Determinants of Exercise Capacity in Patients With Type 2 Diabetes

Abstract

OBJECTIVE -Type 2 diabetes is associated with reduced exercise capacity, but the cause of this association is unclear. We sought the associations of impaired exercise capacity in type 2 diabetes. RESEARCH DESIGN AND METHODS -Subclinical left ventricular (LV) dysfunctionwas sought from myocardial strain rate and the basal segmental diastolic velocity (Em) of each wall in 170 patients with type 2 diabetes (aged 56 Ϯ 10 years, 91 men), good quality echocardiographic images, and negative exercise echocardiograms. The same measurements were made in 56 control subjects (aged 53 Ϯ 10 years, 29 men). Exercise capacity was calculated in metabolic equivalents, and heart rate recovery (HRR) was measured as the heart rate difference between peak and 1 min after exercise. In subjects with type 2 diabetes, exercise capacity was correlated with clinical, therapeutic, biochemical, and echocardiographic variables, and significant independent associations were sought using a multiple linear regression model. RESULTS -Exercise capacity, strain rate, Em, and HRR were significantly reduced in type 2 diabetes. Exercise capacity was associated with age (r ϭ Ϫ0.37, P Ͻ 0.001), male sex (r ϭ 0.26, P ϭ 0.001), BMI (r ϭ Ϫ0.19, P ϭ 0.012), HbA 1c (A1C; r ϭ Ϫ0.22, P ϭ 0.009), Em (r ϭ 0.43, P Ͻ 0.001), HRR (r ϭ 0.42, P Ͻ 0.001), diabetes duration (r ϭ Ϫ0.18, P ϭ 0.021), and hypertension history (r ϭ Ϫ0.28, P Ͻ 0.001). Age (P Ͻ 0.001), male sex (P ϭ 0.007), BMI (P ϭ 0.001), Em (P ϭ 0.032), HRR (P ϭ 0.013), and A1C (P ϭ 0.0007) were independent predictors of exercise capacity.CONCLUSIONS -Reduced exercise capacity in patients with type 2 diabetes is associated with diabetes control, subclinical LV dysfunction, and impaired HRR. Diabetes Care 28:1643-1648, 2005C linical and observational studies have shown that exercise capacity is a strong predictor of cardiovascular and overall mortality (1). Patients with type 2 diabetes often complain of fatigue and reduced exercise capacity. Although these symptoms may be related to other disease conditions, such as hypertensive left ventricular (LV) hypertrophy or coronary artery disease, the presence of diabetes may independently contribute to the impaired exercise capacity (2).The causes of reduced exercise capacity in type 2 diabetes are unknown. Overt LV diastolic dysfunction, evidenced by abnormal transmitral flow, has been associated with impaired functional capacity in uncomplicated well-controlled type 2 diabetes (2). However, primary myocardial disease may be present in many patients with type 2 diabetes, without overt systolic or diastolic dysfunction, independent of LV hypertrophy and coronary artery disease (3). Cardiac autonomic dysfunction may play an important role in the development of diabetic heart disease (3). Reduced heart rate recovery (HRR) immediately after exercise is an important indicator of cardiac autonomic dysfunction and contributes to cardiovascular morbidity and mortality in other diseases (4,5). In this study, we sought the extent to which diabetes control, impaired HRR, a...

Benefit of Combined Cardiac Rehabilitation on Exercise Capacity and Cardiovascular Parameters in Patients with Type 2 Diabetes

“…Before starting the training program, the values of exercise capacity W peak /kg, V O 2peak /kg and the corresponding RPP peak were significantly lower in DM patients than in NDM group, although the values of W peak and V O 2peak did not differ significantly. These results correspond to previously published studies, demonstrating that the DM2 is associated with cardiovascular dysfunction including reduced exercise capacity and physical fitness, which are strong predictors of cardiovascular mortality (Milani and Lavie 1996;ACSM 2000;ADA 2001;Banzer et al 2004;Fang et al 2004Fang et al , 2005. It has been repeatedly reported that hyperglycemia is associated with increased stiffness of large vessels including aorta.…”

Impaired stroke volume and aerobic capacity in female adolescents with type 1 and type 2 diabetes mellitus

“…An alternative explanation is that autonomic dysfunction, which appears in diabetic adults [8], occurs in type 2 diabetic adolescents. Autonomic neuropathy has been described early after the diagnosis of type 2 diabetes [4] and reduced maximal heart rate has been reported in type 2 diabetic adults [9]. Of particular interest, type 2 diabetic female adolescents may have lower heart rate variability than type 1 diabetic adolescents [4].…”

The Diabetic Lung - A New Target Organ?

“…Regarding the exercise capacity in type 2 diabetic patients, the same detrimental effects of diabetes on VO2 kinetics, VO2 peak, and ventilatory threshold have been described [86][87][88][89]. However, the results of studies evaluating whether glycemic control could affect exercise tolerance in patients with type 2 diabetes are conflicting [86,87,[90][91][92].…”