Increased glucose variability is associated with atrial fibrillation after coronary artery bypass

Short-term Glycemic Variability and Its Association With Macrovascular and Microvascular Complications in Patients With Diabetes

The introduction of continuous glucose monitoring inaugurated a new era in clinical practice by shifting the characterization of glycemic control from HbA1c to novel metrics. The one that gained widespread attention over the past decades was glycemic variability (GV), which typically refers to peaks and nadirs of blood glucose measured over a given time interval. GV can be dichotomized into two main categories: short-term and long-term. Short-term GV reflects within-day and between-day glycemic oscillations, and its contribution to diabetic complications remains an enigma. In this review, we summarize the available data about short-term GV and its possible association with both microvascular and macrovascular complications, evaluating different pathogenic mechanisms and demonstrating nonpharmaceutical, as well as pharmaceutical, therapeutic interventions.

Continuous Glucose Monitoring System After Coronary Artery Bypass Graft Surgery: A Feasibility Study

BACKGROUND

Blood glucose level variability has been associated with increased risk of complication in the postoperative setting of cardiovascular surgery. Although interesting for optimization of blood glucose management in this context, continuous blood glucose (CBG) devices can have a limited reliability in this context, in particular because of the use of paracetamol. The aim of this study was to evaluate the reliability of Dexcom G6®, a recently developed continuous glucose monitoring device.

METHODS

We performed a prospective, observational, non-randomized, single-centre study comparing Dexcom G6® CBG level monitoring with the standard methods routinely used in this context. The standard blood glucose values were paired to the time corresponding values measured with Dexcom G6®. Agreement between the two methods and potential correlation in case of paracetamol use were calculated.

RESULTS

From May 2020 to August 2021, 36 out of 206 patients operated for isolated coronary artery bypass grafting were enrolled; 673 paired blood glucose level were analyzed. Global agreement (ρc) was 0.85 (95% C.I.: 0.84-0.86), intensive care unit agreement was 0.78 (95%C.I.: 0.74-0.82) and ward agreement was 0.91 (95%C.I.: 0.89-0.93). In the diabetic population, it was 0.87 (95%C.I.: 0.85-0.90). When paracetamol was used, the difference was 0.02 mmol/l (95%C.I.: 0.29-0.33).

CONCLUSIONS

Dexcom G6® provides good blood glucose level accuracy in the postoperative context of cardiac surgery compared to the standard methods of measurements. The results are particularly reliable in the ward where the need for repeated capillary glucose measurements implies patient discomfort and time-consuming manipulations for the nursing staff.

Acute Glycemic Variability and Early Outcomes After Cardiac Surgery: A Meta-Analysis

The influence of acute glycemic variability (GV) on early outcomes of patients after cardiac surgery remains not fully determined. We performed a systematic review and meta-analysis to evaluate the association between acute GV and in-hospital outcomes of patients after cardiac surgery. Relevant observational studies were obtained by search of electronic databases including Medline, Embase, Cochrane Library, and Web of Science. A randomized-effects model was selected to pool the data by incorporating the influence of potential heterogeneity. Nine cohort studies involving 16 411 patients after cardiac surgery were included in this meta-analysis. Pooled results showed that a high acute GV was associated with an increased risk of major adverse events (MAE) during hospitalization for patients after cardiac surgery [odds ratio [OR]: 1.29, 95% CI: 1.15 to 1.45, p<0.001, I22=38%]. Sensitivity analysis limited to studies of on-pump surgery and GV evaluated by coefficient of variation of blood glucose showed similar results. Subgroup analysis suggested that a high acute GV was related to an increased incidence of MAE in patients after coronary artery bypass graft, but not for those after isolated valvular surgery (p=0.04), and the association was weakened after adjustment of glycosylated hemoglobin (p=0.01). Moreover, a high acute GV was also related to an increased risk of in-hospital mortality (OR: 1.55, 95% CI: 1.15 to 2.09, p=0.004; I22=0%). A high acute GV may be associated with poor in-hospital outcomes in patients after cardiac surgery.

Dysglycemia and arrhythmias

Disorders in glucose metabolism can be divided into three separate but interrelated domains, namely hyperglycemia, hypoglycemia, and glycemic variability. Intensive glycemic control in patients with diabetes might increase the risk of hypoglycemic incidents and glucose fluctuations. These three dysglycemic states occur not only amongst patients with diabetes, but are frequently present in other clinical settings, such as during critically ill. A growing body of evidence has focused on the relationships between these dysglycemic domains with cardiac arrhythmias, including supraventricular arrhythmias (primarily atrial fibrillation), ventricular arrhythmias (malignant ventricular arrhythmias and QT interval prolongation), and bradyarrhythmias (bradycardia and heart block). Different mechanisms by which these dysglycemic states might provoke cardiac arr-hythmias have been identified in experimental studies. A customized glycemic control strategy to minimize the risk of hyperglycemia, hypoglycemia and glucose variability is of the utmost importance in order to mitigate the risk of cardiac arrhythmias.

Glycemic variability and the risk of atrial fibrillation: a meta-analysis

Background

Glycemic variability (GV) has been associated with vascular complications in patients with diabetes. However, the relationship between GV and risk of atrial fibrillation (AF) remains not fully determined. We therefore conducted a systematic review and meta-analysis to evaluate the above association.

Methods

Medline, Embase, Web of Science, Wanfang, and China National Knowledge Infrastructure were searched for longitudinal follow-up studies comparing the incidence of AF between patients with higher versus lower GV. A random-effects model incorporating the potential heterogeneity was used to pool the results.

Results

Nine cohort studies with 6,877,661 participants were included, and 36,784 (0.53%) participants developed AF during follow-up. Pooled results showed that a high GV was associated with an increased risk of AF (risk ratio [RR]: 1.20, 95% confidence interval [CI]: 1.11 to 1.30, p < 0.001, I² = 20%). Subgroup analyses suggested consistent association between GV and AF in prospective (RR: 1.29, 95% CI: 1.05 to 1.59, p = 0.01) and retrospective studies (RR: 1.18, 95% CI: 1.08 to 1.29, p = 0.002), in diabetic (RR: 1.24, 95% CI: 1.03 to 1.50, p = 0.03) and non-diabetic subjects (RR: 1.13, 95% CI: 1.00 to 1.28, p = 0.05), in studies with short-term (RR: 1.25, 95% CI: 1.11 to 1.40, p < 0.001) and long-term GV (RR: 1.18, 95% CI: 1.05 to 1.34, p = 0.006), and in studies with different quality scores (p for subgroup difference all > 0.05).

Conclusion

A high GV may predict an increased risk of AF in adult population.

Association between Variability of Metabolic Risk Factors and Cardiometabolic Outcomes

Despite strenuous efforts to reduce cardiovascular disease (CVD) risk by improving cardiometabolic risk factors, such as glucose and cholesterol levels, and blood pressure, there is still residual risk even in patients reaching treatment targets. Recently, researchers have begun to focus on the variability of metabolic variables to remove residual risks. Several clinical trials and cohort studies have reported a relationship between the variability of metabolic parameters and CVDs. Herein, we review the literature regarding the effect of metabolic factor variability and CVD risk, and describe possible mechanisms and potential treatment perspectives for reducing cardiometabolic risk factor variability.

The Role of Glycemic Variability in Cardiovascular Disorders

Diabetes mellitus (DM) is one of the most common and costly disorders that affect humans around the world. Recently, clinicians and scientists have focused their studies on the effects of glycemic variability (GV), which is especially associated with cardiovascular diseases. In healthy subjects, glycemia is a very stable parameter, while in poorly controlled DM patients, it oscillates greatly throughout the day and between days. Clinically, GV could be measured by different parameters, but there are no guidelines on standardized assessment. Nonetheless, DM patients with high GV experience worse cardiovascular disease outcomes. In vitro and in vivo studies showed that high GV causes several detrimental effects, such as increased oxidative stress, inflammation, and apoptosis linked to endothelial dysfunction. However, the evidence that treating GV is beneficial is still scanty. Clinical trials aiming to improve the diagnostic and prognostic accuracy of GV measurements correlated with cardiovascular outcomes are needed. The present review aims to evaluate the clinical link between high GV and cardiovascular diseases, taking into account the underlined biological mechanisms. A clear view of this challenge may be useful to standardize the clinical evaluation and to better identify treatments and strategies to counteract this DM aspect.

The effect of dexmedetomidine on intraoperative blood glucose homeostasis: secondary analysis of a randomized controlled trial

Purpose

To investigate the effect of dexmedetomidine on intraoperative blood glucose hemostasis in elderly patients undergoing non-cardiac major surgery.

Methods

This was secondary analysis of a randomized controlled trial. Patients in dexmedetomidine group received a loading dose dexmedetomidine (0.6 μg/kg in 10 min before anaesthesia induction) followed by a continuous infusion (0.5 μg/kg/hr) till 1 h before the end of surgery. Patients in control group received volume-matched normal saline at the same time interval. Primary outcome was the incidence of intraoperative hyperglycemia (blood glucose higher than 10 mmol/L).

Results

303 patients in dexmedetomidine group and 306 patients in control group were analysed. The incidence of intraoperative hyperglycemia showed no statistical significance between dexmedetomidine group and control group (27.4% vs. 22.5%, RR = 1.22, 95%CI 0.92–1.60, P = 0.167). Median value of glycemic variation in dexmedetomidine group (2.5, IQR 1.4–3.7, mmol) was slightly lower than that in control group (2.6, IQR 1.5–4.0, mmol), P = 0.034. In multivariable logistic analysis, history of diabetes (OR 3.007, 95%CI 1.826–4.950, P < 0.001), higher baseline blood glucose (OR 1.353, 95%CI 1.174–1.560, P < 0.001) and prolonged surgery time (OR 1.197, 95%CI 1.083–1.324, P < 0.001) were independent risk factors of hyperglycaemia.

Conclusions

Dexmedetomidine presented no effect on intraoperative hyperglycemia in elderly patients undergoing major non-cardiac surgery.

Trial registration

Present study was registered at Chinese Clinical Trial Registry on December 1, 2015 (www.chictr.org.cn, registration number ChiCTR-IPR-15007654).