Multicentre, randomised, controlled study of the impact of continuous sub-cutaneous glucose monitoring (GlucoDay) on glycaemic control in type 1 and type 2 diabetes patients

Real time continuous glucose monitoring in high-risk people with insulin-requiring type 2 diabetes: A randomised controlled trial

AIMS

To investigate the impact of real-time continuous glucose monitoring (rtCGM) on glycaemia in a predominantly indigenous (Māori) population of adults with insulin-requiring type 2 diabetes (T2D) in New Zealand.

METHODS

Twelve-week, multicentre randomised controlled trial (RCT) of adults with T2D using ≥0.2 units/kg/day of insulin and elevated glycated haemoglobin (HbA1c) ≥64 mmol/mol (8.0%). Following a 2-week blinded CGM run-in phase, participants were randomised to rtCGM or control (self-monitoring blood glucose [SMBG]). The primary outcome was time in the target glucose range (3.9-10 mmol/L; TIR) during weeks 10-12, with data collected by blinded rtCGM in the control group.

RESULTS

Sixty-seven participants entered the RCT phase (54% Māori, 57% female), median age 53 (range 16-70 years), HbA1c 85 (IQR 74, 94) mmol/mol (9.9 [IQR 8.9, 10.8]%), body mass index (36.7 ± 7.7 kg/m2). Mean (±SD) TIR increased from 37 (24)% to 53 (24)% [Δ 13%; 95% CI 4.2 to 22; P = 0.007] in the rtCGM group but did not change in the SMBG group [45 (21)% to 45 (25)%, Δ 2.5%, 95% CI -6.1 to 11, P = 0.84]. Baseline-adjusted between-group difference in TIR was 10.4% [95% CI -0.9 to 21.7; P = 0.070]. Mean HbA1c (±SD) decreased in both groups from 85 (18) mmol/mol (10.0 [1.7]%) to 64 (16) mmol/mol (8.0 [1.4]%) in the rtCGM arm and from 81 (12) mmol/mol (9.6 [1.1]%) to 65 (13) mmol/mol (8.1 [1.2]%) in the SMBG arm (P < 0.001 for both). There were no severe hypoglycaemic or ketoacidosis events in either group.

CONCLUSIONS

Real-time CGM use in a supportive treat-to-target model of care likely improves glycaemia in a population with insulin-treated T2D and elevated HbA1c.

Continuous glucose monitoring in adults with type 2 diabetes: a systematic review and meta-analysis

AIMS/HYPOTHESIS

Continuous glucose monitoring (CGM) is increasingly used in the treatment of type 2 diabetes, but the effects on glycaemic control are unclear. The aim of this systematic review and meta-analysis is to provide a comprehensive overview of the effect of CGM on glycaemic control in adults with type 2 diabetes.

METHODS

We performed a systematic review using Embase, MEDLINE, Web of Science, Scopus and ClinicalTrials.gov from inception until 2 May 2023. We included RCTs investigating real-time CGM (rtCGM) or intermittently scanned CGM (isCGM) compared with self-monitoring of blood glucose (SMBG) in adults with type 2 diabetes. Studies with an intervention duration <6 weeks or investigating professional CGM, a combination of CGM and additional glucose-lowering treatment strategies or GlucoWatch were not eligible. Change in HbA1c and the CGM metrics time in range (TIR), time below range (TBR), time above range (TAR) and glycaemic variability were extracted. We evaluated the risk of bias using the Cochrane risk-of-bias tool version 2. Data were synthesised by performing a meta-analysis. We also explored the effects of CGM on severe hypoglycaemia and micro- and macrovascular complications.

RESULTS

We found 12 RCTs comprising 1248 participants, with eight investigating rtCGM and four isCGM. Compared with SMBG, CGM use (rtCGM or isCGM) led to a mean difference (MD) in HbA1c of -3.43 mmol/mol (-0.31%; 95% CI -4.75, -2.11, p<0.00001, I2=15%; moderate certainty). This effect was comparable in studies that included individuals using insulin with or without oral agents (MD -3.27 mmol/mol [-0.30%]; 95% CI -6.22, -0.31, p=0.03, I2=55%), and individuals using oral agents only (MD -3.22 mmol/mol [-0.29%]; 95% CI -5.39, -1.05, p=0.004, I2=0%). Use of rtCGM showed a trend towards a larger effect (MD -3.95 mmol/mol [-0.36%]; 95% CI -5.46 to -2.44, p<0.00001, I2=0%) than use of isCGM (MD -1.79 mmol/mol [-0.16%]; 95% CI -5.28, 1.69, p=0.31, I2=64%). CGM was also associated with an increase in TIR (+6.36%; 95% CI +2.48, +10.24, p=0.001, I2=9%) and a decrease in TBR (-0.66%; 95% CI -1.21, -0.12, p=0.02, I2=45%), TAR (-5.86%; 95% CI -10.88, -0.84, p=0.02, I2=37%) and glycaemic variability (-1.47%; 95% CI -2.94, -0.01, p=0.05, I2=0%). Three studies reported one or more events of severe hypoglycaemia and macrovascular complications. In comparison with SMBG, CGM use led to a non-statistically significant difference in the incidence of severe hypoglycaemia (RR 0.66, 95% CI 0.15, 3.00, p=0.57, I2=0%) and macrovascular complications (RR 1.54, 95% CI 0.42, 5.72, p=0.52, I2=29%). No trials reported data on microvascular complications.

CONCLUSIONS/INTERPRETATION

CGM use compared with SMBG is associated with improvements in glycaemic control in adults with type 2 diabetes. However, all studies were open label. In addition, outcome data on incident severe hypoglycaemia and incident microvascular and macrovascular complications were scarce.

REGISTRATION

This systematic review was registered on PROSPERO (ID CRD42023418005).

Effectiveness of Continuous Glucose Monitoring on Metrics of Glycemic Control in Type 2 Diabetes Mellitus: A Systematic Review and Meta-analysis of Randomized Controlled Trials

PURPOSE

To provide a systematic review and meta-analysis synthesizing the findings of randomized controlled trials (RCTs) of continuous glucose monitors (CGMs) in the management of adults with type 2 diabetes mellitus (T2DM) on glucose control and clinical outcomes.

METHODS

MEDLINE, Embase, and Cochrane were searched for RCTs that assessed the effectiveness of real-time CGM (rt-CGM) or flash CGM (FGM) in adults (≥18 years) with T2DM that reported on at least 1 of the following outcomes: hemoglobin A1c (HbA1c), time in range, time in hyperglycemia, or time in hypoglycemia. The GRADE approach was used to assess certainty of evidence for primary outcomes.

RESULTS

Fourteen RCTs assessing CGM were included, with 825 patients in 9 RCTs using rt-CGM and 822 in 5 RCTs using FGM. Moderate certainty of evidence indicated that use of CGM had a modest but statistically significant reduction in HbA1c levels of about 0.32%. Our analyses of each device type separately showed similar reductions in HbA1c (0.34% and 0.33%, respectively, for rt-CGM and FGM), with trends for improvement in other glucose metrics favoring rt-CGM over self-monitored blood glucose.

CONCLUSION

Both rt-CGM and flash CGM led to modest but statistically significant declines in HbA1c among individuals with T2DM, with little heterogeneity in the results. However, the duration of the included RCTs was relatively short and few studies reported on important clinical outcomes, such as adverse events, emergency department use, or hospitalization. Longer term studies are needed to determine if the short-term improvements in glucose control leads to improvements in clinically important outcomes.

Effects of Continuous Glucose Monitoring on Glycemic Control in Type 2 Diabetes: A Systematic Review and Meta-Analysis

As the prevalence of diabetes is rapidly increasing, the use of continuous glucose monitoring, which is effective in improving glycemic control in type 2 diabetes, is increasing.

METHODS

Systematic review was performed according to PRISMA criteria. The search was conducted for articles published until 31 May 2023 in PubMed, CINAHL, Cochrane Library, EMBASE, ClinicalKey, etc. The meta-analysis involved the synthesis of effect size; tests of homogeneity and heterogeneity; trim and fill plot; Egger's regression test; and Begg's test for assessing publication bias.

RESULTS

491 studies were searched, of which 17 studies that met the selection criteria were analyzed. The overall effect on HbA1c was -0.37 (95% CI, -0.63~-0.11, p < 0.001), with HbA1c decreasing significantly after CGM interventions. Sub-analyses showed that the study was statistically significant in those aged 60 years or older, when rt-CGM was used and when the study was performed in multiple centers.

CONCLUSION

The results of this study showed that intervention using CGM was effective in reducing HbA1c in type 2 diabetes. The factors identified in this study can be used as guidelines for developing future CGM intervention programs.

Study protocol: glycaemic outcomes in people with type 2 diabetes initiating continuous glucose monitoring: the 2GO-CGM study

Purpose

Improving glycaemic control in type 2 diabetes (T2D) is essential to reducing social and health-economic burden of diabetes-related complications. Continuous glucose monitoring (CGM) has been established as beneficial in improving glycaemic control and reducing hypoglycaemia in people with type 1 diabetes, however data in T2D is limited. This study has been designed to assess the effect of initiating real-time CGM (rtCGM) on glycaemic control in a high-risk population of adults with T2D. Secondary objectives are to assess the cost-effectiveness and safety of rtCGM, and the effects of rtCGM on diet/lifestyle and the burden of diabetic complications, including cardiovascular risk.

Methods

This multicentre randomised controlled trial (RCT) will be conducted at three sites in New Zealand (Waikato, Christchurch and Dunedin). Eighty adults with T2D on insulin with suboptimal glycaemic control (HbA1c > 8.0% or 64 mmol/mol) will be randomised 1:1 to rtCGM or routine care with self-monitoring of blood glucose levels (SMBG) for three months. This intervention phase will be followed by a three-month continuation phase where SMBG group crossover to use rtCGM. Participants will then be invited to join the extension phase with continued use of rtCGM for a further 12 months. During the extension phase, both groups will independently titrate their insulin under the remote supervision of prescribing diabetes nurse specialists following an insulin titration algorithm. The primary outcome of the study is time in target glucose range (3.9-10 mmol/L or 70-180 mg/dL; TIR). Secondary outcomes include CGM metrics as per consensus statement recommendations, and HbA1c. Additional planned analyses include cardiovascular risk profile, incremental cost-effectiveness analyses, dietary patterns, and qualitative analyses.

Trial registration number

The trial was registered with the Australian New Zealand Clinical Trials Registry (ACTRN12621000889853) on 8 July 2021 and the World Health Organisation International Clinical Trial Registry Platform (Universal Trial Number U1111-1264-5822).

CGMap: Characterizing continuous glucose monitor data in thousands of non-diabetic individuals

Despite its rising prevalence, diabetes diagnosis still relies on measures from blood tests. Technological advances in continuous glucose monitoring (CGM) devices introduce a potential tool to expand our understanding of glucose control and variability in people with and without diabetes. Yet CGM data have not been characterized in large-scale healthy cohorts, creating a lack of reference for CGM data research. Here we present CGMap, a characterization of CGM data collected from over 7,000 non-diabetic individuals, aged 40-70 years, between 2019 and 2022. We provide reference values of key CGM-derived clinical measures that can serve as a tool for future CGM research. We further explored the relationship between CGM-derived measures and diabetes-related clinical parameters, uncovering several significant relationships, including associations of mean blood glucose with measures from fundus imaging and sleep monitoring. These findings offer novel research directions for understanding the influence of glucose levels on various aspects of human health.

Wearable and digital devices to monitor and treat metabolic diseases

Cardiometabolic diseases are a major public-health concern owing to their increasing prevalence worldwide. These diseases are characterized by a high degree of interindividual variability with regards to symptoms, severity, complications and treatment responsiveness. Recent technological advances, and the growing availability of wearable and digital devices, are now making it feasible to profile individuals in ever-increasing depth. Such technologies are able to profile multiple health-related outcomes, including molecular, clinical and lifestyle changes. Nowadays, wearable devices allowing for continuous and longitudinal health screening outside the clinic can be used to monitor health and metabolic status from healthy individuals to patients at different stages of disease. Here we present an overview of the wearable and digital devices that are most relevant for cardiometabolic-disease-related readouts, and how the information collected from such devices could help deepen our understanding of metabolic diseases, improve their diagnosis, identify early disease markers and contribute to individualization of treatment and prevention plans.

Nocturnal hypoglycemia is underdiagnosed in older people with insulin-treated type 2 diabetes: The HYPOAGE observational study

BACKGROUND

There is a lack of real-life data regarding the frequency and predictive factors of hypoglycemia in older patients with type 2 diabetes (T2D). This study aimed to determine the frequency and predictors of hypoglycemia in older patients with insulin-treated T2D.

METHODS

This prospective multicenter study included 155 insulin-treated T2D patients aged 75 years and older with ≥2 self-monitoring of blood glucose (SMBG) daily controls. Participants underwent a geriatric and diabetic assessment and received ambulatory blinded continuous glucose monitoring (CGM) for 28 consecutive days with FreeStyle Libre Pro® sensor. Study population (n = 141) has >70% CGM active time. Multivariable logistic regressions were used to identify factors associated with SMBG confirmed hypoglycemia (≥70 mg/dL) and with nocturnal level 2 time below range (glucose concentration <54 mg/dL during ≥15 consecutive min between 0.00 and 6.00 am).

RESULTS

The mean age of the 141 analyzed patients was 81.5 ± 5.3 years and 56.7% were male. The mean baseline HbA_1c was 7.9% ± 1.0%. After geriatric assessment, 102 participants (72.3%) were considered as complex and 39 (27.7%) as healthy. The primary endpoint (confirmed SMBG <70 mg/dL) occurred in 37.6% patients. In multivariable analysis, the risk of SMBG-confirmed hypoglycemia was positively associated with a longer duration of diabetes (OR (+1 year) =1.04, (1.00-1.08), p = 0.04) and glycemic variability assessed by CGM (CV %) (OR (+1%) = 1.12, [1.05-1.19], p = <0.001). Nighty-two patients (65.2%) experienced nocturnal time in hypoglycemia (i.e., <54 mg/dL during ≥15 consecutive min between midnight and 6 a.m.). In multivariable analyses, cognitive impairment (OR: 9.31 [2.59-33.4]), heart failure (OR: 4.81 [1;48-15.6]), and depressive disorder (OR: 0.19 [0.06-0.53]) were associated with nocturnal time in hypoglycemia.

CONCLUSION

Nocturnal hypoglycemia is very common and largely underdiagnosed in older patients with insulin-treated T2D. CGM is a promising tool to better identify hypoglycemia and adapt diabetes management in this population.

Professional continuous glucose monitoring in patients with diabetes mellitus: A systematic review and meta-analysis

AIM

To evaluate the effect on glucose control of professional continuous glucose monitoring (p-CGM)-based care as compared with standard care in the management of patients with type 1 and type 2 diabetes.

MATERIALS AND METHODS

The PubMed database was searched comprehensively to identify prospective or retrospective studies evaluating p-CGM as a diagnostic tool for subsequent implementation of lifestyle and/or medication changes and reporting glycated haemoglobin (HbA1c) as an outcome measure.

RESULTS

We found 872 articles, 22 of which were included in the meta-analysis. Overall, the use of p-CGM was associated with greater HbA1c reduction from baseline (-0.28%, 95% confidence interval [CI] -0.36% to -0.21%, I²  = 0%, P < 0.00001) than usual care, irrespective of type of diabetes, length of follow-up, frequency of continuous glucose monitoring (CGM) use and duration of CGM recording. In the few studies describing CGM-derived glucose metrics, p-CGM showed a beneficial effect on change in time in range from baseline (5.59%, 95% CI 0.12 to 11.06, I²  = 0%, P = 0.05) and a neutral effect on change in time below the target range from baseline (-0.11%, 95% CI -1.76% to 1.55%, I²  = 33%, P = 0.90).

CONCLUSIONS

In patients with type 1 and type 2 diabetes, p-CGM-driven care is superior to usual care in improving glucose control without increasing hypoglycaemia.

Use of Real-Time Continuous Glucose Monitoring Improves Glycemic Control and Other Clinical Outcomes in Type 2 Diabetes Patients Treated with Less Intensive Therapy

Objective: Use of real-time continuous glucose monitoring (rtCGM) has been shown to improve glycemic control in patients with type 2 diabetes (T2D) who are treated with intensive insulin therapy. However, most T2D patients are denied coverage for rtCGM due to failure to meet payer eligibility requirements: treatment with ≥3 insulin injections (or pump) and history of 4 × /day blood glucose testing. We investigated the relevance of these criteria to successful rtCGM use. Methods: This 6-month, prospective, interventional, single-arm study assessed the clinical effects of use rtCGM in patients with T2D treated with basal insulin only or noninsulin therapy. Primary outcomes were changes in HbA1c, average glucose, glycemic variability (% coefficient of variation), and percent of time in range (%TIR), below range (%TBR) and above range (%TAR). Results: Thirty-eight patients were included in the analysis (10.1% ± 1.8% HbA1c, 54.7 ± 10.2 years, 35.6 ± 6.4 body mass index). At 6 months, we observed reductions in HbA1c (-3.0% ± 1.3%, P < 0.001) and average glucose (-23.6 ± 38.8, P < 0.001). %TIR increased 15.2 ± 22.3, from 57.0 ± 29.9 to 72.2 ± 23.6, P < 0.001, with all patients maintaining %TBR targets (<4% at 70 mg/dL, <1% at <54 mg/dL). No changes in glycemic variability were observed. The greatest improvements in %TIR and %TAR were seen in patients treated with ≤1 medication. Conclusions: rtCGM use was associated with significant glycemic improvements in T2D patients treated with basal insulin only or noninsulin therapy. Given the growing body of evidence supporting rtCGM use in this population, insurance eligibility criteria should be modified to expand rtCGM use by T2D patients treated with less intensive therapies.

Continuous glucose monitoring: A review of the evidence in type 1 and 2 diabetes mellitus

CONTEXT AND AIM

Continuous glucose monitoring (CGM) is becoming widely accepted as an adjunct to diabetes management. Compared to standard care, CGM can provide detailed information about glycaemic variability in an internationally standardised ambulatory glucose profile, enabling more informed user and clinician decision making. We aimed to review the evidence, user experience and cost-effectiveness of CGM.

METHODS

A literature search was conducted by combining subject headings 'CGM' and 'flash glucose monitoring', with key words 'type 1 diabetes' and 'type 2 diabetes', limited to '1999 to current'. Further evidence was obtained from relevant references of retrieved articles.

RESULTS

There is a strong evidence for CGM use in people with type 1 diabetes, with benefits of reduced glycated haemoglobin and hypoglycaemia, and increased time in range. While the evidence for CGM use in type 2 diabetes is less robust, similar benefits have been demonstrated. CGM can improve diabetes-related satisfaction in people with diabetes (PWD) and parents of children with diabetes, as well as the clinician experience. However, CGM does have limitations including cost, accuracy and perceived inconvenience. Cost-effectiveness analyses have indicated that CGM is a cost-effective adjunct to type 1 diabetes management that is associated with reduced diabetes-related complications and hospitalisation.

CONCLUSIONS

Continuous glucose monitoring is revolutionising diabetes management. It is a cost-effective adjunct to diabetes management that has the potential to improve glycaemic outcomes and quality of life in PWD, especially type 1 diabetes.

Cutaneous Complications With Continuous or Flash Glucose Monitoring Use: Systematic Review of Trials and Observational Studies

BACKGROUND

Continuous glucose monitoring (CGM)/flash glucose monitoring (FGM) use in diabetes management is increasing. Cutaneous complications associated with these devices were reported. We conducted a systematic review to provide an overview of cutaneous complications with CGM/FGM use.

METHODS

We identified observational studies and intervention trials that report on cutaneous complications with CGM/FGM use up to January 14, 2019. Studies were identified through Medline, Embase, and PubMed, or with hand searching of the previous publications. Screening was duplicated and data extracted to consider four main themes: incidence rate and severity, participant perspectives of cutaneous complications, potential solutions, and future directions in diabetic technology relevant to reducing cutaneous complications.

RESULTS

A total of 54 eligible studies were identified. The overall event rate of cutaneous complications reported from 19 trials was one event per eight weeks of sensor wear-time of which 1.5% were considered severe. The most common cutaneous complications were wear-related erythema, itching, and induration. Although skin irritations were the most common cause of CGM/FGM discontinuation, most users experienced less pain or discomfort with CGM/FGM than capillary blood glucose testing. Future technological advances may reduce, but not eliminate cutaneous complications.

CONCLUSION

The incidence rate of reported cutaneous complications with CGM/FGM use from the available literature is low, with one event per eight weeks of sensor wear-time. Reported complication severity was also low, leading to low rates of CGM/FGM discontinuation. However, there appear to be discrepancies between reporting in trial and observational data. Greater constancy in reporting is necessary to understand the frequency of this issue.

Use of professional-mode flash glucose monitoring, at 3-month intervals, in adults with type 2 diabetes in general practice (GP-OSMOTIC): a pragmatic, open-label, 12-month, randomised controlled trial

BACKGROUND

Continuous glucose monitoring, either real-time (personal) or retrospective (professional mode), can identify day-to-day glucose profiles to guide management decisions for people with type 2 diabetes. We aimed to examine the effects of professional-mode flash glucose monitoring, done at 3-month intervals, in adults with type 2 diabetes in general practice.

METHODS

We did a pragmatic, two-arm, open label, 12-month, individually randomised controlled trial (GP-OSMOTIC) in 25 general practices in Victoria, Australia. Eligible participants were adults aged 18-80 years, with type 2 diabetes diagnosed for at least 1 year and HbA_1c at least 5·5 mmol/mol (0·5%) above their target in the past month despite being prescribed at least two non-insulin glucose-lowering drugs, insulin, or both (with therapy stable for at least 4 months). We randomly assigned participants (1:1) to either use of a professional-mode flash glucose monitoring system or usual clinical care (control). All participants wore the flash glucose monitoring sensor at baseline, and electronic randomisation (using permuted block sizes of four and six, and stratified by clinic) was done after the sensor was attached. Masking of participants and treating clinicians to group allocation was not possible, but the study statistician was masked to allocation when analysing the data. At baseline, and 3, 6, 9, and 12 months, participants in the flash glucose monitoring group wore the professional-mode flash glucose monitoring sensor for 5-14 days before their general practice visit. The sensor recorded interstitial glucose concentrations every 15 min, but the glucose data were not available to the participant until their general practice visit, where the sensor output would be uploaded to a computer by the health professional and discussed. Control group participants wore the sensor at baseline and at 12 months for data analysis only, and had usual care visits every 3 months. The primary outcome was the between-group difference in mean HbA_1c at 12 months. Secondary outcomes were the between-group differences in: mean percentage time in target glucose range (4-10 mmol/L), based on ambulatory glucose profile data at 12 months; mean diabetes-specific distress (assessed with the Problem Areas In Diabetes [PAID] scale) at 12 months; and mean HbA_1c at 6 months. Analysis was done by intention to treat. This trial is registered at the Australian and New Zealand Clinical Trials Registry, ACTRN12616001372471.

FINDINGS

Between Oct 4, 2016, and Nov 17, 2017, we randomly assigned 299 adults: 149 to flash glucose monitoring and 150 to usual care. At 6 months, HbA_1c was lower in the flash glucose monitoring group than in the usual care group (difference -0·5%, 95% CI -0·8% to -0·3%; p=0·0001). However, at 12 months (primary outcome), there was no significant between-group difference in estimated mean HbA_1c (8·2% [95% CI 8·0 to 8·4] for flash glucose monitoring vs 8·5% [8·3 to 8·7] for usual care; between-group difference -0·3%, 95% CI -0·5 to 0·01; [66 mmol/mol, 95% CI 64 to 68 vs 69 mmol/mol, 67 to 72; between-group difference -3·0, 95% CI -5·0 to 0·1]; p=0·059). Mean percentage time spent in target glucose range at 12 months was 7·9% (95% CI 2·3 to 13·5) higher in the flash glucose monitoring group than in the usual care group (p=0·0060). Diabetes-specific distress PAID scores were unchanged at 12 months (between-group difference -0·7, 95% CI -3·3 to 1·9; p=0·61). No episodes of severe hypoglycaemia or treatment-related deaths were reported. One participant died during the study from causes unrelated to the intervention (following complications post-myocardial infarction with multiple comorbidities).

INTERPRETATION

Professional-mode flash glucose monitoring in adults with type 2 diabetes in general practice did not improve the primary outcome of HbA_1c at 12 months or diabetes-specific distress compared with usual care, but did improve time in target glucose range at 12 months and HbA_1c at 6 months. Our findings suggest that professional-mode flash glucose monitoring can be implemented in a pragmatic primary care environment. Although there was no change in HbA_1c at 12 months, the improved time in target range might reflect the potential of the technology to support personalised clinical care by providing insights into glycaemic profiles for some people with type 2 diabetes.

FUNDING

National Health and Medical Research Council of Australia, Sanofi Australia, and Abbott Diabetes Care.

Continuous Glucose Monitoring Versus Self-monitoring of Blood Glucose in Type 2 Diabetes Mellitus: A Systematic Review with Meta-analysis

Every eleventh adult has diabetes, and every third has prediabetes. Over 95% of diabetics are of type 2. It is well established that diabetes doubles the risk of heart disease and stroke apart from increasing the risk of microvascular complications. Hence, strict glycemic control is necessary. However, it increases the risk of hypoglycemia, especially in patients with longstanding diabetes. Continuous glucose monitors (CGM) use a sensor to continuously measure the glucose levels in the interstitial fluid every 10 seconds and gives out mean values every five minutes. CGMs are emerging tools in the management of type 2 diabetes. The prime objective of this review is to find out if there is enough supporting evidence, suggesting that continuous glucose monitoring is more effective than self-monitoring of blood glucose (SMBG) in type 2 diabetes. We conducted a systematic literature search in Medline (PubMed) looking for any studies addressing our objective. It is observed that there is a varying level of evidence supporting that employing a CGM can reduce glycated hemoglobin (HbA1c), hypoglycemic events, and increase patient satisfaction. However, some studies reported no significant benefits. This systematic review with meta-analysis concludes that the use of CGM in type 2 diabetes mellitus (T2DM) is beneficial, as it significantly reduces HbA1c compared to the usual method of SMBG. The pooled mean difference in HbA1c was -0.25 (-0.45, -0.06) and statistically significant (at p = 0.01) when comparing CGM to SMBG.

Reduction in HbA1c using professional flash glucose monitoring in insulin-treated type 2 diabetes patients managed in primary and secondary care settings: A pilot, multicentre, randomised controlled trial

AIM

Analyse the effects of professional flash glucose monitoring system (FreeStyle Libre Pro™) on glycaemic control in insulin-treated type 2 diabetes.

METHODS

Primary (n = 17) and secondary care centres (n = 5) randomised 148 type 2 diabetes patients into three groups: (A) self-monitoring of blood glucose (n = 52), (B) self-monitoring of blood glucose and two Libre Pro sensor wears (n = 46) or (C) self-monitoring of blood glucose and four sensor wears (n = 50). Primary endpoint was time in range (glucose 3.9-10 mmol/L) within group C comparing baseline with days 172-187. Predefined secondary endpoints included HbA1c, hypoglycaemia and quality of life measures analysed within and between groups (clinicaltrials.gov, NCT02434315).

RESULTS

In group C, time in range in the first 14 days (baseline) and days 172-187 was similar at 15.0 ± 5.0 and 14.1 ± 4.7 h/day (mean ± SD), respectively, (p = 0.1589). In contrast, HbA1c reduced from baseline to study end within group C by 4.9 ± 8.8 mmol/mol (0.44% ± 0.81%; p = 0.0003). HbA1c was also lower in group C compared with A at study end by 5.4 ± 1.79 mmol/mol (0.48% ± 0.16%; p = 0.0041, adjusted mean ± SE), without increased time in hypoglycaemia (p = 0.1795). Treatment satisfaction scores improved in group C compared with A (p = 0.0225) and no device-related serious adverse events were reported.

CONCLUSIONS

Libre Pro can improve HbA1c and treatment satisfaction without increasing hypoglycaemic exposure in insulin-treated type 2 diabetes individuals managed in primary/secondary care centres.

Utility of Real-Time and Retrospective Continuous Glucose Monitoring in Patients with Type 2 Diabetes Mellitus: A Meta-Analysis of Randomized Controlled Trials

In the present study, we aimed to investigate the effects of continuous glucose monitoring (CGM) on blood glucose levels, body weight, blood pressure, and hypoglycaemia in patients with type 2 diabetes mellitus using a meta-analysis of randomized controlled trials (RCTs). A literature search was performed using MEDLINE, Cochrane Controlled Trials Registry, and ClinicalTrials.gov. RCTs using CGM in patients with type 2 diabetes mellitus were then selected. Statistical analysis included calculation of the standardized mean difference (SMD) or risk ratio and 95% confidence intervals (CIs) using a random effects model. After literature search, seven RCTs (669 patients) satisfied the eligibility criteria established herein and were included into the meta-analysis. Compared with the self-monitoring blood glucose group, the CGM group exhibited significantly lower HbA1c levels (SMD, -0.35; 95% CI, -0.59--0.10; P = 0.006) and shorter time spent with hypoglycaemia (SMD, -0.42; 95% CI, -0.70--0.13; P = 0.004). Conversely, no differences in body weight and blood pressure were observed between the groups. CGM in patients with type 2 diabetes mellitus could reduce HbA1c levels and time spent with hypoglycaemia. However, because few RCTs were included in this present study and heterogeneity was also noted, care should be taken when interpreting the results.

Continuous glucose monitoring: a review of the evidence, opportunities for future use and ongoing challenges

The advent of devices that can track interstitial glucose levels, which are closely related to blood glucose levels, on a near continuous basis, has facilitated better insights into patterns of glycaemia. Continuous glucose monitoring (CGM) therefore allows for more intensive monitoring of blood glucose levels and potentially improved glycaemic control. In the context of the announcement on 1 April 2017 that the Australian Government will fund CGM monitoring for people with type 1 diabetes under the age of 21 years, this paper provides a review of the evidence for CGM and some of the ongoing challenges. There is evidence that real-time CGM in type 1 diabetes improves HbA1c and hypoglycaemia, while in type 2 diabetes, the evidence is less robust. Initial barriers to widespread implementation of CGM included issues with accuracy and user friendliness; however, as the technology has evolved, these issues have largely improved. Ongoing barriers include cost, and weaker evidence for their benefit in certain populations such as those with type 2 diabetes and less glycaemic variability. CGM has the potential to reduce healthcare costs, although real-world studies, including cost-effectiveness analyses, are needed in this area.

The Effectiveness of Continuous Glucose Monitoring in Patients with Type 2 Diabetes: A Systematic Review of Literature and Meta-analysis

BACKGROUND

Continuous glucose monitoring (CGM) provides glucose trend information that can be used to guide treatment and motivate patients with diabetes. Currently, the evidence on effectiveness of CGM in patients with type 2 diabetes is debatable. We aim to provide a systematic review and meta-analysis to synthesize current evidence of effectiveness of CGM in adults with type 2 diabetes.

MATERIALS AND METHODS

Cochrane, Embase, PubMed, and Web of Science were searched to include all studies that reported effectiveness of CGM in terms of HbA1c in adults aged 18 and older, with type 2 diabetes, on any treatment for diabetes. Heterogeneity (I²) was used to determine the variability between studies. All data were analyzed using Review Manager 5.3 software.

RESULTS

Seven randomized controlled trials and three cohort studies, involving 1384 patients for real-time CGM (RT-CGM) and professional CGM (P-CGM) and 4902 patients for flash glucose monitoring (FGM), were included. RT-CGM and P-CGM were associated with a modest but statistically significant reduction in HbA1c of 0.20% (95% confidence interval [CI] -0.31 to -0.09) compared with control. Patients who received FGM had a nonsignificant reduction of 0.02% (95% CI -0.07 to 0.04) compared with control. The meta-analysis indicated a low heterogeneity between studies.

CONCLUSION

Our analysis of current evidence suggests that RT-CGM and P-CGM are effective in improving HbA1c in adults with type 2 diabetes. Due to insufficient evidence, it is premature to form conclusions on the effectiveness of FGM. Future multicenter trials accessing the effectiveness of CGM as well as safety and cost-effectiveness may be necessary.

Clinical and economic benefits of professional CGM among people with type 2 diabetes in the United States: analysis of claims and lab data

BACKGROUND

It is estimated that one in 10 people in the US have a diagnosis of diabetes. Type 2 diabetes accounts for 95% of all cases in the US, with annual costs estimated to be $246 billion per year. This study investigated the impact of a glucose-measuring intervention to the burden of type 2 diabetes.

OBJECTIVE

This analysis seeks to understand how professional continuous glucose monitoring (professional CGM) impacts clinical and economic outcomes when compared to patients who are not prescribed professional CGM.

METHODS

This study utilized a large healthcare claims and lab dataset from the US, and identified a cohort of patients who were prescribed professional CGM as identified by CPT codes 95250 and 95251. It calculated economic and clinical outcomes 1 year before and 1 year after the use of professional CGM, using a generalized linear model.

RESULTS

Patients who utilized professional CGM saw an improvement in hemoglobin A1C. The "difference-in-difference" calculation for A1C was shown to be -0.44%. There was no statistically significant difference in growth of total annual costs for people who used professional CGM compared to those who did not ($1,270, p = .08). Patients using professional CGM more than once per year had a -$3,376 difference in the growth of total costs (p = .05). Patients who used professional CGM while changing their diabetes treatment regimen also had a difference of -$3,327 in growth of total costs (p = .0023).

CONCLUSION

Significant clinical benefits were observed for patients who used professional CGM. Economic benefits were observed for patients who utilized professional CGM more than once within a 1-year period or who used it during a change of diabetes therapy. This suggests that professional CGM may help decrease rising trends in healthcare costs for people with type 2 diabetes, while also improving clinical outcomes.

Continuous Glucose Monitoring with Multiple Daily Insulin Treatment: Outcome Studies

Continuous glucose monitoring (CGM) is developing into an increasingly useful tool for glucose monitoring and therapeutic guidance in the treatment of diabetes. Multiple daily doses of insulin (MDI) is the most common method for intensive insulin treatment of type 1 diabetes and is also becoming more common in the treatment of type 2 diabetes as an increasing population with type 2 diabetes experiences progressive beta cell loss. The clinical evidence demonstrating the benefit of CGM in the outcomes of patients treated with MDI is becoming clearer, particularly with the recent completion of several randomized clinical trials addressing both type 1 and 2 diabetes. This evidence is reviewed.

Role of continuous glucose monitoring for type 2 in diabetes management and research

The advent of continuous glucose monitoring (CGM) is a significant stride forward in our ability to better understand the glycemic status of our patients. Current clinical practice employs two forms of CGM: professional (retrospective or "masked") and personal (real-time) to evaluate and/or monitor glycemic control. Most studies using professional and personal CGM have been done in those with type 1 diabetes (T1D). However, this technology is agnostic to the type of diabetes and can also be used in those with type 2 diabetes (T2D). The value of professional CGM in T2D for physicians, patients, and researchers is derived from its ability to: (1) to discover previously unknown hyper- and hypoglycemia (silent and symptomatic); (2) measure glycemic control directly rather than through the surrogate metric of hemoglobin A1C (HbA1C) permitting the observation of a wide variety of metrics that include glycemic variability, the percent of time within, below and above target glucose levels, the severity of hypo- and hyperglycemia throughout the day and night; (3) provide actionable information for healthcare providers derived by the CGM report; (4) better manage patients on hemodialysis; and (5) effectively and efficiently analyze glycemic effects of new interventions whether they be pharmaceuticals (duration of action, pharmacodynamics, safety, and efficacy), devices, or psycho-educational. Personal CGM has also been successfully used in a small number of studies as a behavior modification tool in those with T2D. This comprehensive review describes the differences between professional and personal CGM and the evidence for the use of each form of CGM in T2D. Finally, the opinions of key professional societies on the use of CGM in T2D are presented.

Sensor and software use for the glycaemic management of insulin-treated type 1 and type 2 diabetes patients

Lowering glucose levels, while avoiding hypoglycaemia, can be challenging in insulin-treated patients with diabetes. We evaluated the role of ambulatory glucose profile in optimising glycaemic control in this population. Insulin-treated patients with type 1 and type 2 diabetes were recruited into a prospective, multicentre, 100-day study and randomised to control (n = 28) or intervention (n = 59) groups. The intervention group used ambulatory glucose profile, generated by continuous glucose monitoring, to assess daily glucose levels, whereas the controls relied on capillary glucose testing. Patients were reviewed at days 30 and 45 by the health care professional to adjust insulin therapy. Comparing first and last 2 weeks of the study, ambulatory glucose profile-monitored type 2 diabetes patients (n = 28) showed increased time in euglycaemia (mean ± standard deviation) by 1.4 ± 3.5 h/day (p = 0.0427) associated with reduction in HbA1c from 77 ± 15 to 67 ± 13 mmol/mol (p = 0.0002) without increased hypoglycaemia. Type 1 diabetes patients (n = 25) showed reduction in hypoglycaemia from 1.4 ± 1.7 to 0.8 ± 0.8 h/day (p = 0.0472) associated with a marginal HbA1c decrease from 75 ± 10 to 72 ± 8 mmol/mol (p = 0.0508). Largely similar findings were observed comparing intervention and control groups at end of study. In conclusion, ambulatory glucose profile helps glycaemic management in insulin-treated diabetes patients by increasing time spent in euglycaemia and decreasing HbA1c in type 2 diabetes patients, while reducing hypoglycaemia in type 1 diabetes patients.

The Contemporary Role of Masked Continuous Glucose Monitoring in a Real-Time World

Real-time continuous glucose monitoring (RT-CGM) has, in the span of just a few years, established an essential role in the contemporary management of type 1 diabetes. Nonetheless, masked CGM retains an important place in the management of diabetes including assisting with hypoglycemia detection and avoidance, optimizing glycemic control, and acting as a teaching tool for people living with diabetes.

High incidence of hypoglycemia in stable insulin-treated type 2 diabetes mellitus: continuous glucose monitoring vs. self-monitored blood glucose. Observational prospective study

OBJECTIVES

Hypoglycemia is a limiting factor in the achievement of strict glycemic control. The primary objective of this 9-week study was to determine the frequency of hypoglycemia in patients with stable insulin-treated type 2 diabetes mellitus by comparing self-monitored blood glucose (SMBG) measurement with continuous glucose monitoring (CGM).

METHODS

This was an observational prospective study. Included in the study were 63 stable, insulin-treated patients with type 2 diabetes. They were instructed to record 2 daily capillary blood glucose readings, pre- and/or postprandial, in a sequential way during 8 consecutive weeks. A CGM system was worn during an additional week. We evaluated the frequency of hypoglycemia using the 8-week SMBG profile and the 1 CGM week.

RESULTS

SMBG revealed that 50% of the patients had experienced hypoglycemia. CGM found hypoglycemia in 59% of patients. Significantly higher percentages of hyperglycemic and hypoglycemic episodes were detected by CGM than by capillary blood glucose measurements (61.1% vs. 50.8%; p=0.047) and (3.8% vs. 1.7%; p=0.016); 33% of patients experienced nocturnal hypoglycemia, and 19% of patients who had no data concerning hypoglycemia recorded in the capillary blood glucose diary had experienced hypoglycemia as measured by CGM, and the hypoglycemia occurred mainly during the nocturnal period.

CONCLUSIONS

In stable well-controlled, insulin-treated patients with type 2 diabetes, CGM showed higher numbers of hypoglycemic events than did SMBG, especially at night. CGM is a useful tool that provides clinically valuable information about glucose control in these patients.

Real-time continuous glucose monitoring versus internet-based blood glucose monitoring in adults with type 2 diabetes: a study of treatment satisfaction

AIMS

To compare treatment satisfaction between real-time continuous glucose monitoring (RT-CGM) and internet-blood glucose monitoring (IBGM) in adults with type 2 diabetes treated with insulin.

METHODS

This study recruited 40 patients who completed a parallel randomized controlled trial comparing a RT-CGM to an IBGM. Patients in the RT-CGM group monitored their blood-glucose levels bi-weekly and emailed results to their endocrinologist. Patients in the IBGM group also monitored their blood-glucose levels bi-weekly, but entered their data into an IBGM. Both groups used a secure website to submit blood-glucose readings and to receive feedback from their endocrinologist. Feedback included changes in therapy, suggestions on testing frequency, lifestyle modifications and/or encouragement to continue with no changes. At the end of 6 months, treatment satisfaction was measured using the 8-item Diabetes Treatment Satisfaction Questionnaire. In this study, "treatment" refers to the blood glucose monitoring system to which patients were randomized.

RESULTS

Thirty-two of the 40 patients completed the treatment satisfaction questionnaire (80%). Compared to the RT-CGM group, the IBGM group reported a significantly higher level of overall treatment satisfaction (24.80 vs. 33.41, p<0.000). Ratings of individual satisfaction components including convenience, flexibility, likelihood of recommending treatment to others, and willingness to continue with treatment were also found to be significantly higher in the IBGM group.

CONCLUSION

Patients using IBGM are more satisfied with their blood glucose monitoring system compared to those using RT-CGM.

Interstitium versus Blood Equilibrium in Glucose Concentration and its Impact on Subcutaneous Continuous Glucose Monitoring Systems

The relationship between both interstitial and blood glucose remains a debated topic, on which there is still no consensus. The experimental evidence suggests that blood and interstitial fluid glucose levels are correlated by a kinetic equilibrium, which as a consequence has a time and magnitude gradient in glucose concentration between blood and interstitium. Furthermore, this equilibrium can be perturbed by several physiological effects (such as foreign body response, wound-healing effect, etc.), with a consequent reduction of interstitial fluid glucose versus blood glucose correlation. In the present study, the impact of operating in the interstitium on continuous glucose monitoring systems (CGMs) will be discussed in depth, both for the application of CGMs in the management of diabetes and in other critical areas, such as tight glycaemic control in critically ill patients.

Systematic review and meta-analysis of the effectiveness of continuous glucose monitoring (CGM) on glucose control in diabetes

Diabetes mellitus is a chronic disease that necessitates continuing treatment and patient self-care education. Monitoring of blood glucose to near normal level without hypoglycemia becomes a challenge in the management of diabetes. Although self monitoring of blood glucose (SMBG) can provide daily monitoring of blood glucose level and help to adjust therapy, it cannot detect hypoglycemic unawareness and nocturnal hypoglycemia which occurred mostly in T1DM pediatrics. Continuous glucose monitoring (CGM) offers continuous glucose data every 5 minutes to adjust insulin therapy especially for T1DM patients and to monitor lifestyle intervention especially for T2DM patients by care providers or even patients themselves. The main objective of this study was to assess the effects of continuous glucose monitoring (CGM) on glycemic control in Type 1 diabetic pediatrics and Type 2 diabetic adults by collecting randomized controlled trials from MEDLINE (pubmed), SCOPUS, CINAHL, Web of Science and The Cochrane Library up to May 2013 and historical search through the reference lists of relevant articles. There are two types of CGM device: real-time CGM and retrospective CGM and both types of the device were included in the analysis. In T1DM pediatrics, CGM use was no more effective than SMBG in reducing HbA1c [mean difference - 0.13% (95% CI -0.38% to 0.11%,]. This effect was independent of HbA1c level at baseline. Subgroup analysis indicated that retrospective CGM was not superior to SMBG [mean difference -0.05% (95% CI -0.46% to 0.35%)]. In contrast, real-time CGM revealed better effect in lowering HbA1c level compared with SMBG [mean difference -0.18% (95% CI -0.35% to -0.02%, p = 0.02)]. In T2DM adults, significant reduction in HbA1c level was detected with CGM compared with SMBG [mean difference - 0.31% (95% CI -0.6% to -0.02%, p = 0.04)]. This systematic review and meta-analysis suggested that real-time CGM can be more effective than SMBG in T1DM pediatrics, though retrospective CGM was not. CGM provided better glycemic control in T2DM adults compared with SMBG.

Comparative analysis of the efficacy of continuous glucose monitoring and self-monitoring of blood glucose in type 1 diabetes mellitus

BACKGROUND

Self-monitoring of blood glucose (SMBG) and continuous glucose monitoring (CGM) have been proven effective in improving hemoglobin A1c (HbA1c) and in reducing hypoglycemia in patients with type 1 diabetes mellitus (T1DM). It is not clear, however, if CGM provides further efficacy and safety benefits beyond SMBG in the management of T1DM.

METHODS

MEDLINE (1966-November 2009), COCHRANE REGISTRY (all years), and EMBASE (1980-November 2009), and article bibliographies were searched for randomized controlled trials (RCTs) investigating the use of CGM in patients with T1DM, with clinical outcomes, including HbA1c and hypoglycemia and/or hyperglycemia.

RESULTS

Fourteen RCTs met eligibility criteria [n = 1188 patients, 97.4% with T1DM, age 29.0 ± 14.3 years, diabetes duration 11.7 ± 7.0 years, and baseline HbA1c 8.3 ± 0.8% (mean ± standard deviation)]. Compared with SMBG, the use of CGM was associated with a greater reduction in HbA1c [-0.3% (confidence interval: 0.4, -0.2), p < .0001]. The number of hypoglycemic events was not significantly different between the CGM and SMBG groups (0.52 ± 0.52 versus 0.52 ± 0.63 events/day, p = .5), but duration of hypoglycemia was shorter for the CGM group (75 ± 39 versus 89 ± 19 min/day), with an incremental reduction of hypoglycemia duration of -15.2 min/day, p < .0001. Continuous glucose monitoring also resulted in a shorter duration of hyperglycemia than SMBG (172 ± 125 versus 217 ± 152 min/day, p = .04).

CONCLUSIONS

The use of CGM is associated with improvement in metabolic control in T1DM, with significant short- and long-term reductions in HbA1c and reduction in the duration of periods of hypoglycemia and hyperglycemia versus SMBG.

Intraindividual differences between two simultaneous glucose measurement systems in type 2 diabetic patients

AIMS

Continuous glucose measurement systems are an established tool to support diabetes therapy. Because of different technical solutions one can propose different potential limitations in daily practice. So we tried to identify the accuracy of two different devices head to head in daily routine to point out individual characteristics.

METHODS

We included 24 patients with type 2 diabetes mellitus to wear the GlucoDay and the MiniMed continuous glucose measurement system at the same time for 48 h. We examined the mean differences in simultaneous glucose measurements, the confidence intervals were calculated by standard methods based on the t-distribution.

RESULTS

Comparison of glucose levels of both continuous glucose measurement systems showed that there was a tendency for higher glucose levels measured by the GlucoDay device. These differences were dependent on the time of the day. The absolute difference between two consecutive glucose measurements was higher for the GlucoDay system what means a somehow higher fluctuation of the GlucoDay measurements.

CONCLUSIONS

The differences in intraindividual comparison of the GlucoDay and the MiniMed continuous glucose measurement systems in type 2 diabetic patients may be taken into account when using different systems for detection of nocturnal hypoglycemia and the observation of trends used for therapeutic decisions.

Continuous glucose monitoring systems for type 1 diabetes mellitus

BACKGROUND

Self-monitoring of blood glucose is essential to optimise glycaemic control in type 1 diabetes mellitus. Continuous glucose monitoring (CGM) systems measure interstitial fluid glucose levels to provide semi-continuous information about glucose levels, which identifies fluctuations that would not have been identified with conventional self-monitoring. Two types of CGM systems can be defined: retrospective systems and real-time systems. Real-time systems continuously provide the actual glucose concentration on a display. Currently, the use of CGM is not common practice and its reimbursement status is a point of debate in many countries.

OBJECTIVES

To assess the effects of CGM systems compared to conventional self-monitoring of blood glucose (SMBG) in patients with diabetes mellitus type 1.

SEARCH METHODS

We searched The Cochrane Library, MEDLINE, EMBASE and CINAHL for the identification of studies. Last search date was June 8, 2011.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing retrospective or real-time CGM with conventional self-monitoring of blood glucose levels or with another type of CGM system in patients with type 1 diabetes mellitus. Primary outcomes were glycaemic control, e.g. level of glycosylated haemoglobin A1c (HbA1c) and health-related quality of life. Secondary outcomes were adverse events and complications, CGM derived glycaemic control, death and costs.

DATA COLLECTION AND ANALYSIS

Two authors independently selected the studies, assessed the risk of bias and performed data-extraction. Although there was clinical and methodological heterogeneity between studies an exploratory meta-analysis was performed on those outcomes the authors felt could be pooled without losing clinical merit.

MAIN RESULTS

The search identified 1366 references. Twenty-two RCTs meeting the inclusion criteria of this review were identified. The results of the meta-analyses (across all age groups) indicate benefit of CGM for patients starting on CGM sensor augmented insulin pump therapy compared to patients using multiple daily injections of insulin (MDI) and standard monitoring blood glucose (SMBG). After six months there was a significant larger decline in HbA1c level for real-time CGM users starting insulin pump therapy compared to patients using MDI and SMBG (mean difference (MD) in change in HbA1c level -0.7%, 95% confidence interval (CI) -0.8% to -0.5%, 2 RCTs, 562 patients, I(2)=84%). The risk of hypoglycaemia was increased for CGM users, but CIs were wide and included unity (4/43 versus 1/35; RR 3.26, 95% CI 0.38 to 27.82 and 21/247 versus 17/248; RR 1.24, 95% CI 0.67 to 2.29). One study reported the occurrence of ketoacidosis from baseline to six months; there was however only one event. Both RCTs were in patients with poorly controlled diabetes.For patients starting with CGM only, the average decline in HbA1c level six months after baseline was also statistically significantly larger for CGM users compared to SMBG users, but much smaller than for patients starting using an insulin pump and CGM at the same time (MD change in HbA1c level -0.2%, 95% CI -0.4% to -0.1%, 6 RCTs, 963 patients, I(2)=55%). On average, there was no significant difference in risk of severe hypoglycaemia or ketoacidosis between CGM and SMBG users. The confidence interval however, was wide and included a decreased as well as an increased risk for CGM users compared to the control group (severe hypoglycaemia: 36/411 versus 33/407; RR 1.02, 95% CI 0.65 to 1.62, 4 RCTs, I(2)=0% and ketoacidosis: 8/411 versus 8/407; RR 0.94, 95% CI 0.36 to 2.40, 4 RCTs, I(2)=0%).Health-related quality of life was reported in five of the 22 studies. In none of these studies a significant difference between CGM and SMBG was found. Diabetes complications, death and costs were not measured.There were no studies in pregnant women with diabetes type 1 and in patients with hypoglycaemia unawareness.

AUTHORS' CONCLUSIONS

There is limited evidence for the effectiveness of real-time continuous glucose monitoring (CGM) use in children, adults and patients with poorly controlled diabetes. The largest improvements in glycaemic control were seen for sensor-augmented insulin pump therapy in patients with poorly controlled diabetes who had not used an insulin pump before. The risk of severe hypoglycaemia or ketoacidosis was not significantly increased for CGM users, but as these events occurred infrequent these results have to be interpreted cautiously.There are indications that higher compliance of wearing the CGM device improves glycosylated haemoglobin A1c level (HbA1c) to a larger extent. 

Efficacy of continuous glucose monitoring in improving glycemic control and reducing hypoglycemia: a systematic review and meta-analysis of randomized trials

OBJECTIVE

We conducted a systematic review and meta-analysis to assess the efficacy of continuous glucose monitoring (CGM) in improving glycemic control and reducing hypoglycemia compared to self-monitored blood glucose (SMBG).

METHODS

We searched MEDLINE, EMBASE, Cochrane Central, Web of Science, and Scopus for randomized trials of adults and children with type 1 or type 2 diabetes mellitus (T1DM or T2DM). Pairs of reviewers independently selected studies, assessed methodological quality, and extracted data. Meta-analytic estimates of treatment effects were generated using a random-effects model.

RESULTS

Nineteen trials were eligible and provided data for meta-analysis. Overall, CGM was associated with a significant reduction in mean hemoglobin A1c [HbA1c; weighted mean difference (WMD) of -0.27% (95% confidence interval [CI] -0.44 to -0.10)]. This was true for adults with T1DM as well as T2DM [WMD -0.50% (95% CI -0.69 to -0.30) and -0.70 (95% CI, -1.14 to -0.27), respectively]. No significant effect was noted in children and adolescents. There was no significant difference in HbA1c reduction between studies of real-time versus non-realtime devices (WMD -0.22%, 95% CI, -0.59 to 0.15 versus -0.30%, 95% CI, -0.49 to -0.10; p for interaction 0.71). The quality of evidence was moderate due to imprecision, suggesting increased risk for bias. Data for the incidence of severe or nocturnal hypoglycemia were sparse and imprecise. In studies that reported patient satisfaction, users felt confident about the device and gave positive reviews.

CONCLUSION

Continuous glucose monitoring seems to help improve glycemic control in adults with T1DM and T2DM. The effect on hypoglycemia incidence is imprecise and unclear. Larger trials with longer follow-up are needed to assess the efficacy of CGM in reducing patient-important complications without significantly increasing the burden of care for patients with diabetes.