Effect of low-volume combined aerobic and resistance high-intensity interval training on vascular health in people with type 2 diabetes: a randomised controlled trial.

PURPOSE: We compared the effects of low-volume combined aerobic and resistance high-intensity interval training (C-HIIT), combined moderate-intensity continuous training (C-MICT) and waitlist control (CON) on vascular health after 8-weeks of supervised training, and an additional 10-months of self-directed training, in adults with type 2 diabetes (T2D). METHODS: Sixty-nine low active adults with T2D were randomised to 8-weeks of supervised C-HIIT (3 times/week, 78-min/week), C-MICT (current exercise guidelines, 4 times/week, 210-min/week) or CON. CON underwent usual care for 8-weeks before being re-randomised to C-HIIT or C-MICT. This was followed by 10-months of self-directed training for participants in C-HIIT and C-MICT. Vascular outcomes were evaluated at baseline, 8-weeks, and 12-months. RESULTS: After 8-weeks, supervised C-HIIT significantly improved relative flow-mediated dilation (FMD) compared with CON (mean difference [MD] 0.8% [0.1, 1.4], p = 0.025). Although not significantly different from CON, the magnitude of change in relative FMD following 8-weeks of supervised C-MICT was similar (MD 0.8% [-0.1, 1.7], p = 0.080). There were no differences in haemodynamic indices, carotid-femoral pulse wave velocity (cfPWV), or aortic reservoir pressure between groups at 8-weeks. After 12-months, there was a significant reduction in haemodynamic indices (time effect, p < 0.05) for both C-HIIT and C-MICT, with no between-group difference. The reduction in cfPWV over 12-months was significantly greater in C-MICT than C-HIIT (group × time effect, p = 0.018). There was no difference in FMD over time or between groups at 12-months. CONCLUSIONS: Short-term supervised C-HIIT and C-MICT both increased brachial artery FMD compared with CON. Long-term C-HIIT and C-MICT were beneficial for improving haemodynamic indices, but not brachial artery FMD. C-MICT was superior to C-HIIT for improving cfPWV at 12-months. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry Identifier ACTRN12615000475549.

Comparing the Efficacy of Supervised and Unsupervised Exercise Training on Glycaemic Control in Type 2 Diabetes: A Systematic Review.

BACKGROUND: Exercise training is vital for glycaemic control in patients with type 2 diabetes mellitus (T2D). While the positive effects of supervised exercise training are well established, unsupervised training may offer an alternative and more sustainable means of realising the benefits of exercise away from a resource-heavy supervised setting. OBJECTIVE: To evaluate the available literature and compare the efficacy of supervised and unsupervised exercise training programs on glycemic control in patients with T2D. METHODS: CINAHL, MEDLINE, PubMed, and EMBASE, searched from inception to 20 July 2018. Only studies that included both supervised and unsupervised training were included. RESULTS: Four studies, involving 115 participants, were included. One compared supervised with unsupervised exercise training and three investigated the efficacy of unsupervised training following supervised training. While supervised training is effective for improving glycaemic control in patients with T2D, unsupervised training may not maintain these changes. Included studies lacked detail relating to the supervised and unsupervised training programs. CONCLUSIONS: Given that exercise is a critical component for maintenance of glycaemic control in patients with T2D, and because unsupervised training has been shown to be effective in improving clinical outcomes in other disease populations, further research is warranted to compare supervised and unsupervised exercise training in patients with T2D. It is important that future studies report standardised and detailed descriptions of key elements that form the basis of supervised and unsupervised exercise training groups.

Subclinical LV dysfunction and 10-year outcomes in type 2 diabetes mellitus.

OBJECTIVE: New imaging techniques have permitted the detection of subclinical LV dysfunction (LVD) in up to half of patients with type 2 diabetes mellitus (DM) with a normal EF. However, the connection between early LVD and prognosis is unclear. This study aimed to define the long-term outcome of LVD associated with type 2 DM. METHODS: In this prospective cohort study, 230 asymptomatic patients with type 2 DM underwent measurement of global longitudinal 2D strain (GLS) for detection of LVD and were followed for up to 10 years. All subjects had normal EF (≥50%) and no evidence of coronary artery disease at recruitment. Outcome data were obtained through centralised state-wide death and hospital admission registries. The primary endpoint was all-cause mortality and hospitalisation. RESULTS: On study entry, almost half (45%) of the cohort had evidence of LVD as detected by GLS. Over a median follow-up of 7.4±2.6 years (range 0.6-9.7 years), 68 patients (30%) met the primary endpoint (LVD: 37%; normal LV function: 24%). GLS was independently associated with the primary endpoint (HR=1.10; p=0.04), as was systolic blood pressure (HR=1.02; p<0.001) and levels of glycosylated haemoglobin (HR=1.28; p=0.011). Patients with LVD had significantly worse outcome than those without (χ(2)=4.73; p=0.030). CONCLUSIONS: Subclinical LVD is common in asymptomatic patients with type 2 DM, is readily detectable by GLS imaging and is independently associated with adverse outcome. TRIAL REGISTRATION NUMBER: Australian and New Zealand Clinical Trials Registry (ACTRN12612001178831).

Exercise prescription for patients with type 2 diabetes and pre-diabetes: a position statement from Exercise and Sport Science Australia.

Type 2 diabetes mellitus (T2DM) and pre-diabetic conditions such as impaired fasting glucose (IFG) and/or impaired glucose tolerance (IGT) are rapidly increasing in prevalence. There is compelling evidence that T2DM is more likely to develop in individuals who are insufficiently active. Exercise training, often in combination with other lifestyle strategies, has beneficial effects on preventing the onset of T2DM and improving glycaemic control in those with pre-diabetes. In addition, exercise training improves cardiovascular risk profile, body composition and cardiorespiratory fitness, all strongly related to better health outcomes. Based on the evidence, it is recommended that patients with T2DM or pre-diabetes accumulate a minimum of 210 min per week of moderate-intensity exercise or 125 min per week of vigorous intensity exercise with no more than two consecutive days without training. Vigorous intensity exercise is more time efficient and may also result in greater benefits in appropriate individuals with consideration of complications and contraindications. It is further recommended that two or more resistance training sessions per week (2-4 sets of 8-10 repetitions) should be included in the total 210 or 125 min of moderate or vigorous exercise, respectively. It is also recommended that, due to the high prevalence and incidence of comorbid conditions in patients with T2DM, exercise training programs should be written and delivered by individuals with appropriate qualifications and experience to recognise and accommodate comorbidities and complications.

Application of an exercise intervention on the evolution of diastolic dysfunction in patients with diabetes mellitus: efficacy and effectiveness.

BACKGROUND: Diastolic dysfunction (DD) is associated with adverse cardiovascular outcomes. We studied the impact of an exercise-based lifestyle intervention on the evolution of DD in patients with type 2 diabetes mellitus (T2DM) and prospectively investigated the clinical correlates of DD progression. METHODS AND RESULTS: A total of 223 outpatients with T2DM were randomized to supervised exercise-based lifestyle intervention (initial gym-based program and lifestyle and diet advice followed by telephone-guided supervision) or usual care. Patients underwent echocardiographic assessment of diastolic function and metabolic and clinical evaluation at baseline and 3 years. Changes in prevalence and evolution of DD were assessed and correlations sought with clinical and metabolic variables. DD was present in 50% of patients at baseline and 54% at 3 years, with no difference between the usual care and intervention groups (60% versus 48%, P=0.10). Abnormal DD at the final visit was independently associated with older age and a decrease in peak oxygen consumption over time (P<0.05). There was no impact on glycemic control or exercise capacity. In a subanalysis restricted to patients who finished the full 3-year follow-up, control subjects were independently associated with DD at 3 years (ß=0.90; odds ratio, 2.46; P=0.034), with the only other independent correlate being older age (ß=0.05; odds ratio, 1.06; P=0.019). CONCLUSIONS: Despite being efficacious in the subgroup who completed 3 years of exercise-based lifestyle intervention, randomization to this program was not effective in reducing progression of subclinical DD in patients with T2DM, which may reflect the recognized difficulty of adherence to prolonged exercise intervention. CLINICAL TRIAL REGISTRATION: URL: http://www.anzctr.org.au. Unique identifier: ACTRN12607000060448.

Lifestyle change diminishes a hypertensive response to exercise in type 2 diabetes.

PURPOSE: A hypertensive response to exercise (HRE) is common in patients with type 2 diabetes and is associated with increased left ventricular (LV) mass and mortality. This study aimed to determine whether lifestyle modification would improve exercise blood pressure (BP) and reduce LV mass in patients with type 2 diabetes. METHODS: One hundred and eighty-five patients with type 2 diabetes were randomized to 1 yr of lifestyle intervention (n=97, mean ± SD age=54.7 ± 11.3 yr, 51% men) or usual care (control; n=88, age=53.8 ± 8.1 yr, 61% men). Brachial BP was measured at rest and during a graded maximal exercise test at baseline and 1 yr. Patients also underwent two-dimensional echocardiography to determine LV dimensions. A subgroup of 61 patients had resting and exercise central BP estimated from radial tonometry. An HRE was defined as a maximal exercise systolic BP of ≥210 mm Hg for men and ≥190 mm Hg for women. RESULTS: At study entry, there were 101 patients (55%) with an HRE (n=51 controls). Compared with controls, lifestyle intervention significantly reduced the propensity to develop an HRE in those participants who did not have HRE at baseline (29.8% vs 59.5%, P=0.006). However, absolute values of exercise and resting (brachial and central) BP and LV mass were not significantly changed (all P values >0.05). There were significant (all P values <0.05) improvements in V˙O2max, body mass index, plasma glucose, insulin resistance, and HDL cholesterol after lifestyle intervention compared with control. CONCLUSIONS: Lifestyle intervention significantly attenuates the development of an HRE but does not reduce cardiac size after 1 yr in patients with type 2 diabetes.

Acute response of blood glucose to short-term exercise training in patients with type 2 diabetes.

It is unclear whether the glucose lowering effects of an exercise session are augmented by training. Therefore, we sought to assess the effects of a four-week exercise training program on the acute response of blood glucose to a single exercise session in patients with T2DM. A Quasi experimental design was used. Thirty-four patients with T2DM (18 males) completed a four-week exercise regime consisting of two 1-h supervised sessions and one 30 min unsupervised home session per week. The sessions contained cardiorespiratory and resistance exercises. Blood glucose was measured prior to and after each training session. Resting heart rate (HR), blood pressure (BP), body composition, lipid profile and cardiorespiratory fitness (VO2max) were determined before and after the four week training program. Decreases in blood glucose (pre to post exercise session) over the four weeks were (mean±SD); week 1: 13.3±18.6%, week 2: 19.7±18.5%, week 3: 18.1±20.8%, week 4: 22.8±17.9%. General linear modelling with repeated measures ANCOVA showed that there was a significant (p<0.01) time effect over this period. Additionally, there were small, but significant decreases in resting heart rate (-6.6±10.3 bpm, p=0.001), systolic blood pressure (-5.6±14.9 mmHg, p=0.043) and fat mass (-1.6±3.2%, p=0.024) and an increase in VO(2max) (1.6±3.7 ml/kg/min, p=0.025) over the four weeks. Four weeks of exercise training augments the exercise-induced decrease in blood glucose that occurs in a single exercise session.

Determinants of changes in blood glucose response to short-term exercise training in patients with Type 2 diabetes.

The aim of the present study was to determine the effects of a 4-week exercise training intervention on blood glucose, insulin sensitivity, BMI (body mass index) and cardiorespiratory fitness in patients with Type 2 diabetes, and to identify and establish criteria for patients who are more likely to improve their blood glucose from short-term exercise training. A randomized, controlled trial of exercise training, comprising two supervised and one non-supervised sessions of individualized cardiorespiratory and resistance exercise per week, was performed in 132 healthy patients with Type 2 diabetes (exercise training group, n=68), with the aim of accumulating a minimum of 150 min of moderate-intensity exercise for 4 weeks. BMI, waist circumference, blood pressure, blood lipid profile, blood glucose, insulin, insulin sensitivity [calculated by HOMA(IR) (homoeostasis model assessment of insulin resistance) and QUICKI (quantitative insulin check index)], beta-cell function (calculated by HOMA(beta-Cell)), HbA(1c) (glycated haemoglobin) and VO(2max) (maximal oxygen consumption) were measured at baseline and at 4 weeks. The exercise training group had significant improvements in VO(2max), BMI and triacylglycerols (triglycerides). There were no significant changes in blood glucose, HOMA(IR), QUICKI or HOMA(beta-Cell). Decreases in blood glucose were significantly predicted by baseline blood glucose and HbA(1c), with these variables accounting for 15.9% of the change in blood glucose (P<0.001). ROC (receiver operator characteristic) curve analysis revealed that patients with a blood glucose >8.85 mmol/l (sensitivity=73%, specificity=78%) and HbA(1c) >7.15% (sensitivity=79%, specificity=60%) were more likely to achieve a clinically significant decrease in blood glucose. In conclusion, in apparently healthy patients with Type 2 diabetes, a 4-week exercise intervention improved cardiorespiratory fitness, BMI and triacylglycerols. Elevated blood glucose and HbA(1c) predicted improvements in blood glucose.