Association between functional capacity and heart rate variability in patients with uncomplicated type 2 diabetes

Cardiorespiratory coupling is associated with exercise capacity in athletes: A cross-sectional study

PURPOSE

To determine the association between exercise capacity based on peak oxygen uptake (VO2peak) and resting cardiorespiratory coupling (CRC) levels in athletes and non-athletes' subjects.

METHODS

A cross-sectional study was carried out in 42 apparently healthy male subjects, aged between 20 and 40 years old. The participants were allocated into athletes (n = 21) and non-athletes (n = 21) groups. Resting electrocardiogram and respiratory movement (RESP) were simultaneously acquired during 15 min in supine position and quiet breathing. The beat-to-beat heart period (HP) and RESP series were determined from the recorded signals. Traditional analysis of HP based on frequency domain indexes was performed considering the high-frequency (0.15 - 0.45 Hz) components. To compute the CRC, the linear association between HP and RESP series was determined via squared coherence function and directionality of interaction was investigated through the causal extension of this approach. The exercise capacity was assessed through incremental cardiopulmonary exercise testing in order to determine the VO2peak.

RESULTS

Traditional analysis of HP based on high-frequency index was not correlated with exercise capacity in the athletes (r = -0.1, p = 0.5) and non-athletes (r = -0.1, p = 0.3) cohorts. However, resting CRC values was associated with exercise capacity in athletes (r = 0.4, p = 0.03), but not in the non-athletes group (r = -0.2, p = 0.3).

CONCLUSION

These results suggest that improved resting values of CRC is associated with higher exercise capacity (VO2peak) in endurance athletes. Moreover, frequency domain of HP was not sensitive to identifying this relationship, probably because effects of training on parasympathetic modulation might be affected by respiratory dynamics, and this influence has a directionality (i.e., from RESP to HP).

Cardiorespiratory fitness in individuals with type 2 diabetes mellitus: a systematic review and meta-analysis

Objective

To conduct a systematic review and meta-analysis assessing the cardiorespiratory fitness (CRF) among individuals with and without type 2 diabetes.

Materials and methods

The current review was registered in PROSPERO under the number CRD42018082718. MEDLINE, EMBASE, and Cochrane Library databases were searched from inception through February 2022. Eligibility criteria consisted of observational or interventional studies that evaluated CRF through cardiopulmonary exercise testing or six-minute walk test in individuals with type 2 diabetes compared with individuals without type 2 diabetes. For data extraction, we used baseline CRF assessments of randomized clinical trials or follow-up CRF assessments in observational studies. We performed a meta-analysis using maximal oxygen consumption (VO2 max), and distance walked in the 6MWT as primary outcomes. They were extracted and expressed as mean differences (MDs) and 95% CIs between treatment and comparator groups. The meta-analysis was conducted using Review Manager (RevMan) software.

Results

Out of 8,347 studies retrieved, 77 were included. Compared with individuals without type 2 diabetes, individuals with diabetes achieved a lower VO2 max (-5.84 mL.kg-1.min-1, 95% CI -6.93, -4.76 mL.kg-1.min-1, p = <0.0001; I2 = 91%, p for heterogeneity < 0.0001), and a smaller distance walked in 6MWT (-93.30 meters, 95% CI -141.2, -45.4 meters, p > 0.0001; I2: 94%, p for heterogeneity < 0.0001).

Conclusion

Type 2 diabetes was associated with lower cardiorespiratory fitness, as observed by lower VO2 max on maximal tests, and smaller distance walked in 6MWT, however the quality of studies was low.

Association of depression and parasympathetic activation with glycemic control in type 2 diabetes mellitus

AIM

Patients with type 2 diabetes mellitus exhibited autonomic nervous system (ANS) dysfunction and comorbidities with depressive or anxiety symptoms were related to poor glycemic control. Heart rate variability (HRV) converted from electrocardiogram (ECG) has been used as the ANS index. The study aimed to explore the associations between depression, anxiety, HRV, and glycemic control in patients with type 2 diabetes mellitus.

METHODS

The Patient Health Questionnaire-9 (PHQ-9) and Generalized Anxiety Disorder-7 (GAD-7) questionnaires were used to assess depressive and anxiety symptoms in 647 patients with type 2 diabetes mellitus (mean age was 63 ± 10 years, 56 % males). The ECG raw signals were collected from a 5-min sitting and resting baseline and then transformed to HRV indices referring ANS activation. Blood glucose and lipid profiles including glycated hemoglobin (HbA1c), high-density lipoprotein (HDL), low-density lipoprotein (LDL), and triglyceride were obtained from the electronic medical records.

RESULTS

Ninety-nine (15 %) participants had depressive symptoms and 59 (9 %) had anxiety symptoms. Depression and HbA1c were negatively correlated with parasympathetic activation. Depression and anxiety were positively correlated with sympathetic activation. After controlling for demographic data and lipid profiles, depression was a significant positive predictor for HbA1c levels; and HRV indices (lnLF and lnHF) were the significant negative predictors for HbA1c levels. Mediation effect analysis showed that depression was a mediator between parasympathetic activation and glycemic control.

CONCLUSIONS

Lower parasympathetic activation and higher depressive symptoms may affect glycemic control in patients with type 2 diabetes mellitus. Intervention programs targeting to increase parasympathetic activities and reducing depression could be further tested for their effects on glycemic outcomes for potential clinical use.

Type II diabetes accentuates diaphragm blood flow increases during submaximal exercise in the rat

We investigated the effect of type 2 diabetes mellitus (T2DM) on respiratory muscle blood flow (BF) during exercise. Using the Goto-Kakizaki (GK) rat model of T2DM, we hypothesized that diaphragm, intercostal and transverse abdominis BFs (radiolabeled microspheres) would be higher in male GK rats (n = 10) compared to healthy male Wistar controls (CON; n = 8) during submaximal exercise (20 m/min, 10 % grade). Blood glucose was significantly higher in GK (246 ± 29 mg/dL) compared to CON (103 ± 4 mg/dL; P < 0.01). Respiratory muscle BFs were not different at rest (P> 0.50). From rest to submaximal exercise, respiratory muscle BFs increased in both groups to all muscles (P < 0.01). During submaximal exercise GK rats had higher diaphragm BFs (GK: 189 ± 13; CON: 138 ± 14 mL/min/100 g, P < 0.01), and vascular conductance (GK: 1.4 ± 0.1; CON: 1.0 ± 0.1 mL/min/mmHg/100 g; P < 0.01) compared to CON. There were no differences in intercostal or transverse abdominis BF or VC during exercise (P> 0.15). These findings suggest that submaximal exercise requires a higher diaphragm BF and VC in T2DM compared to healthy counterparts.

Clinical outcomes after cardiac rehabilitation in elderly patients with and without diabetes mellitus: The EU-CaRE multicenter cohort study

Background

The prevalence of patients with concomitant cardiovascular disease and diabetes mellitus (DM) is increasing rapidly. We aimed to compare the effectiveness of current cardiac rehabilitation (CR) programs across seven European countries between elderly cardiac patients with and without DM.

Methods

1633 acute and chronic coronary artery disease (CAD) patients and patients after valve intervention with an age 65 or above who participated in comprehensive CR (3 weeks to 3 months, depending on centre) were included. Peak oxygen uptake (VO₂ peak), body mass index, resting systolic blood pressure, low-density lipoprotein-cholesterol (LDL-C), and glycated haemoglobin (HbA1c) were assessed before start of CR, at termination of CR (variable time point), and 12 months after start of CR, with no intervention after CR. Baseline values and changes from baseline to 12-month follow-up were compared between patients with and without DM using mixed models, and mortality and hospitalisation rates using logistic regression.

Results

430 (26.3%) patients had DM. Patients with DM had more body fat, lower educational level, more comorbidities, cardiovascular risk factors, and more advanced CAD. Both groups increased their VO₂ peak over the study period but with a significantly lower improvement from baseline to follow-up in patients with DM. In the DM group, change in HbA1c was associated with weight change but not with change in absolute VO₂ peak. 12-month cardiac mortality was higher in patients with DM.

Conclusions

While immediate improvements in VO₂ peak after CR in elderly patients with and without DM were similar, 12-month maintenance of this improvement was inferior in patients with DM, possibly related to disease progression. Glycemic control was less favourable in diabetic patients needing insulin in the short- and long-term. Since glycemic control was only related to weight loss but not to increase in exercise capacity, this highlights the importance of weight loss in obese DM patients during CR.

Trial registration NTR5306 at trialregister.nl; trial registered 07/16/2015; https://www.trialregister.nl/trial/5166