Relationships Between Glycemic Control and Cardiovascular Fitness

Cardiorespiratory dynamics of type 2 diabetes mellitus: An extensive view of breathing and fitness challenges in a diabetes prevalent population

BACKGROUND

Diabetes mellitus (DM) is well known for related micro and macrovascular complications. Uncontrolled hyperglycemia in diabetes mellitus leads to endothelial dysfunction, inflammation, microvascular impairment, myocardial dysfunction, and skeletal muscle changes which affect multiple organ systems. This study was designed to take an extensive view of cardiorespiratory dynamics in patients with type 2 DM.

METHODS

One hundred healthy controls (HC) and 100 DM patients were enrolled. We measured and compared the breathing patterns (spirometry), VO2 max levels (heart rate ratio method) and self-reported fitness level (international fitness scale) of individuals with and without diabetes. Data was analyzed in SPSS v.22 and GraphPad Prism v8.0.

RESULTS

We observed restrictive spirometry patterns (FVC <80%) in 22% of DM as compared to 2% in HC (p = 0.021). There was low mean VO2 max in DM as compared to HC(32.03 ± 5.36 vs 41.91 ± 7.98 ml/kg/min; p value <0.001). When evaluating physical fitness on self-reported IFiS scale, 90% of the HC report average, good, or very good fitness levels. In contrast, only 45% of the DM shared this pattern, with a 53% proportion perceiving their fitness as poor or very poor (p = <0.05). Restrictive respiratory pattern, low VO2 max and fitness level were significantly associated with HbA1c and long-standing DM.

CONCLUSION

This study shows decreased pulmonary functions, decreased cardiorespiratory fitness (VO2 max) and IFiS scale variables in diabetic population as compared to healthy controls which are also associated with glycemic levels and long-standing DM. Screening for pulmonary functions can aid optimum management in this population.

Effects of acute aerobic exercise on circulating sTLR and sRAGE profiles in normal- and abnormal-glucose-tolerant individuals

BMI-matched normal- (NGT, n = 10, 41 ± 4y, 35.6 ± 3.0 kg/m2 ) and abnormal-glucose-tolerant (AGT, n = 16, 51 ± 3y, 34.3 ± 1.5 kg/m2 ) participants were evaluated for body composition, metabolic health (oral glucose tolerance test [OGTT]), and VO2 max. Participants also completed a treadmill walking test at 65% VO2 max for 30 min. Total sRAGE, esRAGE, sTLR2, and sTLR4 were assessed via ELISA, and cRAGE was calculated. AGT exhibited greater (p < 0.05) body fat % (+24%), fasting plasma glucose (+37%), OGTT AUC (+59%), and HOMA-IR (+55%) and lower (p < 0.05) VO2 max (-24%). sTLR2 was 33% lower in AGT than NGT (main effect, p = 0.034). However, sTLR2 did not change (p > 0.05) following AE. sTLR4 tended to be 36% lower in AGT than NGT (main effect, p = 0.096) and did not change following AE (p > 0.05). Total sRAGE and isoforms were similar (p > 0.05) between groups and did not change following AE (p > 0.05). sTLR2 was correlated with (p < 0.05) basal BG (r = -0.505) and OGTT AUC (r = -0.687). sTLR4 was correlated with basal BG (p < 0.10, r = -0.374) and OGTT AUC (p < 0.05, r = -0.402). Linear regressions were predictive of sTLRs in the basal state (sTLR2: R2  = 0.641, p = 0.01; sTLR4: R2  = 0.566, p = 0.037) and after acute exercise state (sTLR2: R2  = 0.681, p = 0.004, sTLR4: R2  = 0.568, p = 0.036).These findings show circulating sTLR profiles are disrupted in AGT and acute AE minimally modulates their levels.

Effectiveness of high intensity interval training on cardiorespiratory fitness and endothelial function in type 2 diabetes: A systematic review

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a chronic metabolic syndrome characterized by insulin resistance and hyperglycemia that may lead to endothelial dysfunction, reduced functional capacity and exercise intolerance. Regular aerobic exercise has been promoted as the most beneficial non-pharmacological treatment of cardiovascular diseases. High intensity interval training (HIIT) seems to be superior than moderate-intensity continuous training (MICT) in cardiovascular diseases by improving brachial artery flow-mediated dilation (FMD) and cardiorespiratory fitness to a greater extent. However, the beneficial effects of HIIT in patients with T2DM still remain under investigation and number of studies is limited.

AIM

To evaluate the effectiveness of high intensity interval training on cardiorespiratory fitness and endothelial function in patients with T2DM.

METHODS

We performed a search on PubMed, PEDro and CINAHL databases, selecting papers published between December 2012 and December 2022 and identified published randomized controlled trials (RCTs) in the English language that included community or outpatient exercise training programs in patients with T2DM. RCTs were assessed for methodological rigor and risk of bias via the Physiotherapy Evidence Database (PEDro). The primary outcome was peak VO₂ and the secondary outcome was endothelial function assessed either by FMD or other indices of microcirculation.

RESULTS

Twelve studies were included in our systematic review. The 12 RCTs resulted in 661 participants in total. HIIT was performed in 310 patients (46.8%), MICT to 271 and the rest 80 belonged to the control group. Peak VO₂ increased in 10 out of 12 studies after HIIT. Ten studies compared HIIT with other exercise regimens (MICT or strength endurance) and 4 of them demonstrated additional beneficial effects of HIIT over MICT or other exercise regimens. Moreover, 4 studies explored the effects of HIIT on endothelial function and FMD in T2DM patients. In 2 of them, HIIT further improved endothelial function compared to MICT and/or the control group while in the rest 2 studies no differences between HIIT and MICT were observed.

CONCLUSION

Regular aerobic exercise training has beneficial effects on cardiorespiratory fitness and endothelial function in T2DM patients. HIIT may be superior by improving these parameters to a greater extent than MICT.

Prevalence of disordered eating in adults with type 1 diabetes in an Australian metropolitan hospital

The purpose of this study is to establish the prevalence of disordered eating behaviours and establish its identifiable factors in adults with T1D attending a large tertiary hospital service. In this cross-sectional study, 199 participants with TID, aged 18-65 years, completed the revised Diabetes Eating Problem Survey-Revised (DEPS-R). Additional demographic and medical data obtained included age, sex, BMI, HbA1C, duration of diabetes and number of hospital admissions within 12 months (including diabetic ketoacidosis). A DEPS-R score of ≥20, indicative of disordered eating behaviour, was evident in 31% of participants. A DEPS-R score of ≥20 was associated with being female (39% females vs. 23.3% males; p = .016) and a high HbA1c (8.9% [7.8-10.2] vs. 8.0% [7.3-8.7], median [IQR], p < .001). The prevalence of disordered eating behaviours increased significantly with BMI, from 21.3% in the healthy BMI group (18.5-24.9 kg/m² ) to 37.1% in the group with BMI > 25 kg/m² (p = .02). A DEPS-R score of ≥20 was often driven by questions related to a desire to lose weight, meal patterns and glycaemic control. While these behaviours may be attributed to desirable self-management behaviours for adults with T1D, the DEPS-R is still a useful tool to identify patients with potential disordered eating behaviours and the need for dietetic intervention.

Type 2 diabetes and reduced exercise tolerance: a review of the literature through an integrated physiology approach

The association between type 2 diabetes mellitus (T2DM) and heart failure (HF) is well established. Early in the course of the diabetic disease, some degree of impaired exercise capacity (a powerful marker of health status with prognostic value) can be frequently highlighted in otherwise asymptomatic T2DM subjects. However, the literature is quite heterogeneous, and the underlying pathophysiologic mechanisms are far from clear. Imaging-cardiopulmonary exercise testing (CPET) is a non-invasive, provocative test providing a multi-variable assessment of pulmonary, cardiovascular, muscular, and cellular oxidative systems during exercise, capable of offering unique integrated pathophysiological information. With this review we aimed at defying the cardiorespiratory alterations revealed through imaging-CPET that appear specific of T2DM subjects without overt cardiovascular or pulmonary disease. In synthesis, there is compelling evidence indicating a reduction of peak workload, peak oxygen assumption, oxygen pulse, as well as ventilatory efficiency. On the contrary, evidence remains inconclusive about reduced peripheral oxygen extraction, impaired heart rate adjustment, and lower anaerobic threshold, compared to non-diabetic subjects. Based on the multiparametric evaluation provided by imaging-CPET, a dissection and a hierarchy of the underlying mechanisms can be obtained. Here we propose four possible integrated pathophysiological mechanisms, namely myocardiogenic, myogenic, vasculogenic and neurogenic. While each hypothesis alone can potentially explain the majority of the CPET alterations observed, seemingly different combinations exist in any given subject. Finally, a discussion on the effects -and on the physiological mechanisms-of physical activity and exercise training on oxygen uptake in T2DM subjects is also offered. The understanding of the early alterations in the cardiopulmonary response that are specific of T2DM would allow the early identification of those at a higher risk of developing HF and possibly help to understand the pathophysiological link between T2DM and HF.

Cardiorespiratory Performance and Acute Effect of High-intensity Exercise on Lipid Profile in Hypertensive Sedentary Older Adults with and without Diabetes Mellitus

PURPOSE

The aim of this study was to verify if the association of hypertension and diabetes mellitus could lead to the differences on cardiorespiratory fitness and lipid profile in older adults.

METHODS

40 older adults were divided into two groups: Hypertensive (HTN) and Hypertensive-diabetic (HTN + T2DM). Maximum exercise test on a treadmill was conducted. Lipid profiles assessment was conducted before and after exercise. The cardiorespiratory fitness (CRF) variables were peak oxygen consumption (VO_2peak), time to reach peak oxygen consumption (TVO_2peak), carbon dioxide ventilatory equivalent (VE/VCO₂) and carbon dioxide production (VCO₂). To test intergroup and intragroup analyses independent and paired t-tests were used before and after acute exercise. Multiple linear regression was performed to test the influence of coexistence of HTN and T2DM on CRF.

RESULTS

CRF measures such as VO_2peak (β = -3.90), VCO₂ (β = -3.87) and TVO_2peak (β= -115.79) were significantly (p-value <0.01) lower in HTN + T2DM group. After acute exercise, there was an increase in the levels of lipid profile variables, however without differences between groups.

CONCLUSION

HTN + T2DM older adults had poorer CRF. Acute changes in lipemia were similar in both groups.

Exercise Intensities as Factors of Metabolic Outcomes in Type 2 Diabetes: A Systematic Review

Exercise is effective to prevent and treat type 2 diabetes, although currently underutilized. This review analyzes the metabolic response to exercise performance at various intensities in individuals with type 2 diabetes. These findings provide insight into the development of safe and efficacious exercise prescriptions and education. We conducted a systemic review of the literature to examine the association of various exercise protocols with metabolic outcomes in type 2 diabetes. Between 1984 and 2018, 29 studies were categorized per exercise mode and intensity levels according to the American College of Sports Medicine standards. The most consistent improvement was found in HbA1c following moderate- to high-intensity exercise—post-exercise fasting glucose improved to a lesser extent. Low-intensity exercise improved HOMA-IR (homeostasis model assessment for insulin resistance) levels. Glucose and HbA1c improved most following interval compared with continuous exercise, irrespective of intensity. A comparison of high-intensity exercise with moderate-intensity exercise demonstrated few differences in HbA1c, fasting glucose, fasting insulin, and HOMA-IR. Irrespective of exercise intensity, HbA1c improvements were observed, suggesting a delayed progression to diabetes-related complications. Initial low-intensity exercise, with increased quantities when feasible, will contribute to metabolic improvements. The variability in methodology and measurement contributed to inconsistent outcomes; additional research with larger samples sizes is warranted.