 (5.7%) switched to a different antihypertensive class, and 16 (9.1%) added additional antihypertensive medication(s) to their existing regimen during the study period.
Patients in the study group used 7 different types of CGM sensors. Chart review revealed that 84 (47.7%) patients used Medtronic devices, with 26 (14.8%) using first-generation Guardian sensors, 50 (28.4%) using Enlite sensors, and 8 (4.5) using Guardian 3 sensors. We found that 81 (46.0%) veterans were prescribed Dexcom devices, with 5 (2.8%) using SEVEN PLUS sensors, 68 (38.6%) using G4-5 sensors, and 8 (4.5%) using G6 sensors. The remaining 10 (5.7%) patients were using Freestyle Libre sensors during the study period.
Discussion
CGM did not correspond with clinically significant reductions in HbA1c. However, veterans with increased health care engagement were likely to achieve clinically significant HbA1c improvements. The veterans in the adherent subgroup had a higher baseline HbA1c, which could be because of a variety of factors mentioned in patient care notes, including insulin resistance, poor dietary habits, and exercise regimen nonadherence. These patients might have had more room to improve their glycemic control without concern of hypoglycemia, and their higher baseline HbA1c could have provided increased motivation for improving their health during the study period.
Adherent patients also had a greater reduction in weight and hospital or clinic visits with CGM compared with the total population. These veterans’ increased involvement in their health care might have led to better dietary and exercise adherence, which would have decreased insulin dosing and contributed to weight loss. Only 1 patient in the adherent subgroup initiated a GLP-1 agonist during the study period, making it unlikely that medication changes had a significant impact on weight loss in the subgroup analysis. This improvement in overall health status might have contributed to the reduction in hospital or clinic visits observed in this population.
Average systolic BP data decreased minimally in the total survey population and increased in the adherent subgroup over the course of the study. These results were determined to be statistically significant. Changes in systolic BP readings were minimal, indicating that it is unlikely that these changes contributed meaningfully to the patients’ overall health status.
Although not related to the study objectives, the adherent population required less antihypertensive adjustments with similar BP control. This could be explained by improved overall health or better adherence and engagement in therapy. The results of this project show that despite limited medication changes, T2DM management improved among adherent patients using CGM. The general study population, which was more likely to have documented nonadherence with treatment or clinic appointments, had minimal benefit. CGM technology in the T2DM veteran population is more likely to have significant clinical benefit in patients who are adherent with their medication regimens and follow-up appointments compared with the larger study population.
The results of this study are in line with previous studies on CGM use in the T2DM patient population. We agree with the previously published research that CGM alone does not have a meaningful impact on HbA1c reduction. Our study population also was older than those in previous studies, adding to the Haak and colleagues conclusion that patients aged < 65 years might have better outcomes with CGM.4