A systematic review on clinical implication of continuous glucose monitoring in diabetes management

INTRODUCTION Diabetes Mellitus (DM) is one of the most prevalent endocrine disorders worldwide with several short-term and long-term complications including macro- and microvascular disorders.[1] It is estimated that approximately 592 million people will be affected with diabetes mellitus by 2035.[2] The health-disease burden showed increasing trends over the past decade[2] and to improve health-related quality of life, along with diabetic care, extensive monitoring guidelines should also be implemented.[12345] Literature showed dominant prevalence of type 2 diabetes mellitus (T2DM) over type 1 diabetes mellitus (T1DM) all around the world.[14,5] There are several challenges in the management of diabetes mellitus in the health-care system.[6] The effect and management outcomes based on multifactorial concept including demographic variability, disease and social functioning, and self-care behavior are the strong influencers in treatment plan.[45] Disease control or progression based on continuous/frequent blood glucose monitoring[456] will further facilitate the process of rational prescribing.[36] Several studies showed that self-care behavior specific to glucose monitoring plays a vital role in the management of glycemic levels.[23456] The continuous glucose monitoring (CGM) has led to a clinical shift in the management of DM.[7] This technique is based on real-time glycemic monitoring, glucose levels trending alerts, condition-related predictive notifications, and the ability to make care plan on glycemic levels without the use of conventional self-monitoring blood glucose (SMBG).[89] This automated system has helped patients with T1DM with insulin dosing process; however, its success is based on users’ perspectives to wear such device in terms of easiness, comfortability, cost, and potential benefits over SMBG. It is found that consistent use of CGM provides sustained glycated hemoglobin (HbA1c) reduction of 0.5%–1.2%.[789] The clinical implications of CGM and its application in clinical practice are based on the patient-related factors. Several studies have proposed the beneficial outcomes of CGM in the practice but limited to T1DM only. The patients’ and health-care professionals’ perspectives toward the use of device are still undermining. Therefore, this study aimed to evaluate the literature for clinical implication of CGM in different population (i.e., geriatric, adult, and pregnancy) and understand the users’ perspectives on the CGM use compared with standard SMBG and also identify the areas of application to CGM with limited literature. MATERIALS AND METHODS Eligibility criteria Continuous glucose monitoring CGM is the monitoring parameter for patients with DM. SMBG SMBG is also a self-care model for patients with diabetes mellitus but implication and practice are limited to individual behavior. Clinical implications of CGM Studies that focused on CGM-based monitoring among patients with diabetes mellitus and evaluate the clinical outcomes in terms of safety and/or efficacy profile. HbA1c and eA1c These are the predictive markers in the treatment of diabetes mellitus. Studies evaluating glycated hemoglobin values are considered for systematic review. Users perceptions/perspectives Studies evaluating the personnel perception or perspectives toward the use of CGM are also considered in this study. Literature search Articles were searched from different databases and individual journal websites including Google Scholar, ScienceDirect, Sagepub, Libertpub, American Diabetes Association (Diabetes Care), Wiley Online Library, EndocrineWeb, touchENDOCRINOLOGY, PROSPERO, Biomed Central (BMC), Diabetes Technology and Therapeutics, The San Diego Union-Tribune, PubMed(ncbi), Clinical Trials List, SCOPUS, and Elsevier. Search keywords The following were the search keywords: “CGM (continuous glucose monitoring)”, “safety”, “efficacy”, “type 2 DM”, “comorbidities”, “elderly”, “benefits”, “improved”, “glycemic”, and “outcomes” Study selection and data extraction Abstracts and conference proceedings were screened to exclude that do not involve in the following inclusion criteria. The articles should be published between 2017 and 2019. Primary literature would be specific only for T1DM and T2DM. In addition, the literature should also focus on the safety and efficacy of CGM. Also, studies evaluating users (both health-care providers’ and patients’) perspectives were included in the systematic review. Quality assessment Mixed-method appraisal tool (MMAT)[10] checklist is a comprehensive tool for quality assessment of different research design articles in the systematic review. It contains five domains on research design, each with five specific item appraisal questions. The appraisal tool consists of four sub-domains; data collection and recording, methodological design, study population and statistical analysis in-between groups.[10] RESULTS AND DISCUSSION General data This systematic review looks into 17 articles that were taken from 2017 to 2019. Five (29%) studies were from the USA, three (17%) studies were from the UK, one from South America, one from Japan, one from India, one from France, one from Italy, one from Belgium, one from Germany, one from Slovenia, and one from Georgia [Supplementary Table 1]. The quality was assessed using MMAT guidelines, according to which 11 (64%) studies were low-risk and 6 (35%) were mid-risk studies [Figure 1].Supplementary Table 1: Systematic review of studies included in the studyFigure 1: Preferred reporting items for systematic reviews and Meta-analyses (PRISMA) diagram of systematic reviewClinical themes In this systematic review, some of the things discussed are the discrepancy between calculated estimated A1c (eA1c) and HBA1c, how CGM is user friendly and is less time-consuming than conventional methods for blood glucose monitoring, and how pregnant women with diabetes mellitus also benefit from CGM [Table 1].Table 1: Content and subtheme analysis of systematic reviewThe review addresses “Clinical relevance of HBA1c in monitoring,” “Clinical controversies of HB1Ac,” “CGM used in TD1 than TD2,” “Limitations of CGM in clinical practice,” “Patient and HCPs perception on CGM,” “Future implications of CGM,” and “Glucose variability” [Figure 2].Figure 2: Systematic review blueprintClinical relevance of glycated hemoglobin HbA1c is the classic method for assessing the glucose levels.[111213] Most organizations that have been assessing glucose levels using this method have set a recommended target of 7.0% (53 mmol/mol) for adults and 7.5% (58 mmol/mol) for children; however, some other organizations suggest a different target value for HbA1c such as 6.5% for adults as well as for children.[12] Nonetheless, all the organizations agree that HbA1c limit should be set person to person rather than a generalized limit.[13] Considering the importance of HBA1c value and the increased use of CGM has introduced a new term eA1c, which is supposed to be an equivalent to HBA1c (laboratory generated); it uses the mean glucose data from CGM or SBGM to produce a value. However, due to lack of agreement between the lab A1C and eA1c, U.S. Food and Drug Administration (US FDA) suggested changing the nomenclature of eA1c to Glucose Management Indicator (GMI) and also derived a formula to convert the CGM readings of mean blood glucose to GMI.[14] The formula that is used to calculate the GMI is derived from a regression line by plotting a graph of “mean glucose concentration” on the x-axis and “simultaneously measured A1C” on y-axis. The very first study to generate eA1c value was A1c-derived average glucose study conducted in 2006–2007.[14] A more recent study by Beck et al.[14] generated an equation which was validated later by HypoDE study. The equation was GMI (%) = 3.31+0.02392x (mean glucose in mg/dL). Real-time continuous glucose monitoring (RT-CGM) was carried out, in which patients received various therapies that involved diet, lifestyle, and different combinations of antihyperglycemic therapies including basal insulin therapy.[26] As the trial proceeded, HbA1c reduction was observed despite of the lower doses given to the patients. RT-CGM study was considered as it will avoid the energy burnout of T2DM people, hence less chances of error in the results, even to those people who use insulin and along all this HbA1c reduction is observed.[26] Major changes are seen in those whose HbA1c values were high at baseline.[26] However, when this study was carried out on a mixed T1DM and T2DM, there were no significant results for HbA1c.[26] Another study was run on a sample of population consisting of 50 units. These units were 50 pregnant females who were divided into two groups, 25 females in each group where CGM, SMBG, and capillary blood glucose were observed in order to check how these variables affect and how much they affect the HbA1c concentration. These females were kept under study from the beginning of their pregnancy and also, they were to take their values three times a week and the results recorded are shown in Figure 3.[19]Figure 3: Continuous glucose monitoring (CGM) implication in pregnant women vs. self-monitoring of blood glucose (SBGM) for adverse drug reaction. As shown in the above the graph, the increase in Hb1Ac level in Group 1 (CGM and SMBG) is almost insignificant, whereas in Group 2 (control group) the increase in Hb1Ac level is approximately 0.5%Clinical controversies of glycated hemoglobin The conventional method for evaluating glycemic control has been the measurement of HbA1c. Although this method is still being used, there are several drawbacks of using it. Intra- and interday glycemic excursions are not considered[13] that give rise to acute events such as hypoglycemia and postprandial hyperglycemia, which remains undetected on a daily basis. Moreover, it is an erratic measure in the case of anemic patients,[13] iron deficiency,[13] hemoglobinopathies,[13] and preg

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   Patients’ and caregivers’ experiences of using continuous glucose monitoring to support diabetes self-management: qualitative study · 2018

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