Coefficient of variation of R-R interval closely correlates with glycemic variability assessed by continuous glucose monitoring in insulin-depleted patients with type 1 diabetes

Associations of age-adjusted coefficient of variation of R-R intervals with autonomic and peripheral nerve function in non-elderly persons with diabetes

AIMS/INTRODUCTION

Early diagnosis of diabetes-associated cardiac autonomic neuropathy using the coefficient of variation of R-R intervals (CVRR) may improve outcomes for individuals with diabetes. The present study examined the associations of decreased CVRR at rest and during deep breathing (DB) with other autonomic nerve function parameters.

MATERIALS AND METHODS

The electronic records of 141 inpatients with diabetes (22-65 years) admitted to our hospital between March 2015 and March 2019 were analyzed retrospectively. After assessment by exclusion criteria, 51 inpatients were included. All inpatients were assessed for peripheral and autonomic nerve function, clinical characteristics, and physical abilities.

RESULTS

Inpatients with decreased CVRR at rest (n = 9 (17.6%)) and during DB (n = 12 (23.5%)) had a longer duration of known diabetes, a higher prevalence of diabetic retinopathy, lower body mass index (BMI), skeletal mass index (SMI), and knee extension strength, and a higher proportion of impaired standing balance. Decreased CVRR at rest was associated with a greater fall in diastolic BP from supine to standing, higher resting HR, longer QTc, longer time of voiding, and sensory symptoms.

CONCLUSIONS

Decreased CVRR at rest and during deep breathing was associated with lower BMI, SMI, and knee strength and a higher proportion of impaired standing balance among non-elderly inpatients with diabetes. Decreased CVRR at rest appeared more strongly associated with a greater orthostatic BP decline, higher resting heart rate, longer QTc, lower urinary tract dysfunction, and sensory symptoms than a decreased CVRR during deep breathing.

Coefficient of R-R interval variations under deep breathing load in patients with wild-type transthyretin amyloid cardiomyopathy: A case-control study

BACKGROUND AND AIMS

An autonomic nervous disorder is an important characteristic of cardiac amyloidosis; however, the prevalence of autonomic dysfunction in wild-type transthyretin amyloidosis (ATTRwt) has not been established. Analysis of the R-R interval coefficient of variation (CVR-R) is a noninvasive method to measure parasympathetic activity. We aimed to assess autonomic dysfunction of ATTRwt and determine the utility of CVR-R for the detection of ATTRwt in other cardiac diseases.

METHODS

This is a single-center, retrospective, case-control study. Fifty patients with heart failure (HF) were studied. The etiologies of HF were as follows: ATTRwt, n = 10; previous myocardial infarction (MI), n = 20; and left ventricular hypertrophy (LVH) due to other disease processes (e.g., aortic stenosis), n = 20. We measured the CVR-R at rest (CVR-Rrest), CVR-R with deep breaths (CVR-Rbreath), and the change rate (CVR-Rdiff rate). The relative change formula is as follows: CVR-Rdiff rate = (CVR-Rbreath - CVR-Rrest)/CVR-Rrest×  100 (%).

RESULTS

There was no difference in the CVR-Rrest levels among the three groups. The CVR-Rdiff rate levels in the ATTRwt group were significantly lower (ATTRwt: -8.77 [-43.8 to 10.9]; LVH: 67.4 [38.7 to 89.4]; MI: 83.7 [60.4 to 142.9]). Based on the receiver operative characteristic curve analysis to identify ATTRwt in HF, the best cut-off value for the CVR-Rdiff rate was 19.7 (area under the curve: 0.848).

CONCLUSION

Our data suggested autonomic dysfunction in patients with ATTRwt. Measurement of the CVR-R in HF patients may be a convenient support tool for the detection of ATTRwt.

Long-term complications of type 1 diabetes: what do we know and what do we need to understand?

Long-term complications of type 1 diabetes (T1D) include microvascular complications and macrovascular disease. Despite the important advances in the treatment of T1D of the last decades, these complications still represent the leading cause of morbidity and mortality in patients with T1D. Extensive evidence indicates that structural and functional alterations of the kidney, retina, nerves and large arteries occur already in the first years after the onset of diabetes. We performed a comprehensive review of the available evidence on screening, diagnosis, prevention and treatment of vascular complications of T1D. In particular, we focused on three major challenges related to long-term complications of T1D: 1) finding of new biomarkers and diagnostic methods able to identify early signs of complications; 2) identifying specific risk factors for the development of these complications; 3) identifying and implementing new therapeutic strategies able to prevent the development and progression of vascular complications.

Characteristics, Management, and Outcomes of Elderly Patients with Diabetes in a Covid-19 Unit: Lessons Learned from a Pilot Study

Background and objectives: Diabetes may affect in-hospital mortality of patients with Coronavirus disease 2019 (COVID-19). We have retrospectively evaluated clinical characteristics, diabetes management, and outcomes in a sample of COVID-19 patients with diabetes admitted to our hospital. Materials and Methods: All patients admitted to the Infectious Diseases Unit from 28 March 2020, to 16 June 2020, were enrolled. Clinical information and biochemical parameters were collected at the time of admission. Patients were ranked according to diabetes and death. Results: Sixty-one patients with COVID-19 were analyzed. Most of them were from a long-term health care facility. Mean age was 77 ± 16 years, and 19 had type 2 diabetes (T2D). Eighteen patients died, including 8 with T2D and 10 without T2D (p = 0.15). Patients with diabetes were significantly older, had a higher prevalence of cardiovascular diseases, and a significantly lower lymphocyte count. No significant relationship was found between diabetes and in-hospital mortality (Odds Ratio OR 2.3; Confidence Interval CI 0.73–7.38, p = 0.15). Patients with diabetes were treated with insulin titration algorithm. Severe hypoglycemic events, ketoacidosis and hyperosmolar hyperglycemias did not occur during hospitalization. Mean pre-meal capillary blood glucose was 157 ± 45 mg/dL, and the coefficient of variation of glycaemia was 29%. Conclusions: Our study, albeit limited by the small number of subjects, did not describe any significant association between T2D diabetes and mortality. Clinical characteristics of patients, and acceptable glucose control prior and during hospitalization may have influenced the result. The use of an insulin titration algorithm should be pursued during hospitalization.

The relationship between glycaemic variability and cardiovascular autonomic dysfunction in patients with type 1 diabetes: A systematic review

Rigorous glycaemic control-reflected by low HbA1c goals-is of the utmost importance in the prevention and management of complications in patients with type 1 diabetes mellitus (T1DM). However, previous studies suggested that short-term glycaemic variability (GV) is also important to consider as excessive glucose fluctuations may have an additional impact on the development of diabetic complications. The potential relationship between GV and the risk of cardiovascular autonomic neuropathy (CAN), a clinical expression of cardiovascular autonomic dysfunction, is of increasing interest. This systematic review aimed to summarize existing evidence concerning the relationship between GV and cardiovascular autonomic dysfunction in T1DM. An electronic database search of Medline (PubMed), Web of Science and Embase was performed up to October 2019. There were no limits concerning year of publication. Methodological quality was evaluated using the Newcastle Ottawa Scale for observational studies. Six studies (four cross-sectional and two prospective cohorts) were included. Methodological quality of the studies varied from level C to A2. Two studies examined the association between GV and heart rate variability (HRV), and both found significant negative correlations. Regarding cardiovascular autonomic reflex tests (CARTs), two studies did not, while two other studies did find significant associations between GV parameters and CART scores. However, associations were attenuated after adjusting for covariates such as HbA1c, age and disease duration. In conclusion, this systematic review found some preliminary evidence supporting an association between GV and cardiovascular autonomic dysfunction in T1DM. Hence, uncertainty remains whether high GV can independently contribute to the onset or progression of CAN. The heterogeneity in the methodological approach made it difficult to compare different studies. Future studies should therefore use uniformly evaluated continuous glucose monitoring-derived parameters of GV, while standardized assessment of HRV, CARTs and other potential cardiac autonomic function parameters is needed for an unambiguous definition of CAN.

Glycaemic variability: The under-recognized therapeutic target in type 1 diabetes care

Type 1 diabetes mellitus (T1DM) remains one of the most challenging long-term conditions to manage. Despite robust evidence to demonstrate that near normoglycaemia minimizes, but does not completely eliminate, the risk of complications, its achievement has proved almost impossible in a real-world setting. HbA1c to date has been used as the gold standard marker of glucose control and has been shown to reflect directly the risk of diabetes complications. However, it has been recognized that HbA1c is a crude marker of glucose control. Continuous glucose monitoring (CGM) provides the ability to measure and observe inter- and intraday glycaemic variability (GV), a more meaningful measure of glycaemic control, more relevant to daily living for those with T1DM. This paper reviews the relationship between GV and hypoglycaemia, and micro- and macrovascular complications. It also explores the impact on GV of CGM, insulin pumps, closed-loop technologies, and newer insulins and adjunctive therapies. Looking to the future, there is an argument that GV should become a key determinant of therapeutic success. Further studies are required to investigate the pathological and psychological benefits of reducing GV.

Molecular Mechanisms of Glucose Fluctuations on Diabetic Complications

Accumulating evidence indicates the occurrence and development of diabetic complications relates to not only constant high plasma glucose, but also glucose fluctuations which affect various kinds of molecular mechanisms in various target cells and tissues. In this review, we detail reactive oxygen species and their potentially damaging effects upon glucose fluctuations and resultant downstream regulation of protein signaling pathways, including protein kinase C, protein kinase B, nuclear factor-κB, and the mitogen-activated protein kinase signaling pathway. A deeper understanding of glucose-fluctuation-related molecular mechanisms in the development of diabetic complications may enable more potential target therapies in future.

A review of personalized blood glucose prediction strategies for T1DM patients

This paper presents a methodological review of models for predicting blood glucose (BG) concentration, risks and BG events. The surveyed models are classified into three categories, and they are presented in summary tables containing the most relevant data regarding the experimental setup for fitting and testing each model as well as the input signals and the performance metrics. Each category exhibits trends that are presented and discussed. This document aims to be a compact guide to determine the modeling options that are currently being exploited for personalized BG prediction.

Diabetic Neuropathy Evaluated by a Novel Device: Sural Nerve Conduction Is Associated with Glycemic Control and Ankle-Brachial Pressure Index in Japanese Patients with Diabetes

BACKGROUND

Currently, no international diagnostic criteria for diabetic neuropathy (DN) have been established. Recently, a novel point-of-care sural nerve conduction device has been developed. We aimed to investigate associations between DN and clinical parameters related to the development and progression of DN by using this novel device.

METHODS

We conducted a retrospective observational study in patients with diabetes whose sural nerve functions were measured using DPN Check between January 2015 and October 2016. Multiple and logistic regression analyses were conducted to assess the associations of sural nerve conduction velocity (SNCV) and amplitude (SNAP) with clinical parameters related to DN.

RESULTS

A total of 740 patients were enrolled in this study. At baseline, 211 patients were diagnosed with DN by using DPN Check. The sensitivity, specificity, and positive likelihood ratio of DPN Check compared with ankle reflex as reference were 81%, 46%, and 1.5, respectively. Of these, 182 patients were followed up for approximately 1 year to measure changes in SNCV and SNAP. Both SNCV and SNAP were inversely associated with duration of diabetes, plasma glucose levels, and hemoglobin A1c levels at baseline, whereas these were positively associated with ankle-brachial index. Logistic regression analysis revealed that poor glycemic control was associated with increased risk of reduction in both SNCV [odds ratio = 1.570; 95% confidence interval (CI) = 1.298-1.898; p < 0.001] and SNAP (odds ratio = 1.408; 95% CI = 1.143-1.735; p = 0.001), and longer duration of diabetes was also significantly associated with an increased risk of reduction in both SNCV (odds ratio = 1.058; 95% CI = 1.032-1.084; p < 0.001) and SNAP (odds ratio = 1.049; 95% CI = 1.019-1.079; p = 0.001).

CONCLUSION

Sural nerve functions were significantly associated with glycemic control and arteriosclerosis in patients with diabetes. DPN Check may be useful as a screening tool to identify DN in clinical practice.

Glucose variability, HbA1c and microvascular complications

Microvascular complications in diabetes are associated with poor long-term diabetes control as measured by HbA1c levels. Glucose fluctuations are related to oxidative stress, endothelial dysfunction, and inflammation, factors traditionally associated with the pathogenesis of vascular damage. Glucose variability has been associated with macrovascular disease in some studies but any association with microvascular disease remains controversial. This overview summarizes recent findings in the field of glucose variability and its possible relationship with retinopathy, nephropathy and neuropathy. It is concluded that randomized prospective follow-up trials could possibly help estimate whether short-term glucose variability should be considered as an independent risk factor for microvascular complications in diabetes.