Associations between insulin and heart rate variability in police officers

Combining Celiac and Hepatic Vagus Nerve Neuromodulation Reverses Glucose Intolerance and Improves Glycemic Control in Pre- and Overt-Type 2 Diabetes Mellitus

Neurological disorders and type 2 diabetes mellitus (T2DM) are deeply intertwined. For example, autonomic neuropathy contributes to the development of T2DM and continued unmanaged T2DM causes further progression of nerve damage. Increasing glycemic control has been shown to prevent the onset and progression of diabetic autonomic neuropathies. Neuromodulation consisting of combined stimulation of celiac vagal fibers innervating the pancreas with concurrent electrical blockade of neuronal hepatic vagal fibers innervating the liver has been shown to increase glycemic control in animal models of T2DM. The present study demonstrated that the neuromodulation reversed glucose intolerance in alloxan-treated swine in both pre- and overt stages of T2DM. This was demonstrated by improved performance on oral glucose tolerance tests (OGTTs), as assessed by area under the curve (AUC). In prediabetic swine (fasting plasma glucose (FPG) range: 101-119 mg/dL) the median AUC decreased from 31.9 AUs (IQR = 28.6, 35.5) to 15.9 AUs (IQR = 15.1, 18.3) p = 0.004. In diabetic swine (FPG range: 133-207 mg/dL) the median AUC decreased from 54.2 AUs (IQR = 41.5, 56.6) to 16.0 AUs (IQR = 15.4, 21.5) p = 0.003. This neuromodulation technique may offer a new treatment for T2DM and reverse glycemic dysregulation at multiple states of T2DM involved in diabetic neuropathy including at its development and during progression.

Aerobic fitness influences cardiac autonomic modulation in police officers regardless of specific duties

PURPOSE

This study assesses whether the specific duties of a police officer or aerobic fitness influences blood pressure (BP) and cardiac autonomic modulation.

METHOD

Police officers (n = 161) were divided into administrative and operational (34.72 ± 5.98 vs. 33.95 ± 5.61 years old) groups, and subsequently divided into lower and higher aerobic fitness (35.49 ± 4.32 vs. 45.39 ± 13.10 mL·kg-1·min-1).

RESULTS

Higher SBP (125 ± 10 vs. 121 ± 10 mmHg; P = 0.02) and aerobic fitness (42.10 ± 5.57 vs. 38.51 ± 6.67 mL·kg-1·min-1; P < 0.01) were observed in the operational group. On the other hand, lower obesity indicators and higher heart rate variability (HRV) indices (SD1: 26.67 ± 14.19 vs. 20.98 ± 9.12; SD2: 54.04 ± 19.81 vs. 47.32 ± 18.85; RMSSD: 36.50 ± 18.78 vs. 29.90 ± 12.51; SDNN: 42.80 ± 16.05 vs. 36.85 ± 14.23 ms; pNN50: 17.32 ± 17.54 vs. 10.60 ± 10.77 %) were observed in the higher aerobic fitness group (P ≤ 0.05).

CONCLUSION

In summary, although the operational occupation had shown a negative influence on SBP, the HRV was not impaired in police officers. Additionally, aerobic fitness was related to differences in obesity indicators and HRV regardless of police duties. Our findings encourage the inclusion of BP and HRV measurements in routine health checks to screen for early hypertension and autonomic dysfunction.

Assessment of arrhythmias and cardiac autonomic tone at a relatively young age patients with obesity class III

There is no sufficient data on arrhythmias occurrence in obesity class III. The influence of hyperinsulinemia and insulin resistance on arrhythmias and cardiac autonomic tone is also of ongoing interest in these subjects. We prospectively studied 81 selected patients with body mass index >40 kg/m² , aged 34 (18-65) years. Among other examinations all subjects underwent electrocardiography and Holter monitoring with heart rate variability (HRV) and turbulence (HRT) evaluation. Controls consisted of 45 healthy, sex- and aged-matched lean volunteers. In patients median BMI was 44.5 kg/m² (40.1-58.1), benign arterial hypertension was present in 43.2% and dysglycemia in 27.2% of cases. In the group with obesity longer PR interval (P < .001) and corrected QT interval (P < .001) were observed, while in Holter monitoring no significant differences in supraventricular or ventricular arrhythmias and also bradyarrhythmias prevalence were observed in comparison to controls. In individuals with obesity HRV indices associated with sympathetic tone were significantly impaired and also abnormal HRT values (21.9 vs 0%, P = .04) were more frequently observed. There were no significant correlations between anthropometric obesity parameters and fasting insulin concentration, insulin resistance index and also HRV/HRT parameters in studied individuals. Univariate regression analysis revealed that only age influenced abnormal HRT occurrence (OR 1.69, 95%CI 1.08-2.98, P = .04). In conclusions, patients with obesity class III at a relatively young age who reported they felt healthy, do not present increased prevalence of arrhythmias, including life-threatening ones. Cardiac autonomic dysfunction is observed in these patients, however it has not been shown to be associated with anthropometric measurements.

Metformin may adversely affect orthostatic blood pressure recovery in patients with type 2 diabetes: substudy from the placebo-controlled Copenhagen Insulin and Metformin Therapy (CIMT) trial

Background

Metformin has been shown to have both neuroprotective and neurodegenerative effects. The aim of this study was to investigate the effect of metformin in combination with insulin on cardiovascular autonomic neuropathy (CAN) and distal peripheral neuropathy (DPN) in individuals with type 2 diabetes (T2DM).

Methods

The study is a sub-study of the CIMT trial, a randomized placebo-controlled trial with a 2 × 3 factorial design, where 412 patients with T2DM were randomized to 18 months of metformin or placebo in addition to open-labelled insulin. Outcomes were measures of CAN: Changes in heart rate response to deep breathing (beat-to-beat), orthostatic blood pressure (OBP) and heart rate and vibration detection threshold (VDT) as a marker DPN. Serum levels of vitamin B12 and methyl malonic acid (MMA) were analysed.

Results

After 18 months early drop in OBP (30 s after standing) was increased in the metformin group compared to placebo: systolic blood pressure drop increased by 3.4 mmHg (95% CI 0.6; 6.2, p = 0.02) and diastolic blood pressure drop increased by 1.3 mmHg (95% CI 0.3; 2.6, p = 0.045) compared to placebo. Beat-to-beat variation decreased in the metformin group by 1.1 beats per minute (95% CI − 2.4; 0.2, p = 0.10). Metformin treatment did not affect VDT group difference − 0.33 V (95% CI − 1.99; 1.33, p = 0.39) or other outcomes. Changes in B12, MMA and HbA_1c did not confound the associations.

Conclusions

Eighteen months of metformin treatment in combination with insulin compared with insulin alone increased early drop in OBP indicating an adverse effect of metformin on CAN independent of vitamin B12, MMA HbA_1c.

Trial registration The protocol was approved by the Regional Committee on Biomedical Research Ethics (H–D-2007-112), the Danish Medicines Agency and registered with ClinicalTrials.gov (NCT00657943).

Pilot Trial of a Noninvasive Closed-Loop Neurotechnology for Stress-Related Symptoms in Law Enforcement: Improvements in Self-Reported Symptoms and Autonomic Function

Background

Law enforcement officers have decreased life expectancy, attributed to work-related exposure to traumatic stress and circadian disruption. Autonomic dysregulation is reported with traumatic stress and chronic insomnia.

Objective

We explore potential benefits for reduced symptoms related to stress and insomnia and improved autonomic function associated with open label use of high-resolution, relational, resonance-based, electroencephalic mirroring (HIRREM®), in a cohort of sworn law enforcement personnel.

Methods

Closed-loop noninvasive therapies utilizing real-time monitoring offer a patient-centric approach for brain-based intervention. HIRREM® is a noninvasive, closed-loop, allostatic, neurotechnology that echoes specific brain frequencies in real time as audible tones to support self-optimization of brain rhythms. Self-report symptom inventories done before and after HIRREM included insomnia (ISI), depression (CES-D), traumatic stress (PCL-C), anxiety (GAD-7), perceived stress (PSS), and quality of life (EQ-5D). Ten-minute recordings of heart rate and blood pressure allowed analysis of baroreflex sensitivity (BRS) and heart rate variability (HRV).

Results

Fifteen participants (1 female), mean (SD) age 45.7 (5.6), received 12.2 (2.7) HIRREM sessions, over 7.9 in-office days. Data were collected at baseline, and at 22.8 (9.2), and 67.2 (14.1) days after intervention. All symptom inventories improved significantly (P < .01), with durability for 2 months after completion of the intervention. The use of HIRREM was also associated with significant increases (P < .001) in HRV measured as rMSSD and BRS measured by high-frequency alpha index. There were no serious adverse events or drop outs.

Conclusion

These pilot data provide the first report of significant symptom reductions, and associated improvement in measures of autonomic cardiovascular regulation, with the use of HIRREM in a cohort of law enforcement personnel. Randomized clinical trials are warranted.

Risk Factors Associated with Cardiac Autonomic Modulation in Obese Individuals

Obesity leads to an imbalance in the autonomic nervous system, especially in increased sympathetic modulation and decreased vagal tone, and some anthropometric, metabolic, and lifestyle variables may increase the risk of developing cardiovascular disease. Objective. To analyze the association between cardiovascular autonomic modulation and biochemical and anthropometric markers, food intake, and physical activity level in severely obese individuals. Methodology. The present study is a cutout of a randomized clinical trial "Effect of nutritional intervention and olive oil in severe obesity" (DieTBra Trial), where the baseline data were analyzed. Anthropometric data, biochemical exams, heart rate variability (HRV), accelerometry, and 24 h recall (R24H) of obese patients (body mass index BMI ≥35 kg/m2) were collected. Results. 64 obese patients were analyzed, with a mean age of 39.10 ± 7.74 years (27 to 58 years). By HRV analysis, in the frequency domain, the obese had a higher predominance of sympathetic autonomic modulation (low frequency (LF) 56.44 ± 20.31 nu) and lower parasympathetic modulation (high frequency (HF) 42.52 ± 19.18 nu). A negative association was observed between the variables Homeostasis Evaluation Model (HOMA-IR) and HF (p = 0.049). In the physical activity analysis, there was a negative association between moderate to vigorous physical activity and the sympathetic component (p = 0.043), and for sedentary time (ST), there was a negative association with HF (p = 0.049) and LF/HF (p = 0.036) and a positive association with LF (p = 0.014). For multiple linear regression, waist circumference (WC) and HOMA-IR values were negatively associated with HF (β = -0.685, p = 0.010; β = -14.989, p = 0.010; respectively). HOMA-IR (β = 0.141, p = 0.003) and the percentage of lipids ingested (β = -0.030, p = 0.043) were negatively associated with LF/HF. Conclusion. Among the cardiovascular risk variables studied, insulin resistance and central adiposity showed the greatest influence on cardiac autonomic modulation of obese, increasing the risk for cardiovascular disease.

Is the Brain a Key Player in Glucose Regulation and Development of Type 2 Diabetes?

Ever since Claude Bernards discovery in the mid 19th-century that a lesion in the floor of the third ventricle in dogs led to altered systemic glucose levels, a role of the CNS in whole-body glucose regulation has been acknowledged. However, this finding was later overshadowed by the isolation of pancreatic hormones in the 20th century. Since then, the understanding of glucose homeostasis and pathology has primarily evolved around peripheral mechanism. Due to scientific advances over these last few decades, however, increasing attention has been given to the possibility of the brain as a key player in glucose regulation and the pathogenesis of metabolic disorders such as type 2 diabetes. Studies of animals have enabled detailed neuroanatomical mapping of CNS structures involved in glucose regulation and key neuronal circuits and intracellular pathways have been identified. Furthermore, the development of neuroimaging techniques has provided methods to measure changes of activity in specific CNS regions upon diverse metabolic challenges in humans. In this narrative review, we discuss the available evidence on the topic. We conclude that there is much evidence in favor of active CNS involvement in glucose homeostasis but the relative importance of central vs. peripheral mechanisms remains to be elucidated. An increased understanding of this field may lead to new CNS-focusing pharmacologic strategies in the treatment of type 2 diabetes.

Sex differences in healthy human heart rate variability: A meta-analysis

The present meta-analysis aimed to quantify current evidence on sex differences in the autonomic control of the heart, indexed by measures of heart rate variability (HRV) in healthy human subjects. An extensive search of the literature yielded 2020 titles and abstracts, of which 172 provided sufficient reporting of sex difference in HRV. Data from 63,612 participants (31,970 females) were available for analysis. Meta-analysis yielded a total of 1154 effect size estimates (k) across 50 different measures of HRV in a cumulated total of 296,247 participants. Females showed a significantly lower mean RR interval and standard deviation of RR intervals (SDNN). The power spectral density of HRV in females is characterized by significantly less total power that contains significantly greater high- (HF) and less low-frequency (LF) power. This is further reflected by a lower LF/HF ratio. Meta-regression revealed significant effects of age, respiration control and the length of recording available for analysis. Although women showed greater mean heart rate, they showed greater vagal activity indexed by HF power of HRV. Underlying mechanisms of these findings are discussed.

Poor glycemic control impacts linear and non-linear dynamics of heart rate in DM type 2

INTRODUCTION: It is well known that type 2 diabetes mellitus (T2DM) produces cardiovascular autonomic neuropathy (CAN), which may affect the cardiac autonomic modulation. However, it is unclear whether the lack of glycemic control in T2DM without CAN could impact negatively on cardiac autonomic modulation. Objective: To evaluate the relationship between glycemic control and cardiac autonomic modulation in individuals with T2DM without CAN. Descriptive, prospective and cross sectional study.METHODS: Forty-nine patients with T2DM (51±7 years) were divided into two groups according to glycosylated hemoglobin (HbA1c): G1≤7% and G2>7.0%. Resting heart rate (HR) and RR interval (RRi) were obtained and calculated by linear (Mean iRR; Mean HR; rMSSD; STD RR; LF; HF; LF/HF, TINN and RR Tri,) and non-linear (SD1; SD2; DFα1; DFα2, Shannon entropy; ApEn; SampEn and CD) methods of heart rate variability (HRV). Insulin, HOMA-IR, fasting glucose and HbA1c were obtained by blood tests.RESULTS: G2 (HbA1c≤7%) showed lower values for the mean of iRR; STD RR; RR Tri, TINN, SD2, CD and higher mean HR when compared with G1 (HbA1c > 7%). Additionally, HbA1c correlated negatively with mean RRi (r=0.28, p=0.044); STD RR (r=0.33, p=0.017); RR Tri (r=-0.35, p=0.013), SD2 (r=-0.39, p=0.004) and positively with mean HR (r=0.28, p=0.045). Finally, fasting glucose correlated negatively with STD RR (r=-0.36, p=0.010); RR Tri (r=-0.36, p=0.010); TINN (r=-0.33, p=0.019) and SD2 (r=-0.42, p=0.002).CONCLUSION: We concluded that poor glycemic control is related to cardiac autonomic modulation indices in individuals with T2DM even if they do not present cardiovascular autonomic neuropathy.

Difference of catecholamine responses to exercise in men with trisomy 21, with or without chronotropic incompetence

OBJECTIVE

Our purpose was to analyse if catecholamine responses to exercise would be different in Down syndrome (DS) with or without chronotropic incompetence.

RESEARCH DESIGN AND METHODS

Twenty five men with DS (mean age 22.2 ± 3.2) and twenty six controls (CONT, mean age 22.5 ± 1.4) participated in the study, and are divided into 3 groups: CONT, DS with chronotropic incompetence (DS+) and DS without chronotropic incompetence (DS-). During two treadmill incremental tests, blood samples were collected for the determination of hormonal and metabolic variables.

RESULTS

Ten out of 25 DS had chronotropic incompetence whereas no CONT. At rest, compared to CONT, despite similar physical activity, DS with chronotropic incompetence had significantly higher subcutaneous fat mass (p<0.001), lower epinephrine concentration (p<0.01), and higher leptin (p<0.01) and insulin concentrations (p<0.05). At peak exercise, all DS had lower heart rate, oxygen uptake and blood lactate concentrations than controls (p<0.001). During a 'Submaximal incremental test', DS with chronotropic incompetence had lower HR and lactate values (p<0.001) compared to CONT and DS without chronotropic incompetence (p<0.01). They also had blunted epinephrine and impaired norepinephrine responses to exercise compared to DS without chronotropic incompetence and CONT (p<0.01 and p<0.05 respectively).

CONCLUSIONS

Our results indicate that catecholamine adaptations to exercise are not adequate in DS+ and are associated with exercise intolerance. Thus, this endocrine profile at rest and during exercise may limit endurance performance of DS.