Role of continuous glucose monitoring in diabetic patients at high cardiovascular risk: an expert-based multidisciplinary Delphi consensus

(2022) 21:164 Di Mario et al. Cardiovascular Diabetology https://doi.org/10.1186/s12933-022-01598-2 Cardiovascular Diabetology Open Access RESEARCH Role of continuous glucose monitoring in diabetic patients at high cardiovascular risk: an expert‑based multidisciplinary Delphi consensus Carlo Di Mario1, Stefano Genovese2*, Gaetano A. Lanza3, Edoardo Mannucci4, Giancarlo Marenzi5, Edoardo Sciatti6 and Dario Pitocco7 on behalf of the Expert Panel Group Abstract Background: Continuous glucose monitoring (CGM) shows in more detail the glycaemic pattern of diabetic subjects and provides several new parameters (“glucometrics”) to assess patients’ glycaemia and consensually guide treatment. A better control of glucose levels might result in improvement of clinical outcome and reduce disease complications. This study aimed to gather an expert consensus on the clinical and prognostic use of CGM in diabetic patients at high cardiovascular risk or with heart disease. Methods: A list of 22 statements concerning type of patients who can benefit from CGM, prognostic impact of CGM in diabetic patients with heart disease, CGM use during acute cardiovascular events and educational issues of CGM were developed. Using a two-round Delphi methodology, the survey was distributed online to 42 Italian experts (21 diabetologists and 21 cardiologists) who rated their level of agreement with each statement on a 5-point Likert scale. Consensus was predefined as more than 66% of the panel agreeing/disagreeing with any given statement. Results: Forty experts (95%) answered the survey. Every statement achieved a positive consensus. In particular, the panel expressed the feeling that CGM can be prognostically relevant for every diabetic patient (70%) and that is clinically useful also in the management of those with type 2 diabetes not treated with insulin (87.5%). The assessment of time in range (TIR), glycaemic variability (GV) and hypoglycaemic/hyperglycaemic episodes were considered relevant in the management of diabetic patients with heart disease (92.5% for TIR, 95% for GV, 97.5% for time spent in hypoglycaemia) and can improve the prognosis of those with ischaemic heart disease (100% for hypoglycaemia, 90% for hyperglycaemia) or with heart failure (87.5% for hypoglycaemia, 85% for TIR, 87.5% for GV). The experts retained that CGM can be used and can impact the short- and long-term prognosis during an acute cardiovascular event. Lastly, CGM has a recognized educational role for diabetic subjects. Conclusions: According to this Delphi consensus, the clinical and prognostic use of CGM in diabetic patients at high cardiovascular risk is promising and deserves dedicated studies to confirm the experts’ feelings. *Correspondence: 2 Diabetes, Endocrine and Metabolic Diseases Unit, Centro Cardiologico Monzino IRCCS, Milan, Italy Full list of author information is available at the end of the article © The Author(s) 2022. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativeco mmons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Di Mario et al. Cardiovascular Diabetology (2022) 21:164 Page 2 of 10 Keywords: Delphi method, Continuous glucose monitoring, Cardiovascular outcome, Time in range, Glycaemic variability, Glucometrics Background Self-monitoring of blood glucose (SMBG) has until now been the most widely used method by patients with diabetes to assess their own glycaemia and guide diabetes treatment. On the other hand, glycated haemoglobin A1c (HbA1c) is the primary tool for assessing glycaemic control and has a strong predictive value for diabetes complications [1–6]. However, both these established methods of diabetes assessment present well-known limitations. SMBG only provides data at a single point, is time consuming, inconvenient, and painful, often leading to poor adherence [7]. HbA1c only reflects the average glycaemia of the last 3 months, is not reliable in the presence of some pathological conditions such as anaemia and does not give information on blood glucose fluctuations caused by food intake, physical activity, medication or any other physical or emotional stress. In the last decade techniques have been developed that allow continuous monitoring of blood glucose levels, which provide the unique opportunity to analyse in detail, even for several days, the glycaemic pattern (i.e., glucose levels and their variations) of diabetic patients [8]. Continuous glucose monitoring (CGM) devices use a fixed sensor with a subcutaneous glucose-oxidase platinum electrode that measures glucose concentrations in the interstitial fluids [9]. They either continuously track the glucose concentration providing real-time data, namely real-time CGM (rtCGM), or show continuous measurements intermittently scanned “on-demand”, namely intermittently scanned CGM (isCGM) or flash glucose monitoring (FGM) [10]. CGM provides several new parameters (“glucometrics”) that may better reflect patients’ glycaemic values and consensually improve their treatment. Importantly, some data suggest that the management of diabetic patients by CGM might also improve clinical outcome and reduce the risk of complications [10]. The most important of the glucometrics derived from CGM include the time in range (TIR), defined as the time with glycaemia fitting among two cut-offs of 70 and 180 g/dL [11], and glycaemic variability (GV), which reflects the amplitude and the frequency of glycaemic fluctuations [12, 13]. CGM derived glucometrics overcome the main issues related to SMBG and HBA1c providing novel, easy-to-get and unpainful data about glucose fluctuations, including the detection of relevant hyperglycaemic and, even more, hypoglycaemic events [13], which have consistently been associated with a worse clinical outcome in diabetic patients [14]. Taken together, these considerations let a recent consensus of diabetologists acknowledge the obsolescence of SMBG and limitations of HbA1c, highlighting the need of using new tools and glucometrics to improve glycaemic control and ther (...truncated)