"Metabolic and cardiovascular response to exercise in patients with type 1 diabetes"

Altered Cardiovascular Responses to Exercise in Type 1 Diabetes

Exaggerated cardiovascular responses to exercise increase the risk of myocardial infarction and stroke in individuals with type 1 diabetes (T1D); however, the underlying mechanisms remain largely elusive. This review provides an overview of the altered exercise pressor reflex in T1D, with an emphasis on the mechanical component of the reflex.

Association of HbA1c with VO2max in Individuals with Type 1 Diabetes: A Systematic Review and Meta-Analysis

The aim of this systematic review and meta-analysis was to evaluate the association between glycemic control (HbA1c) and functional capacity (VO2max) in individuals with type 1 diabetes (T1DM). A systematic literature search was conducted in EMBASE, PubMed, Cochrane Central Register of Controlled Trials, and ISI Web of Knowledge for publications from January 1950 until July 2020. Randomized and observational controlled trials with a minimum number of three participants were included if cardio-pulmonary exercise tests to determine VO2max and HbA1c measurement has been performed. Pooled mean values were estimated for VO2max and HbA1c and weighted Pearson correlation and meta-regression were performed to assess the association between these parameters. We included 187 studies with a total of 3278 individuals with T1DM. The pooled mean HbA1c value was 8.1% (95%CI; 7.9−8.3%), and relative VO2max was 38.5 mL/min/kg (37.3−39.6). The pooled mean VO2max was significantly lower (36.9 vs. 40.7, p = 0.001) in studies reporting a mean HbA1c > 7.5% compared to studies with a mean HbA1c ≤ 7.5%. Weighted Pearson correlation coefficient was r = −0.19 (p < 0.001) between VO2max and HbA1c. Meta-regression adjusted for age and sex showed a significant decrease of −0.94 mL/min/kg in VO2max per HbA1c increase of 1% (p = 0.024). In conclusion, we were able to determine a statistically significant correlation between HbA1c and VO2max in individuals with T1DM. However, as the correlation was only weak, the association of HbA1c and VO2max might not be of clinical relevance in individuals with T1DM.

Maximal Oxygen Uptake, VO2 Max, Testing Effect on Blood Glucose Level in Adolescents with Type 1 Diabetes Mellitus

Assessing maximal oxygen uptake (VO2 max) is generally considered safe when performed properly for most adolescents; however, for adolescents with type 1 diabetes mellitus (T1DM), monitoring glucose levels before and after exercise is critical to maintaining euglycemic ranges. Limited guidance exists for glucose level recommendations for the pediatric population; therefore, the purpose of this retrospective clinical chart review study was to determine the effects of VO2 max testing on blood glucose levels for adolescents with T1DM. A total of 22 adolescents (mean age = 15.6 ± 1.8 years; male = 13, 59.1%) with a diagnosis of T1DM participated in a Bruce protocol for VO2 max from January 2019 through February 2020. A statistically significant reduction in glucose levels between pretest (<30 min, mean = 191.1 mg/dL ± 61.2) and post-test VO2 max (<5 min, mean = 166.7 mg/dL ± 57.9); t(21) = 2.3, p < 0.05) was detected. The results from this current study can help guide health and fitness professionals in formulating glycemic management strategies in preparatory activities prior to exercise testing and during exercise testing.

The Potential of Current Noninvasive Wearable Technology for the Monitoring of Physiological Signals in the Management of Type 1 Diabetes: Literature Survey

Background

Monitoring glucose and other parameters in persons with type 1 diabetes (T1D) can enhance acute glycemic management and the diagnosis of long-term complications of the disease. For most persons living with T1D, the determination of insulin delivery is based on a single measured parameter—glucose. To date, wearable sensors exist that enable the seamless, noninvasive, and low-cost monitoring of multiple physiological parameters.

Objective

The objective of this literature survey is to explore whether some of the physiological parameters that can be monitored with noninvasive, wearable sensors may be used to enhance T1D management.

Methods

A list of physiological parameters, which can be monitored by using wearable sensors available in 2020, was compiled by a thorough review of the devices available in the market. A literature survey was performed using search terms related to T1D combined with the identified physiological parameters. The selected publications were restricted to human studies, which had at least their abstracts available. The PubMed and Scopus databases were interrogated. In total, 77 articles were retained and analyzed based on the following two axes: the reported relations between these parameters and T1D, which were found by comparing persons with T1D and healthy control participants, and the potential areas for T1D enhancement via the further analysis of the found relationships in studies working within T1D cohorts.

Results

On the basis of our search methodology, 626 articles were returned, and after applying our exclusion criteria, 77 (12.3%) articles were retained. Physiological parameters with potential for monitoring by using noninvasive wearable devices in persons with T1D included those related to cardiac autonomic function, cardiorespiratory control balance and fitness, sudomotor function, and skin temperature. Cardiac autonomic function measures, particularly the indices of heart rate and heart rate variability, have been shown to be valuable in diagnosing and monitoring cardiac autonomic neuropathy and, potentially, predicting and detecting hypoglycemia. All identified physiological parameters were shown to be associated with some aspects of diabetes complications, such as retinopathy, neuropathy, and nephropathy, as well as macrovascular disease, with capacity for early risk prediction. However, although they can be monitored by available wearable sensors, most studies have yet to adopt them, as opposed to using more conventional devices.

Conclusions

Wearable sensors have the potential to augment T1D sensing with additional, informative biomarkers, which can be monitored noninvasively, seamlessly, and continuously. However, significant challenges associated with measurement accuracy, removal of noise and motion artifacts, and smart decision-making exist. Consequently, research should focus on harvesting the information hidden in the complex data generated by wearable sensors and on developing models and smart decision strategies to optimize the incorporation of these novel inputs into T1D interventions.

Erectile dysfunction and diabetes: A melting pot of circumstances and treatments

Diabetes mellitus (DM), a chronic metabolic disease characterised by elevated levels of blood glucose, is among the most common chronic diseases. The incidence and prevalence of DM have been increasing over the years. The complications of DM represent a serious health problem. The long-term complications include macroangiopathy, microangiopathy and neuropathy as well as sexual dysfunction (SD) in both men and women. Erectile dysfunction (ED) has been considered the most important SD in men with DM. The prevalence of ED is approximately 3.5-fold higher in men with DM than in those without DM. Common risk factors for the development of DM and its complications include sedentary lifestyle, overweight/obesity and increased caloric consumption. Although lifestyle changes may help improve sexual function, specific treatments are often needed. This study aims to review the definition and prevalence of ED in DM, the impact of DM complications and DM treatment on ED and, finally, the current and emerging therapies for ED in patients with DM.

Blood Glucose Responses during Cardiopulmonary Incremental Exercise Testing in Type 1 Diabetes: A Pooled Analysis

PURPOSE

This study aimed to determine the glycemic responses to cardiopulmonary exercise testing (CPET) in individuals with type 1 diabetes (T1D) and to explore the influence of starting blood glucose (BG) concentrations on subsequent CPET outcomes.

METHODS

This study was a retrospective, secondary analysis of pooled data from three randomized crossover trials using identical CPET protocols. During cycling, cardiopulmonary variables were measured continuously, with BG and lactate values obtained minutely via capillary earlobe sampling. Anaerobic threshold was determined using ventilatory parameters. Participants were split into (i) euglycemic ([Eu] >3.9 to ≤10.0 mmol·L-1, n = 26) and (ii) hyperglycemic ([Hyper] >10.0 mmol·L-1, n = 10) groups based on preexercise BG concentrations. Data were assessed via general linear modeling techniques and regression analyses. P values of ≤0.05 were accepted as significant.

RESULTS

Data from 36 individuals with T1D (HbA1c, 7.3% ± 1.1% [56.0 ± 11.5 mmol·mol-1]) were included. BG remained equivalent to preexercise concentrations throughout CPET, with an overall change in BG of -0.32 ± 1.43 mmol·L-1. Hyper had higher HR at peak (+10 ± 2 bpm, P = 0.04) and during recovery (+9 ± 2 bpm, P = 0.038) as well as lower O2 pulse during the cool down period (-1.6 ± 0.04 mL per beat, P = 0.021). BG responses were comparable between glycemic groups. Higher preexercise BG led to greater lactate formation during exercise. HbA1c was inversely related to time to exhaustion (r = -0.388, P = 0.04) as well as peak power output (r = -0.355, P = 0.006) and O2 pulse (r = -0.308, P = 0.015).

CONCLUSIONS

This study demonstrated 1) stable BG responses to CPET in patients with T1D; 2) although preexercise hyperglycemia did not influence subsequent glycemic dynamics, it did potentiate alterations in various cardiac and metabolic responses to CPET; and 3) HbA1c was a significant factor in the determination of peak performance outcomes during CPET.

Differences in Physiological Responses to Cardiopulmonary Exercise Testing in Adults With and Without Type 1 Diabetes: A Pooled Analysis

OBJECTIVE

To investigate physiological responses to cardiopulmonary exercise (CPX) testing in adults with type 1 diabetes compared with age-, sex-, and BMI-matched control participants without type 1 diabetes.

RESEARCH DESIGN AND METHODS

We compared results from CPX tests on a cycle ergometer in individuals with type 1 diabetes and control participants without type 1 diabetes. Parameters were peak and threshold variables of VO₂, heart rate, and power output. Differences between groups were investigated through restricted maximum likelihood modeling and post hoc tests. Differences between groups were explained by stepwise linear regressions (P < 0.05).

RESULTS

Among 303 individuals with type 1 diabetes (age 33 [interquartile range 22; 43] years, 93 females, BMI 23.6 [22; 26] kg/m², HbA_1c 6.9% [6.2; 7.7%] [52 (44; 61) mmol/mol]), VO_2peak (32.55 [26.49; 38.72] vs. 42.67 ± 10.44 mL/kg/min), peak heart rate (179 [170; 187] vs. 184 [175; 191] beats/min), and peak power (216 [171; 253] vs. 245 [200; 300] W) were lower compared with 308 control participants without type 1 diabetes (all P < 0.001). Individuals with type 1 diabetes displayed an impaired degree and direction of the heart rate-to-performance curve compared with control participants without type 1 diabetes (0.07 [-0.75; 1.09] vs. 0.66 [-0.28; 1.45]; P < 0.001). None of the exercise physiological responses were associated with HbA_1c in individuals with type 1 diabetes.

CONCLUSIONS

Individuals with type 1 diabetes show altered responses to CPX testing, which cannot be explained by HbA_1c. Intriguingly, the participants in our cohort were people with recent-onset type 1 diabetes; heart rate dynamics were altered during CPX testing.

Continuous walking and time- and intensity-matched interval walking: Cardiometabolic demand and post-exercise enjoyment in insufficiently active, healthy adults

We compared cardiometabolic demand and post-exercise enjoyment between continuous walking (CW) and time- and intensity-matched interval walking (IW) in insufficiently active adults. Sixteen individuals (13 females and three males, age 25.3 ± 11.1 years) completed one CW and one IW session lasting 30 min in a randomised-counterbalanced design. For CW, participants walked at a mean intensity of 65-70% predicted maximum heart rate (HR_max). For IW, participants alternated between 3 min at 80% HR_max and 2 min at 50% HR_max. Expired gas was measured throughout each protocol. Participants rated post-exercise enjoyment following each protocol. Mean HR and V˙O₂ showed small positive differences in IW vs. CW (2, 95%CL 0, 4 beat.min^-1; d = 0.23, 95%CL 0.06, 0.41 and 1.4, 95%CL 1.2 ml.kg^-1.min^-1, d = 0.36, 95%CL 0.05, 0.65, respectively). There was a medium positive difference in overall kcal expenditure in IW vs. CW (25, 95%CL 7 kcal, d = 0.58, 95%CL 0.33, 0.82). Post-exercise enjoyment was moderately greater following IW vs. CW (9.1, 95%CL 1.4, 16.8 AU, d = 0.62, 95%CL 0.06, 0.90), with 75% of participants reporting IW as more enjoyable. Interval walking elicits meaningfully greater energy expenditure and is more enjoyable than CW in insufficiently active, healthy adults.

Acute glycemic responses along 10-week high-intensity training protocols in type 1 diabetes patients

Glycemic fluctuations were compared throughout 10-week high-intensity training protocols in T1DM patients. Differences were compared using the rate of change in glycaemia during exercise (RoC_E). HIIT sessions led to lower RoC_E in most weeks than other training protocols. The occurrence of level 1 hypoglycemia along sessions were similar among interventions.

The Effects of Chronic Aerobic Exercise on Cardiovascular Risk Factors in Persons with Diabetes Mellitus

PURPOSE OF REVIEW

Aerobic exercise training is a component of diabetes mellitus (DM) care guidelines due to its favorable effects on glycemic control and cardiovascular disease (CVD) risk factors. The purpose of this review is to outline the recent evidence regarding the clinical effects of chronic aerobic exercise on CVD risk factors in persons with DM and to compare the effects of varying intensities and types of exercise.

RECENT FINDINGS

Among individuals with DM, all types of aerobic exercise training can impact positively on some traditional and non-traditional risk factors for CVD. Training programs with a higher volume or intensity induce greater improvements in vascular function, cardiorespiratory fitness (CRF), and lipid profiles. The beneficial outcomes of aerobic training include improvements in glycemic control, endothelial function, oxidative stress, dyslipidemia, myocardial function, adiposity, and CRF. Findings regarding markers of inflammation are discrepant and further research should focus on the role of exercise to impact upon the chronic inflammation associated with DM.

Poor glycaemic control is associated with reduced exercise performance and oxygen economy during cardio-pulmonary exercise testing in people with type 1 diabetes

BACKGROUND

To explore the impact of glycaemic control (HbA_1c) on functional capacity during cardio-pulmonary exercise testing in people with type 1 diabetes.

METHODS

Sixty-four individuals with type 1 diabetes (age: 34 ± 8 years; 13 females, HbA_1c: 7.8 ± 1% (62 ± 13 mmol/mol), duration of diabetes: 17 ± 9 years) performed a cardio-pulmonary cycle ergometer exercise test until volitional exhaustion. Stepwise linear regression was used to explore relationships between HbA_1c and cardio-respiratory data with p ≤ 0.05. Furthermore, participants were divided into quartiles based on HbA_1c levels and cardio-respiratory data were analysed by one-way ANOVA. Multiple regression analysis was performed to explore the relationships between changes in time to exhaustion and cardio-respiratory data. Data were adjusted for confounder.

RESULTS

HbA_1c was related to time to exhaustion and oxygen consumption at the power output elicited at the sub-maximal threshold of the heart rate turn point (r = 0.47, R² = 0.22, p = 0.03). Significant differences were found at time to exhaustion between QI vs. QIV and at oxygen consumption at the power output elicited at the heart rate turn point between QI vs. QII and QI vs. QIV (p < 0.05). Changes in oxygen uptake, power output and in oxygen consumption at the power output elicited at the heart rate turn point and at maximum power output explained 55% of the variance in time to exhaustion (r = 0.74, R² = 0.55, p < 0.01).

CONCLUSIONS

Poor glycaemic control is related to less economical use of oxygen at sub-maximal work rates and an earlier time to exhaustion during cardio-pulmonary exercise testing. However, exercise training could have the same potential to counteract the influence of poor glycaemic control on functional capacity. Trial registration NCT01704417. Date of registration: October 11, 2012.