. Author manuscript; available in PMC: 2021 Dec 7.
Published in final edited form as: JAMA. 2021 Jun 8;325(22):2255–2257. doi: 10.1001/jama.2021.6208
Monica E Peek
1, Celeste C Thomas
2
PMCID: PMC8649865NIHMSID: NIHMS1759242PMID: 34077505
The publisher's version of this article is available at JAMA
See the article "Effect of Continuous Glucose Monitoring on Glycemic Control in Patients With Type 2 Diabetes Treated With Basal Insulin" on page 1.
See the article "Association of Real-time Continuous Glucose Monitoring With Glycemic Control and Acute Metabolic Events Among Patients With Insulin-Treated Diabetes" on page 1.
Persons from racial and ethnic minority populations, those inlow-income groups, and other socially marginalized groups are disproportionatelyaffected by type 2 diabetes and experience higher disease prevalence, poorer glycemiccontrol, higher rates of diabetes complications, and higher prevalence of comorbidconditions.1,2 Achieving glucose targets that will reduce therisk of diabetes complications, particularly among high-risk groups, is critical toimprove the health and well-being of those with diabetes and to reduce health careutilization and expenditures. Yet, diabetes control remains elusive. Self-monitoring ofblood glucose, while still a standard part of diabetes self-management, has not beenshown to result in self-adjustments to insulin in primary care settings. This representsa significant opportunity gap because 30% of patients with type 2 diabetes are treatedwith some form of insulin.3
Real-time continuous glucose monitoring (CGM), which measures glucose levels insubcutaneous interstitial fluid as frequently as every 5 minutes, has been shown toimprove diabetes control, reduce hypoglycemia, and be cost-effective for patients withtype 1 diabetes.4,5 Less research has been conducted among patientswith type 2 diabetes, but clinical trials involving patients using intensive insulinregimens (eg, basal/bolus insulin) have shown reductions in hemoglobin A1c(HbA1c) levels and shorter intervals of hypoglycemia.6,7 Severalquestions remain: Can the results of clinical trials of patients with type 2 diabetes betranslated into usual care settings? Can patients with type 2 diabetes who use lessintensive insulin regimens benefit from CGM? Can CGM be feasibly implemented in primarycare settings, where most of type 2 diabetes management occurs? In this issue ofJAMA, the randomized clinical trial (RCT) reported by Martens etal8 and the observational studyreported by Karter et al9 provide newdata that help provide answers to these questions.
Martens et al8 conducted an RCTof CGM (n = 116) vs blood glucose meter (BGM) monitoring (n = 59) among adults with type2 diabetes who were taking basal insulin without prandial insulin and were recruitedfrom primary care practices. At 8 months, the mean HbA1c level improved from9.1% to 8.0% in the CGM group and from 9.0% to 8.4% in the control group (adjusteddifference, −0.4% [95% CI, −0.8% to −0.1%]). This effect size mayhave been greater if the control group had received usual care rather than instructionson how to self-titrate insulin based on BGM data. Compared with the BGM group, the timein range, or the amount of time spent in the target blood glucose range (70-180 mg/dL),was 3.6 hours per day higher, the mean glucose level was 26 mg/dL lower (95% CI,−41 to −12), and the time with glucose levels greater than 250 mg/dL was3.8 hours per day less in the CGM group (all P < .001). Therewere also high rates of satisfaction among CGM users.
Karter et al9 conducted aretrospective cohort study of 41753 adult patients (36 080 with type 2 diabetes, 5673with type 1 diabetes) who were treated with insulin and were receiving care at KaiserPermanente.9 The authorsfollowed the outcomes of those who initiated CGM (3806 patients) compared with those whodid not; the CGM group primarily used basal/bolus insulin regimens, whereas the controlgroup was treated with various types of insulin. Over the 4-year study period (whichended in December 2018), the authors reported a difference-in-difference reduction inHbA1c level of −0.40% (95% CI, −0.48% to −0.32%) andin rates of emergency department visits and hospitalization for hypoglycemia of 2.7%(95% CI, −4.4% to −1.1%). The net change in HbA1c level wasgreater among patients with type 2 diabetes (−0.56% [95% CI, −0.72% to−0.41%]) than among patients with type 1 diabetes (−0.34% [95% CI,−0.43% to −0.25%]) (P value for interaction = .003). Inaddition, a sensitivity analysis revealed a dose-response association between CGMadherence (0, 1, or ≥2 claims for CGM transmitters) and changes inHbA1c level and hypoglycemia health care utilization.
These studies are important for several reasons. First, they confirm that CGM isa technology that can be effectively used by patients with type 2 diabetes to improveglycemic control. The trial by Martens et al8 recruited a diverse sample of patients who have disproportionatelyhad barriers to fully accessing health care and health care-related technology and alsohave had disproportionately lower rates of adherence to diabetes treatment plans. Mostpatients in this RCT were non-White persons (53%), had less than a college degreeeducation (55%), and did not have private insurance (58%). Exploratory analysessuggested that the reduction in HbA1c level did not differ across age groups,baseline diabetes control, education level, and diabetes numeracy, thus indicating abroad population benefit for CGM among patients with type 2 diabetes. The observationalstudy from Karter et al9 demonstratedthe benefits associated with CGM in usual care settings and found a greater improvementin diabetes control among patients with type 2 diabetes than those with type 1diabetes.
Second, the clinical trial by Martens et al8 demonstrated the promise of using CGM in primary care settings,where most patients with type 2 diabetes receive their care. This trial, in which studyclinicians met with trial participants during in-person clinic visits followed byvirtual visits, provides a model that could be replicated or modified in many primarycare practices throughout the US. For example, having an initial consultation with anendocrinologist followed by telehealth visits with advanced practice nurses in anendocrinology practice could allow for download and interpretation of the CGM data inthe specialty practice without requiring primary care practices to develop thisexpertise. A recent telehealth program that included remote monitoring of CGMdemonstrated statistically significant reductions in HbA1c levels among 594patients with type 2 diabetes.10Project Extension for Community Health Outcomes (ECHO) successfully used remote learningas a venue for subspecialists to train primary care physicians to treat a range ofconditions, including complex diabetes care,11 and could be an alternative strategy for integrating CGM usageinto primary care practice.
Third, these studies suggest that patients with type 2 diabetes who use lessintensive insulin regimens may have similarly robust glycemic benefit as those whorequire more intensive regimens. In both the clinical trial, in which the interventiongroup received basal insulin only, and the observational study, in which 97% of the type2 diabetes CGM group was taking basal/bolus insulin, the difference in HbA1creduction compared with the group that did not initiate CGM was −0.4%. This hassignificant implications for health policy. While patients in the RCT were taking basalinsulin only and monitoring their blood glucose 3 or more times per week, the currentAmerican Diabetes Association grade A guidelines for CGM use include multiple dailyinjections of insulin (or an insulin pump) and Medicare guidelines require 3 or moredaily injections of insulin (or an insulin pump) and self-monitoring of glucose 4 ormore times daily.12,13 The RCT by Martens et al8 demonstrates that CGM is effective in patientswith type 2 diabetes who are treated with less intensive insulin regimens and adds tothe body of evidence that CGM is effective among patients with less intensive bloodglucose monitoring.14 The Medicarecriteria have created significant administrative barriers to CGM use even for patientswho are currently eligible because of the substantial documentation requirements thatare unfamiliar, time-consuming, or both to clinicians and their staff. These criteriaalso create access barriers for patients who could clinically benefit from CGM but arenot currently eligible. It is time to revise the Medicare criteria for CGM to reflectthe current scientific evidence and simultaneously mitigate disparities in CGM accessand diabetes control.13,15
Fourth, the RCT results suggest that patient engagement (ie, improved insulinadherence, changes in diet, or increased physical activity in response to CGM readings)was the most likely source of improved glycemic control because there were nodifferences in the total amount of insulin between study groups or in the amount ofmedication adjustments by clinicians. Activated patients are a powerful part ofachieving diabetes control.16 Patientsin the clinical trial by Martens et al8reported high rates of satisfaction with the CGM, including high mean“benefits” scores and low mean “hassle” scores, suggesting awillingness of this diverse patient population to engage with the technology. Access todiabetes-related technology, including CGM, has been restricted among marginalizedpopulations. These studies add to the literature by demonstrating that persons fromracial and ethnic minority populations, low-income persons, and those with low numeracywant to be engaged, and can successfully be engaged, in diabetes-related technology thatenhances self-management and improves diabetes control.
In summary, the studies by Karter et al9 and Martens et al8 provide additional evidence that patients with type 2 diabetesbenefit from the use of CGM in terms of improved HbA1c level, time spent inthe target blood glucose range, and reduced hypoglycemic episodes. The glycemic benefitsmay be primarily due to patient factors, such as insulin adherence and lifestylemodifications, and provide a powerful narrative that CGM may be a useful technology thathelps control diabetes among multiple patient groups. Important policy changes inMedicare eligibility to CGM for type 2 diabetes and institutional changes that promoteits use in primary care will go a long way to improving diabetes control and reducingcomplications, particularly among the populations most in need. The time has come tobroaden access to CGM for patients with type 2 diabetes.
Footnotes
Conflict of Interest Disclosures: Dr Peek reported being apaid speaker for PRIME Education and giving a talk on continuous glucosemonitoring. Dr Thomas reported no disclosures.
Contributor Information
Monica E. Peek, Section of General Internal Medicine, Chicago Center for Diabetes Translation Research, Center for the Study of Race, Politics, and Culture, University of Chicago, Chicago, Illinois.
Celeste C. Thomas, Section of Endocrinology, Chicago Center for Diabetes Translation Research, University of Chicago, Chicago, Illinois.
REFERENCES
- 1.Centers for Disease Control andPrevention. National Diabetes Statistics Report,2020. Centers for Disease Control and Prevention,US Dept of Health and Human Services;2020. [Google Scholar]
- 2.Spanakis EK, Golden SH. Race/ethnic difference in diabetes and diabeticcomplications. Curr Diab Rep.2013;13(6):814–823.doi: 10.1007/s11892-013-0421-9 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Selvin E, Parrinello CM, Daya N, Bergenstal RM. Trends in insulin use and diabetes control in the US:1988-1994 and 1999-2012. Diabetes Care.2016;39(3):e33–e35.doi: 10.2337/dc15-2229 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Beck RW, Riddlesworth T, Ruedy K, et al. ; DIAMOND Study Group. Effect ofcontinuous glucose monitoring on glycemic control in adults with type 1diabetes using insulin injections: the DIAMOND randomized clinicaltrial. JAMA.2017;317(4):371–378.doi: 10.1001/jama.2016.19975 [DOI] [PubMed] [Google Scholar]
- 5.Wan W, Skandari MR, Minc A, et al. Cost-effectiveness of continuous glucose monitoring for adultswith type 1 diabetes compared with self-monitoring of blood glucose: theDIAMOND randomized trial. Diabetes Care.2018;41(6):1227–1234.doi: 10.2337/dc17-1821 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Dicembrini I, Mannucci E, Monami M, Pala L. Impact of technology on glycaemic control in type 2diabetes: a meta-analysis of randomized trials on continuous glucosemonitoring and continuous subcutaneous insulin infusion.Diabetes Obes Metab.2019;21(12):2619–2625.doi: 10.1111/dom.13845 [DOI] [PubMed] [Google Scholar]
- 7.Ida S, Kaneko R, Murata K. Utility of real-time and retrospective continuousglucose monitoring in patients with type 2 diabetes mellitus: ameta-analysis of randomized controlled trials. JDiabetes Res.2019;2019(4684815):4684815.doi: 10.1155/2019/4684815 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.Martens T, Beck RW, Bailey R, et al. ; MOBILE Study Group. Effect ofcontinuous glucose monitoring on glycemic control in patients with type 2diabetes treated with basal insulin: a randomized clinicaltrial. JAMA. Published onlineJune2, 2021. doi: 10.1001/jama.2021.7444 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9.Karter AJ, Parker MM, Moffet HH, Gilliam LK, Dlott R. Association of real-time continuous glucose monitoringwith glycemic control and acute metabolic events among patients withinsulin-treated diabetes. JAMA. Publishedonline June2, 2021. doi: 10.1001/jama.2021.6530 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Bergenstal RM, Layne JE, Zisser H, et al. Remote application and use of real-time continuous glucosemonitoring by adults with type 2 diabetes in a virtual diabetesclinic. Diabetes Technol Ther.2021;23(2):128–132.doi: 10.1089/dia.2020.0396 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Cuttriss N, Bouchonville MF, Maahs DM, Walker AF. Tele-rounds and case-based training: Project ECHOtelementoring model applied to complex diabetes care.Pediatr Clin North Am.2020;67(4):759–772.doi: 10.1016/j.pcl.2020.04.017 [DOI] [PubMed] [Google Scholar]
- 12.American DiabetesAssociation. 7, Diabetes technology: standards ofmedical care in diabetes–2021. DiabetesCare. 2021;44(suppl1):S85–S99.doi: 10.2337/dc21-S007 [DOI] [PubMed] [Google Scholar]
- 13.Anderson JE, Gavin JR, Kruger DF. Current eligibility requirements for CGM coverage areharmful, costly, and unjustified. Diabetes TechnolTher.2020;22(3):169–173.doi: 10.1089/dia.2019.0303 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 14.Ruedy KJ, Parkin CG, Riddlesworth TD, Graham C; DIAMOND Study Group. Continuous glucosemonitoring in older adults with type 1 and type 2 diabetes using multipledaily injections of insulin: results from the DIAMOND Trial.J Diabetes Sci Technol.2017;11(6):1138–1146.doi: 10.1177/1932296817704445 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 15.Galindo R, Parkin C, Aleppo G, et al. What's wrong with this picture? a critical review ofcurrent CMS coverage criteria for CGM. DiabetesTechnol Ther. 2021. doi: 10.1089/dia.2021.0107 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Peek ME, Harmon SA, Scott SJ, et al. Culturally tailoring patient education and communication skillstraining to empower African-Americans with diabetes.Transl Behav Med.2012;2(3):296–308.doi: 10.1007/s13142-012-0125-8 [DOI] [PMC free article] [PubMed] [Google Scholar]